The Address Resolution Protocol (ARP) resolves IP addresses to MAC addresses to allow communication between hosts on a local area network (LAN). ARP maintains a cache that maps IP addresses to MAC addresses. Static and dynamic entries are stored in the ARP cache, with dynamic entries expiring after a timeout period. Proxy ARP and other protocols like Reverse ARP and Serial Line ARP provide additional ARP functionality in certain network configurations.
ARP resolves IP addresses to MAC addresses for local network delivery. It uses broadcast datagrams to request MAC addresses and unicasts to reply. Proxy ARP allows routers to answer for hosts on remote networks during subnet transition. RARP and Inverse ARP work in reverse to resolve MAC addresses to IP addresses.
Address resolution protocol and internet control message protocolasimnawaz54
ICMP provides error reporting and feedback messages for IP. It uses IP datagrams to transport control messages between hosts and routers. ICMP messages include echo requests/replies used by ping, time exceeded and destination unreachable errors, redirects, and path MTU discovery fragments needed messages. ARP resolves IP addresses to hardware addresses locally through broadcast requests and unicast replies to populate caches. Proxy ARP allows routers to answer for hosts on remote networks to allow communication before subnet migration.
ARP enables hosts on a network to dynamically map IP addresses to physical hardware addresses. Each host maintains an ARP cache containing IP to physical address mappings. When a host needs to send data to another host, it first checks its ARP cache for the mapping. If no mapping exists, the host broadcasts an ARP request containing the target IP address. The host with that IP address responds with its physical address, which the requesting host adds to its ARP cache. This process allows hosts to dynamically learn each other's physical addresses as needed for packet transmission.
ARP is a protocol that maps IP addresses to MAC addresses. It works by broadcasting an ARP request packet to all devices on the local network segment. The device with the matching IP address responds with its MAC address, allowing the requesting device to send packets directly to the destination MAC address on the local network.
The document discusses address resolution protocol (ARP) which maps logical IP addresses to physical MAC addresses on a local area network. It explains that ARP broadcasts a request to find the MAC address associated with a given IP address, and the device with that IP address responds with its MAC. This dynamic address mapping is stored in an ARP cache for future use. It also describes how different network protocols may use ARP or similar methods to perform address mapping between logical and physical addresses.
ARP and RARP protocols are used to map IP addresses to MAC addresses on local area networks. ARP requests are broadcast to the network to resolve IP to MAC addresses, and ARP replies provide the requested mapping. Hosts cache ARP entries to avoid frequent address resolution, with entries expiring after 20 minutes. Proxy ARP allows a router to respond to ARP requests on behalf of hosts on different connected networks.
ARP (Address Resolution Protocol) maps logical IP addresses to physical MAC addresses. It works by broadcasting an ARP request packet containing the logical IP address, and the physical host with that IP will respond with its MAC address in an ARP reply packet. ARP packets are encapsulated within Ethernet frames to be transmitted at the data link layer, and ARP is used to resolve addresses both for hosts on the same local network and for traffic destined for a default router on another network.
This document discusses address resolution protocol (ARP) which is used to map IP addresses to MAC addresses on local area networks (LANs). It explains that ARP resolves destination IP addresses to MAC addresses in order to direct transmissions to specific devices on the LAN. It provides examples of how ARP is used to resolve addresses across multiple networks. It describes the basic ARP message format and exchange process used for address resolution.
ARP resolves IP addresses to MAC addresses for local network delivery. It uses broadcast datagrams to request MAC addresses and unicasts to reply. Proxy ARP allows routers to answer for hosts on remote networks during subnet transition. RARP and Inverse ARP work in reverse to resolve MAC addresses to IP addresses.
Address resolution protocol and internet control message protocolasimnawaz54
ICMP provides error reporting and feedback messages for IP. It uses IP datagrams to transport control messages between hosts and routers. ICMP messages include echo requests/replies used by ping, time exceeded and destination unreachable errors, redirects, and path MTU discovery fragments needed messages. ARP resolves IP addresses to hardware addresses locally through broadcast requests and unicast replies to populate caches. Proxy ARP allows routers to answer for hosts on remote networks to allow communication before subnet migration.
ARP enables hosts on a network to dynamically map IP addresses to physical hardware addresses. Each host maintains an ARP cache containing IP to physical address mappings. When a host needs to send data to another host, it first checks its ARP cache for the mapping. If no mapping exists, the host broadcasts an ARP request containing the target IP address. The host with that IP address responds with its physical address, which the requesting host adds to its ARP cache. This process allows hosts to dynamically learn each other's physical addresses as needed for packet transmission.
ARP is a protocol that maps IP addresses to MAC addresses. It works by broadcasting an ARP request packet to all devices on the local network segment. The device with the matching IP address responds with its MAC address, allowing the requesting device to send packets directly to the destination MAC address on the local network.
The document discusses address resolution protocol (ARP) which maps logical IP addresses to physical MAC addresses on a local area network. It explains that ARP broadcasts a request to find the MAC address associated with a given IP address, and the device with that IP address responds with its MAC. This dynamic address mapping is stored in an ARP cache for future use. It also describes how different network protocols may use ARP or similar methods to perform address mapping between logical and physical addresses.
ARP and RARP protocols are used to map IP addresses to MAC addresses on local area networks. ARP requests are broadcast to the network to resolve IP to MAC addresses, and ARP replies provide the requested mapping. Hosts cache ARP entries to avoid frequent address resolution, with entries expiring after 20 minutes. Proxy ARP allows a router to respond to ARP requests on behalf of hosts on different connected networks.
ARP (Address Resolution Protocol) maps logical IP addresses to physical MAC addresses. It works by broadcasting an ARP request packet containing the logical IP address, and the physical host with that IP will respond with its MAC address in an ARP reply packet. ARP packets are encapsulated within Ethernet frames to be transmitted at the data link layer, and ARP is used to resolve addresses both for hosts on the same local network and for traffic destined for a default router on another network.
This document discusses address resolution protocol (ARP) which is used to map IP addresses to MAC addresses on local area networks (LANs). It explains that ARP resolves destination IP addresses to MAC addresses in order to direct transmissions to specific devices on the LAN. It provides examples of how ARP is used to resolve addresses across multiple networks. It describes the basic ARP message format and exchange process used for address resolution.
Gourav Salla presented on Address Resolution Protocol (ARP). ARP is used to map IP addresses to MAC addresses so devices can communicate on a local network. It works by broadcasting an ARP request packet containing the target IP address. The device with that IP address responds with its MAC address. This address resolution allows packets for that destination to be sent directly using layer 2 addressing. ARP caches entries to avoid repeating the lookup for frequent communication between devices on the same subnet.
The document discusses Address Resolution Protocol (ARP) and Reverse Address Resolution Protocol (RARP). It provides examples of how ARP is used to map IP addresses to MAC addresses on local networks and how RARP is used for the opposite mapping. It also includes diagrams of ARP and RARP packets and operations. The examples show how ARP and RARP are used and how their data structures are updated as new address mappings are learned or cached entries time out.
This document discusses ARP and RARP protocols. ARP is used to map IP addresses to MAC addresses on local networks. It works by broadcasting ARP requests and unicasting replies. RARP is used in the opposite direction, to map a device's MAC address to its IP address. Examples are given of how an ARP cache works, including entries for pending, resolved, and free states. RARP has been replaced by BOOTP and DHCP for providing additional configuration info like subnet masks.
This document discusses several common computer network protocols: CIDR for routing IP addresses more efficiently; NAT for sharing public IP addresses among private networks; ICMP for error detection; ARP for mapping IP addresses to MAC addresses; RARP and BOOTP as predecessors to DHCP for dynamically assigning private IP addresses; and DHCP, the current standard dynamic host configuration protocol.
This document provides an overview of the Address Resolution Protocol (ARP). It defines ARP as a network layer protocol that maps IP addresses to MAC addresses, allowing communication within a local area network. Key points include:
- ARP resolves logical IP addresses to physical MAC addresses to allow communication on the data link layer.
- IP and MAC addresses are respectively logical and physical identifiers for devices on a network.
- The ARP packet format and work procedure of ARP caching are described.
- ARP requests are broadcast to find MAC addresses, and ARP responses provide the discovered addresses.
- A drawback of ARP is that it is vulnerable to spoofing and denial of service attacks.
This document discusses ARP and RARP protocols. ARP associates IP addresses with physical addresses to allow communication on a LAN. RARP performs the inverse, associating physical addresses with IP addresses. The document includes objectives, figures illustrating ARP and RARP operation and positioning in the TCP/IP stack, examples of ARP cache usage, and details on ARP and RARP packet formats and processing. It aims to explain the need, components, and interactions of the ARP and RARP protocols.
This document provides a summary of network protocols. It defines a network as a set of connected devices that can send and receive data. It explains that network protocols establish detailed rules for how computer systems exchange information. The document then overview Reverse Address Resolution Protocol (RARP) and several other key network protocols, including Internet Protocol (IP), Address Resolution Protocol (ARP), Internet Group Message Protocol (IGMP), and Internet Control Message Protocol (ICMP). For each protocol, it provides high-level descriptions of their functions and operations in 2 sentences or less.
ARP (Address Resolution Protocol) maps logical IP addresses to physical MAC addresses. When a host wants to send data to another host locally, it first broadcasts an ARP request containing the target IP address. The target host responds with its MAC address in an ARP reply, which the requesting host uses to update its ARP table and directly address future communications.
Overview of RARP, BOOTP, DHCP and PXE protocols for dynamic IP address assignment.
Dynamic IP address assignment to a host (or interface) is a common problem in TCP/IP based networks.
Manual and static assignment of IP addresses does not scale well and becomes a labor intensive task with a growing number of hosts.
An early approach for dynamic IP address assignment was RARP (Reverse ARP) which ran directly on the Ethernet protocol layer.
The many problems of RARP such as the inability to be routed between subnets were solved with BOOTP (Bootstrap Protocol).
BOOTP, however, ended to have its own set of limitations like lack of a lease time for IP addresses.
DHCP (Dynamic Host Configuration Protocol) was therefore defined as an extension to BOOTP.
DHCP is backward compatible with BOOTP thus allowing some degree of interoperability between the 2 protocols.
The state-of-the-art protocol for dynamic IP address assignment is, however, is DHCP.
DHCPv6 is an adaption of DHCP for IPv6 based networks.
This document discusses several internet protocols, including ARP and RARP. ARP is used to convert IP addresses to physical addresses like Ethernet addresses. It operates below the network layer to interface between OSI layers. A host broadcasts an ARP request to obtain another device's physical address. RARP is used to resolve an IP address from a given hardware address. It has been replaced by newer protocols but was used by clients to request IP addresses from a network.
ARP spoofing allows an attacker to intercept or modify communications between two hosts on a local network by falsifying ARP responses and changing a target's ARP cache entries. The attacker sends spoofed ARP replies associating the target's IP addresses with the attacker's MAC address, intercepting traffic intended for another host. This enables man-in-the-middle attacks where the attacker can sniff or modify intercepted traffic before forwarding it. Defenses include static ARP entries and port security on switches, but weaknesses remain, especially on networks using dynamic addressing protocols like DHCP.
Address Resolution Protocol (ARP) is used to map network layer addresses (IP addresses) to data link layer addresses (MAC addresses). This process is necessary because communication between devices on a local network uses MAC addresses, while routing and forwarding between networks uses IP addresses. ARP works by broadcasting a request packet containing the target IP address, and the device with that IP address responds with its MAC address. If the MAC address is unknown, ARP uses a broadcast query to determine the address dynamically, while direct mapping provides a way to statically determine addresses through a formula.
Overview of IP routing protocols, packet forwarding and proxy ARP.
The principle of IP routing proved to be very flexible and scalable in the growth of the Internet and TCP/IP based networks.
IP routing denotes protocols for exchanging IP address range reachability like RIP, BGP and OSPF.
In contrast to IP routing, IP packet forwarding collectively means all functions performed when an IP router receives a packet and forwards it over the output interface indicated by an IP route in the routing table.
When an IP router performs a route lookup, it calculates a route decision based on different properties like prefix (mask) length, route precedence and metrics.
Routing protocols for exchanging route information can be coarsely classified as distance vector and link state protocols. Distance vector protocols like RIP (Routing Information Protocol) exchange information about the path cost to specific targets (IP address ranges). Routers that talk distance vector protocols receive reachability information about all sub-networks indirectly from neighboring routers.
In contrast to distance vector protocols, link state protocols like OSPF disseminate information about the link state of each router link in a network to all routers in the network. Thus link state protocols tend to converge faster to topology changes since all routers have firsthand information of the topology of the network.
Proxy ARP may be a convenient solution when it comes to add additional subnets without having to add routes to routers and hosts. A proxy ARP enabled router would answer ARP requests on behalf of the targeted hosts mimicking a local network access to the requesting host.
This document presents a technique to identify the correct IP to MAC address mapping when an attacker is performing ARP spoofing. It discusses limitations of existing probe packet-based detection techniques when facing a strong attacker. The proposed technique generates broadcast ARP requests to identify the correct mapping, even if the attacker can modify the protocol stack. Experimental results show the technique can correctly identify the attacker in both weak and strong attacking environments with only a small increase in network traffic overhead.
This document presents on the Reverse Address Resolution Protocol (RARP). It defines RARP as a protocol used to find the logical address for a machine that knows only its physical address. It describes how RARP works to dynamically map physical addresses to logical addresses, as ARP maps logical to physical addresses. The document outlines the uses of RARP and its limitations that led to its replacement by other protocols like BOOTP and DHCP.
This document discusses BOOTP and DHCP protocols. It provides objectives that will be covered, including the types of information required by systems on boot-up and how BOOTP and DHCP operate. BOOTP provides IP addresses and other network configuration details, while DHCP provides static and dynamic address allocation manually or automatically. The document includes figures illustrating operations, packet formats, and state diagrams for both protocols.
The document discusses ARP and RARP protocols. It provides examples of how ARP is used to dynamically map IP addresses to physical addresses in order to send packets between hosts on a local network. ARP broadcasts a request packet to find a target host's physical address and caches the result. RARP is used to obtain an IP address from a known physical address. Figures show the ARP process, encapsulation, different usage cases, and an example ARP exchange between two hosts.
The document discusses the Internet Control Message Protocol (ICMP). ICMP provides error reporting, congestion reporting, and first-hop router redirection. It uses IP to carry its data end-to-end and is considered an integral part of IP. ICMP messages are encapsulated in IP datagrams and are used to report errors in IP datagrams, though some errors may still result in datagrams being dropped without a report. ICMP defines various message types including error messages like destination unreachable and informational messages like echo request and reply.
The document discusses Address Resolution Protocol (ARP) and gratuitous ARP. ARP is used to map IP addresses to MAC addresses on a local network. It maintains an ARP cache table mapping addresses. Gratuitous ARP occurs when a device sends an ARP request for its own IP address, broadcasting its IP-MAC mapping to update switches and detect duplicate IP addresses on the network. It helps ensure unique IP addresses and informs switches of end device locations. The document provides examples of gratuitous ARP detecting and resolving a duplicate IP address scenario.
The document provides an overview of TCP/IP (Transmission Control Protocol/Internet Protocol). It discusses the history and development of TCP/IP, how it relates to the OSI model, IP addressing, TCP and UDP protocols, and how connections are established and torn down using TCP. Key points covered include TCP/IP covering the network and transport layers, IP providing unreliable datagram delivery, TCP providing reliable byte-stream delivery, and the three-way handshake used to open TCP connections.
Cyber Warfare is the current single greatest emerging threat to National Security. Network security has become an essential component of any computer network. As computer networks and systems become ever more fundamental to modern society, concerns about security has become increasingly important. There are a multitude of different applications open source and proprietary available for the protection +-system administrator, to decide on the most suitable format for their purpose requires knowledge of the available safety measures, their features and how they affect the quality of service, as well as the kind of data they will be allowing through un flagged. A majority of methods currently used to ensure the quality of a networks service are signature based. From this information, and details on the specifics of popular applications and their implementation methods, we have carried through the ideas, incorporating our own opinions, to formulate suggestions on how this could be done on a general level. The main objective was to design and develop an Intrusion Detection System. While the minor objectives were to; Design a port scanner to determine potential threats and mitigation techniques to withstand these attacks. Implement the system on a host and Run and test the designed IDS. In this project we set out to develop a Honey Pot IDS System. It would make it easy to listen on a range of ports and emulate a network protocol to track and identify any individuals trying to connect to your system. This IDS will use the following design approaches: Event correlation, Log analysis, Alerting, and policy enforcement. Intrusion Detection Systems (IDSs) attempt to identify unauthorized use, misuse, and abuse of computer systems. In response to the growth in the use and development of IDSs, we have developed a methodology for testing IDSs. The methodology consists of techniques from the field of software testing which we have adapted for the specific purpose of testing IDSs. In this paper, we identify a set of general IDS performance objectives which is the basis for the methodology. We present the details of the methodology, including strategies for test-case selection and specific testing procedures. We include quantitative results from testing experiments on the Network Security Monitor (NSM), an IDS developed at UC Davis. We present an overview of the software platform that we have used to create user-simulation scripts for testing experiments. The platform consists of the UNIX tool expect and enhancements that we have developed, including mechanisms for concurrent scripts and a record-and-replay feature. We also provide background information on intrusions and IDSs to motivate our work.
This document provides an overview of IP addressing concepts. It discusses what an IP address is, including that IPv4 addresses are 32-bit numbers written in dotted decimal notation. It covers network prefixes and host numbers, classes of IP addresses, and subnetting. The objectives are to understand what an IP address is, network prefixes and host numbers, internet addresses, and the concepts of subnetting and no subnetting. Key points covered include the five classes of IPv4 addresses and how they differ in the number of hosts allowed per network.
Gourav Salla presented on Address Resolution Protocol (ARP). ARP is used to map IP addresses to MAC addresses so devices can communicate on a local network. It works by broadcasting an ARP request packet containing the target IP address. The device with that IP address responds with its MAC address. This address resolution allows packets for that destination to be sent directly using layer 2 addressing. ARP caches entries to avoid repeating the lookup for frequent communication between devices on the same subnet.
The document discusses Address Resolution Protocol (ARP) and Reverse Address Resolution Protocol (RARP). It provides examples of how ARP is used to map IP addresses to MAC addresses on local networks and how RARP is used for the opposite mapping. It also includes diagrams of ARP and RARP packets and operations. The examples show how ARP and RARP are used and how their data structures are updated as new address mappings are learned or cached entries time out.
This document discusses ARP and RARP protocols. ARP is used to map IP addresses to MAC addresses on local networks. It works by broadcasting ARP requests and unicasting replies. RARP is used in the opposite direction, to map a device's MAC address to its IP address. Examples are given of how an ARP cache works, including entries for pending, resolved, and free states. RARP has been replaced by BOOTP and DHCP for providing additional configuration info like subnet masks.
This document discusses several common computer network protocols: CIDR for routing IP addresses more efficiently; NAT for sharing public IP addresses among private networks; ICMP for error detection; ARP for mapping IP addresses to MAC addresses; RARP and BOOTP as predecessors to DHCP for dynamically assigning private IP addresses; and DHCP, the current standard dynamic host configuration protocol.
This document provides an overview of the Address Resolution Protocol (ARP). It defines ARP as a network layer protocol that maps IP addresses to MAC addresses, allowing communication within a local area network. Key points include:
- ARP resolves logical IP addresses to physical MAC addresses to allow communication on the data link layer.
- IP and MAC addresses are respectively logical and physical identifiers for devices on a network.
- The ARP packet format and work procedure of ARP caching are described.
- ARP requests are broadcast to find MAC addresses, and ARP responses provide the discovered addresses.
- A drawback of ARP is that it is vulnerable to spoofing and denial of service attacks.
This document discusses ARP and RARP protocols. ARP associates IP addresses with physical addresses to allow communication on a LAN. RARP performs the inverse, associating physical addresses with IP addresses. The document includes objectives, figures illustrating ARP and RARP operation and positioning in the TCP/IP stack, examples of ARP cache usage, and details on ARP and RARP packet formats and processing. It aims to explain the need, components, and interactions of the ARP and RARP protocols.
This document provides a summary of network protocols. It defines a network as a set of connected devices that can send and receive data. It explains that network protocols establish detailed rules for how computer systems exchange information. The document then overview Reverse Address Resolution Protocol (RARP) and several other key network protocols, including Internet Protocol (IP), Address Resolution Protocol (ARP), Internet Group Message Protocol (IGMP), and Internet Control Message Protocol (ICMP). For each protocol, it provides high-level descriptions of their functions and operations in 2 sentences or less.
ARP (Address Resolution Protocol) maps logical IP addresses to physical MAC addresses. When a host wants to send data to another host locally, it first broadcasts an ARP request containing the target IP address. The target host responds with its MAC address in an ARP reply, which the requesting host uses to update its ARP table and directly address future communications.
Overview of RARP, BOOTP, DHCP and PXE protocols for dynamic IP address assignment.
Dynamic IP address assignment to a host (or interface) is a common problem in TCP/IP based networks.
Manual and static assignment of IP addresses does not scale well and becomes a labor intensive task with a growing number of hosts.
An early approach for dynamic IP address assignment was RARP (Reverse ARP) which ran directly on the Ethernet protocol layer.
The many problems of RARP such as the inability to be routed between subnets were solved with BOOTP (Bootstrap Protocol).
BOOTP, however, ended to have its own set of limitations like lack of a lease time for IP addresses.
DHCP (Dynamic Host Configuration Protocol) was therefore defined as an extension to BOOTP.
DHCP is backward compatible with BOOTP thus allowing some degree of interoperability between the 2 protocols.
The state-of-the-art protocol for dynamic IP address assignment is, however, is DHCP.
DHCPv6 is an adaption of DHCP for IPv6 based networks.
This document discusses several internet protocols, including ARP and RARP. ARP is used to convert IP addresses to physical addresses like Ethernet addresses. It operates below the network layer to interface between OSI layers. A host broadcasts an ARP request to obtain another device's physical address. RARP is used to resolve an IP address from a given hardware address. It has been replaced by newer protocols but was used by clients to request IP addresses from a network.
ARP spoofing allows an attacker to intercept or modify communications between two hosts on a local network by falsifying ARP responses and changing a target's ARP cache entries. The attacker sends spoofed ARP replies associating the target's IP addresses with the attacker's MAC address, intercepting traffic intended for another host. This enables man-in-the-middle attacks where the attacker can sniff or modify intercepted traffic before forwarding it. Defenses include static ARP entries and port security on switches, but weaknesses remain, especially on networks using dynamic addressing protocols like DHCP.
Address Resolution Protocol (ARP) is used to map network layer addresses (IP addresses) to data link layer addresses (MAC addresses). This process is necessary because communication between devices on a local network uses MAC addresses, while routing and forwarding between networks uses IP addresses. ARP works by broadcasting a request packet containing the target IP address, and the device with that IP address responds with its MAC address. If the MAC address is unknown, ARP uses a broadcast query to determine the address dynamically, while direct mapping provides a way to statically determine addresses through a formula.
Overview of IP routing protocols, packet forwarding and proxy ARP.
The principle of IP routing proved to be very flexible and scalable in the growth of the Internet and TCP/IP based networks.
IP routing denotes protocols for exchanging IP address range reachability like RIP, BGP and OSPF.
In contrast to IP routing, IP packet forwarding collectively means all functions performed when an IP router receives a packet and forwards it over the output interface indicated by an IP route in the routing table.
When an IP router performs a route lookup, it calculates a route decision based on different properties like prefix (mask) length, route precedence and metrics.
Routing protocols for exchanging route information can be coarsely classified as distance vector and link state protocols. Distance vector protocols like RIP (Routing Information Protocol) exchange information about the path cost to specific targets (IP address ranges). Routers that talk distance vector protocols receive reachability information about all sub-networks indirectly from neighboring routers.
In contrast to distance vector protocols, link state protocols like OSPF disseminate information about the link state of each router link in a network to all routers in the network. Thus link state protocols tend to converge faster to topology changes since all routers have firsthand information of the topology of the network.
Proxy ARP may be a convenient solution when it comes to add additional subnets without having to add routes to routers and hosts. A proxy ARP enabled router would answer ARP requests on behalf of the targeted hosts mimicking a local network access to the requesting host.
This document presents a technique to identify the correct IP to MAC address mapping when an attacker is performing ARP spoofing. It discusses limitations of existing probe packet-based detection techniques when facing a strong attacker. The proposed technique generates broadcast ARP requests to identify the correct mapping, even if the attacker can modify the protocol stack. Experimental results show the technique can correctly identify the attacker in both weak and strong attacking environments with only a small increase in network traffic overhead.
This document presents on the Reverse Address Resolution Protocol (RARP). It defines RARP as a protocol used to find the logical address for a machine that knows only its physical address. It describes how RARP works to dynamically map physical addresses to logical addresses, as ARP maps logical to physical addresses. The document outlines the uses of RARP and its limitations that led to its replacement by other protocols like BOOTP and DHCP.
This document discusses BOOTP and DHCP protocols. It provides objectives that will be covered, including the types of information required by systems on boot-up and how BOOTP and DHCP operate. BOOTP provides IP addresses and other network configuration details, while DHCP provides static and dynamic address allocation manually or automatically. The document includes figures illustrating operations, packet formats, and state diagrams for both protocols.
The document discusses ARP and RARP protocols. It provides examples of how ARP is used to dynamically map IP addresses to physical addresses in order to send packets between hosts on a local network. ARP broadcasts a request packet to find a target host's physical address and caches the result. RARP is used to obtain an IP address from a known physical address. Figures show the ARP process, encapsulation, different usage cases, and an example ARP exchange between two hosts.
The document discusses the Internet Control Message Protocol (ICMP). ICMP provides error reporting, congestion reporting, and first-hop router redirection. It uses IP to carry its data end-to-end and is considered an integral part of IP. ICMP messages are encapsulated in IP datagrams and are used to report errors in IP datagrams, though some errors may still result in datagrams being dropped without a report. ICMP defines various message types including error messages like destination unreachable and informational messages like echo request and reply.
The document discusses Address Resolution Protocol (ARP) and gratuitous ARP. ARP is used to map IP addresses to MAC addresses on a local network. It maintains an ARP cache table mapping addresses. Gratuitous ARP occurs when a device sends an ARP request for its own IP address, broadcasting its IP-MAC mapping to update switches and detect duplicate IP addresses on the network. It helps ensure unique IP addresses and informs switches of end device locations. The document provides examples of gratuitous ARP detecting and resolving a duplicate IP address scenario.
The document provides an overview of TCP/IP (Transmission Control Protocol/Internet Protocol). It discusses the history and development of TCP/IP, how it relates to the OSI model, IP addressing, TCP and UDP protocols, and how connections are established and torn down using TCP. Key points covered include TCP/IP covering the network and transport layers, IP providing unreliable datagram delivery, TCP providing reliable byte-stream delivery, and the three-way handshake used to open TCP connections.
Cyber Warfare is the current single greatest emerging threat to National Security. Network security has become an essential component of any computer network. As computer networks and systems become ever more fundamental to modern society, concerns about security has become increasingly important. There are a multitude of different applications open source and proprietary available for the protection +-system administrator, to decide on the most suitable format for their purpose requires knowledge of the available safety measures, their features and how they affect the quality of service, as well as the kind of data they will be allowing through un flagged. A majority of methods currently used to ensure the quality of a networks service are signature based. From this information, and details on the specifics of popular applications and their implementation methods, we have carried through the ideas, incorporating our own opinions, to formulate suggestions on how this could be done on a general level. The main objective was to design and develop an Intrusion Detection System. While the minor objectives were to; Design a port scanner to determine potential threats and mitigation techniques to withstand these attacks. Implement the system on a host and Run and test the designed IDS. In this project we set out to develop a Honey Pot IDS System. It would make it easy to listen on a range of ports and emulate a network protocol to track and identify any individuals trying to connect to your system. This IDS will use the following design approaches: Event correlation, Log analysis, Alerting, and policy enforcement. Intrusion Detection Systems (IDSs) attempt to identify unauthorized use, misuse, and abuse of computer systems. In response to the growth in the use and development of IDSs, we have developed a methodology for testing IDSs. The methodology consists of techniques from the field of software testing which we have adapted for the specific purpose of testing IDSs. In this paper, we identify a set of general IDS performance objectives which is the basis for the methodology. We present the details of the methodology, including strategies for test-case selection and specific testing procedures. We include quantitative results from testing experiments on the Network Security Monitor (NSM), an IDS developed at UC Davis. We present an overview of the software platform that we have used to create user-simulation scripts for testing experiments. The platform consists of the UNIX tool expect and enhancements that we have developed, including mechanisms for concurrent scripts and a record-and-replay feature. We also provide background information on intrusions and IDSs to motivate our work.
This document provides an overview of IP addressing concepts. It discusses what an IP address is, including that IPv4 addresses are 32-bit numbers written in dotted decimal notation. It covers network prefixes and host numbers, classes of IP addresses, and subnetting. The objectives are to understand what an IP address is, network prefixes and host numbers, internet addresses, and the concepts of subnetting and no subnetting. Key points covered include the five classes of IPv4 addresses and how they differ in the number of hosts allowed per network.
A queue is a first-in, first-out (FIFO) data structure where elements are added at the rear and removed from the front. Real-world examples of queues include lines at ticket windows and luggage check machines where the first person/luggage in is served first. In computing, queues are useful for tasks waiting to access resources like printers or for scheduling jobs on a CPU. Common queue operations are enqueue to add an element to the rear and dequeue to remove an element from the front.
IP addressing provides a unique identifier for devices on a network. There are two main types - static and dynamic. IP addresses are 32-bit numbers divided into network and host portions. Classes A, B, and C determine the portions. Subnetting and CIDR allow flexible allocation. Special addresses like private and link-local are never used publicly. IPv6 uses 128-bit addressing. Tools like ping, tracert, and pathping test network connectivity. Mobile IP uses home and care-of addresses to maintain connectivity as devices move between networks, with home and foreign agents facilitating address changes. Inefficiency can occur via double crossing or triangle routing.
The document discusses IP addressing and subnetting. It begins by defining IP addresses and their structure as 32-bit addresses divided into four octets written in dotted decimal notation. It then covers IP address classes, identifying the class of example addresses. The document also discusses network IDs and host IDs, default subnet masks, and how to determine the appropriate subnet mask based on the number of required hosts. It provides examples of finding the network address given an IP address and subnet mask.
A queue is a non-primitive linear data structure that follows the FIFO (first-in, first-out) principle. Elements are added to the rear of the queue and removed from the front. Common operations on a queue include insertion (enqueue) and deletion (dequeue). Queues have many real-world applications like waiting in lines and job scheduling. They can be represented using arrays or linked lists.
This document provides an overview of cryptography. It begins with basic definitions related to cryptography and a brief history of its use from ancient times to modern ciphers. It then describes different types of ciphers like stream ciphers, block ciphers, and public key cryptosystems. It also covers cryptography methods like symmetric and asymmetric algorithms. Common types of attacks on cryptosystems like brute force, chosen ciphertext, and frequency analysis are also discussed.
IP addresses are 32-bit numbers that uniquely identify devices on a network. They allow for file transfers and email communication using the Internet Protocol. There are five classes of IP addresses - A, B, C, D, and E - which are divided into ranges to define large, medium, and small networks. Users can determine the IP address of their own device or other computers and websites using commands like ipconfig and ping.
Cryptography is the science of using mathematics to encrypt and decrypt data.
Cryptography enables you to store sensitive information or transmit it across insecure networks so that it cannot be read by anyone except the intended recipient.
This PPT explains about the term "Cryptography - Encryption & Decryption". This PPT is for beginners and for intermediate developers who want to learn about Cryptography. I have also explained about the various classes which .Net provides for encryption and decryption and some other terms like "AES" and "DES".
This document provides an overview of cryptography. It defines cryptography as the science of securing messages from attacks. It discusses basic cryptography terms like plain text, cipher text, encryption, decryption, and keys. It describes symmetric key cryptography, where the same key is used for encryption and decryption, and asymmetric key cryptography, which uses different public and private keys. It also covers traditional cipher techniques like substitution and transposition ciphers. The document concludes by listing some applications of cryptography like e-commerce, secure data, and access control.
The document provides an overview of encryption, including what it is, why it is used, and how it works. Encryption is the process of encoding information to protect it, while decryption is decoding the information. There are two main types of encryption: asymmetric encryption which uses public and private keys, and symmetric encryption which uses a shared key. Encryption is used to secure important data like health records, credit cards, and student information from being stolen or read without permission. It allows senders to encode plain text into ciphertext using a key.
This document provides an overview of Ethernet and Address Resolution Protocol (ARP) concepts. It describes the operation of the Ethernet sublayers including the logical link control (LLC) and media access control (MAC) sublayers. It explains how ARP works to resolve IP addresses to MAC addresses through ARP requests and maintaining an ARP table. It also discusses how ARP entries can be removed from the ARP table over time or manually.
The document discusses several Internet protocols:
- IP prepares packets for transmission across the Internet and provides unreliable packet delivery. IPv6 was created to address issues with IPv4 like exhaustion of addresses.
- ARP resolves IP addresses to hardware addresses on local networks and maintains address mappings in caches.
- ICMP provides error reporting and network monitoring functions to support IP.
- TCP provides reliable data transmission and UDP provides simple transmission of datagrams.
This document provides an introduction to various protocols related to electronic commerce and the internet. It discusses IP addressing and how IP addresses are assigned to devices. It then explains protocols like ARP, RARP, BOOTP, DHCP, and ICMP that are used to map IP addresses to hardware addresses, assign IP addresses, and handle network errors and messages.
The document summarizes the OSI network layer and TCP/IP model Internet layer. It describes how layer 3, the network layer, is responsible for routing packets from source to destination by adding addressing and routing. It focuses on IP version 4, the most common network layer protocol, explaining its packet header fields and how routers use IP addresses and routing tables to forward packets between networks. It also discusses techniques for dividing networks, such as hierarchical addressing and static versus dynamic routing protocols.
Basic Introduction to Technology (networking).pdftthind
The document provides an overview of networking concepts and components. It begins with basic definitions of networks and networking. It then describes common networking devices like hubs, switches, routers, and network cards. It covers networking cables, IPv4 addressing, routing protocols like RIP and EIGRP, redistribution between protocols, ACLs, NAT, VPN tunnels, and Frame Relay. It concludes with an example implementation of a VPN tunnel between two routers.
The document discusses TCP/IP basics and networking concepts. It provides an overview of the OSI model and describes the layers from physical to application. It then focuses on the lower layers including Ethernet, IP addressing, ARP, and introduces TCP and UDP at the transport layer.
- The TCP/IP model was created by the Department of Defense to provide reliable networking and data integrity during disasters. It is now the predominant networking model used today.
- The TCP/IP model layers correspond to layers in the OSI model. Key protocols at each TCP/IP layer include IP, TCP, UDP, ARP, and Ethernet at the network/data link layers.
- TCP provides reliable, connection-oriented communications using sequence numbers, acknowledgments, and retransmissions. UDP provides simpler, connectionless delivery without guarantees.
TCP/IP is a protocol suite that includes IP, TCP, and UDP. IP provides connectionless and unreliable delivery of datagrams between hosts. TCP provides reliable, connection-oriented byte stream delivery between processes using ports. UDP offers minimal datagram delivery between processes using ports in an unreliable manner. The choice between TCP and UDP depends on the application's requirements for reliability and overhead.
This document discusses Address Resolution Protocol (ARP) spoofing attacks and proposes a new approach called ASHA to secure the ARP cache and prevent ARP spoofing. ARP spoofing allows attackers to associate their own MAC address with the IP address of another host, intercepting traffic. ASHA uses public/private key cryptography and TCP packets to securely exchange IP-MAC pairs between hosts and maintain the ARP cache in static mode. Experiments show that systems using ASHA are protected from ARP attacks.
This document proposes a new approach called ASHA to secure the Address Resolution Protocol (ARP) from spoofing attacks. ARP is currently vulnerable because it exchanges IP and MAC addresses in plain text, allowing attackers to spoof addresses. ASHA would install an agent between the IP and MAC layers on each host. The agent would encrypt the IP/MAC addresses when they are exchanged in ARP requests and replies using public/private key cryptography. It would also maintain the ARP cache in static mode for added security. The approach aims to protect ARP without requiring changes to the operating system kernel or use of additional servers. Experimental results showed the ASHA-installed systems were protected from ARP spoofing attacks.
The document provides an overview of the Address Resolution Protocol (ARP). It discusses:
- ARP allows mapping between a host's logical IP address to its physical MAC address on a local area network.
- Each device maintains an ARP cache table to map IP-MAC address pairs for other devices on the network. An ARP request is broadcast to resolve addresses and the responding device unicasts an ARP reply.
- ARP spoofing vulnerabilities exist since ARP does not authenticate requests/replies, allowing an attacker to poison a device's ARP cache with false address mappings and intercept network traffic.
The document discusses Address Resolution Protocol (ARP) which resolves IP addresses to MAC addresses on local area networks. It provides details on ARP requests, replies, and vulnerabilities like ARP poisoning. It also covers related topics like proxy ARP and variants of ARP used in other network types. The case study certificate is for a student who completed a case study on internet technology and ARP.
ARP is a protocol used to map IP addresses to MAC addresses. It works by broadcasting a request onto the network to discover the MAC address associated with a given IP address. The requesting device then stores the returned MAC address in its ARP cache for future use. ARP cache entries have a timeout period after which the mapping will be deleted. Reverse ARP and proxy ARP are variants that allow devices to discover their own IP address or resolve addresses across network segments. Gratuitous ARP broadcasts a device's MAC address upon startup. DHCP dynamically assigns IP configuration including the IP address, subnet mask, gateway, and DNS to devices on a network.
Introduction to the Network Layer: Network layer services, packet switching, network layer performance, IPv4 addressing, forwarding of IP packets, Internet Protocol, ICMPv4, Mobile IP Unicast Routing: Introduction, routing algorithms, unicast routing protocols. Next generation IP: IPv6 addressing, IPv6 protocol, ICMPv6 protocol, transition from IPv4 to IPv6. Introduction to the Transport Layer: Introduction, Transport layer protocols (Simple protocol, Stop-and-wait protocol, Go-Back-n protocol, Selective repeat protocol, Bidirectional protocols), Transport layer services, User datagram protocol, Transmission control protocol
A network connects two or more computers together. Networks are classified based on their topology, protocols, and architecture. Common topologies include bus, ring, and star. Protocols like Ethernet and Token Ring define how computers communicate. Architectures are either peer-to-peer or client/server. Devices connect directly in peer-to-peer while clients rely on a central server in a client/server network.
The document discusses the key aspects of the Internet Protocol (IP) including its connectionless delivery service, packet format and processing by routers. IP provides end-to-end delivery of packets across interconnected networks, with each packet containing a header for routing. Routers examine packet headers to forward packets via the best path towards the destination based on routing tables. IP itself provides a best-effort delivery service, while higher level protocols implement reliable connections.
The network layer is responsible for delivering packets from source to destination. It must know the topology of the subnet and choose appropriate paths. When sources and destinations are in different networks, the network layer must deal with these differences. The network layer uses logical addressing that is independent of the underlying physical network. Routing ensures packets are delivered through routers and switches from source to destination across interconnected networks.
This document discusses Ethernet switching and MAC address tables on switches. It provides information on Ethernet frames, MAC addressing, and how switches use MAC address tables to learn the ports associated with device MAC addresses to efficiently forward frames to their destinations. The document covers the basic components of Ethernet frames, unicast, broadcast, and multicast MAC addressing, and how switches build and use MAC address tables to associate MAC addresses with switch ports for frame forwarding.
The document discusses topics related to the network layer, including:
1. It describes virtual circuits and datagrams, which are two methods for transferring data across networks.
2. It covers IPv4 addressing concepts such as address space, notations, classful and classless addressing, subnetting, and network address translation.
3. It provides an overview of additional network layer topics like IPv6 addressing, routing algorithms, internet control protocols, and routing protocols.
This document discusses physical layer aggregation to provide scalable bandwidth and resilience. It proposes applying the concepts of 802.3ah PME aggregation at the physical layer of existing 10GBASE PHYs. Packet fragmentation, distribution across multiple PHYs, and reassembly could increase bandwidth utilization compared to link aggregation above the MAC. Variable size fragmentation is most efficient. A control protocol would be needed to configure aggregations. Examples show default and reconfigured configurations using multiple 10GBASE-R PHYs aggregated to provide higher speeds. The approach could be used with various PHY types including multi-wavelength PHYs.
The SM IO module provides monitoring of auxiliary equipment such as climate control units through detailed information and alarms. When maintenance is performed using the information from SM IO, time and money can be saved especially for remotely located sites. The SM IO connects to the DC power system's control unit and monitors auxiliary units. Information and alarms regarding the auxiliary equipment can be monitored through a web browser or management software. Benefits include lower maintenance costs and higher availability through remote monitoring and control of site equipment.
The SM BAT supervision module monitors the condition and status of battery backups at telecom sites to provide information and alarms. It is installed on the DC power system and connected to the battery backup to measure voltages, current, and temperatures. This detailed battery backup information and any alarms can be monitored through a web browser or management software from a remote location. This allows maintenance to be optimized for remote sites to lower costs and increase battery backup availability through automated testing and monitoring.
The document discusses a Standard Control Unit (SCU) that provides remote monitoring, configuration, status information, and control of a DC power plant's voltage, current, and alarm levels. The SCU can be upgraded to an Advanced Control Unit (ACU) through a simple swap, allowing for more extensive monitoring and control of auxiliary equipment on site. Benefits of the SCU/ACU include minimized installation time, high quality failure information, true hot plug installation, quick failure analysis, and extended battery life through advanced battery management.
This document provides installation and setup instructions for the ACTURA 48 701z power system. It includes descriptions of the power system components, sub-assemblies, and system controller. Installation instructions are provided for unpacking, mounting, making AC and DC connections, installing batteries, and setting up communication. Technical specifications for the power system and its rectifier modules are also included in an annex.
This document provides installation and commissioning instructions for an Integrated Power Management Unit (IPMU). The IPMU integrates a switch mode power supply and power management unit to provide power from the mains or generator to critical loads like a battery bank and BTS equipment. The summary includes:
1. The IPMU receives power from the mains or generator, regulates the voltage with transformers, and provides power to rectifier modules and battery bank.
2. Commissioning involves checking voltages and connections between the IPMU, generator, battery bank, and critical loads. Alarms are also connected from the IPMU and switch mode power supply to alert operators.
3. Detailed wiring diagrams and instructions are provided
This document provides an introduction to Unix for computer science students at Old Dominion University. It discusses the history and evolution of operating systems like Unix and how they differ from Windows. Specifically, it explains that Unix was designed for multiprogramming and multiprocessing environments using terminals for input/output when networking and remote access were common. In contrast, Windows emerged later for standalone personal computers with graphics interfaces. The document aims to help students understand why the CS department uses Unix and the fundamental design of the Unix operating system.
This document provides an introduction to Unix including:
- An overview of the Unix operating system structure including the kernel, system calls, and how programs interact with the kernel.
- A description of the Unix file system structure as an inverted tree with directories and files represented as nodes.
- An explanation of Unix directories, files, and inodes, which contain metadata about each file.
- A brief definition of Unix programs as executable shell files, built-in shell commands, or compiled object code files.
This document provides an intermediate-level practical guide to using Unix. It covers topics such as redirecting standard input/output to files, filename substitution using wildcards, using shell variables, command substitution, and writing simple shell scripts. Examples are provided to illustrate how to use commands like date, ls, and echo to manipulate files and data. Shell programming concepts like conditional expressions and foreach loops are demonstrated in short scripts.
Mobile networks use radio frequencies to allow cellular devices to connect to a network of base stations. Base stations transmit and receive signals in frequency bands between 850-1900 MHz. As devices move between base station coverage areas, the network performs handoffs to transfer the connection seamlessly. Higher generations of cellular networks like 3G and 4G provide improved data speeds but still must handle user mobility effectively.
The document describes the ALS series of IP/PDH/SDH microwave radio systems. Key points:
- The ALS series provides native IP, PDH and SDH connectivity and is suitable for a wide range of network applications, from cost-sensitive to high-capacity backbone networks.
- It supports flexible interfaces including E1, Ethernet, and STM-1, and can evolve from pure TDM to pure IP networks.
- Nodal configurations allow connecting multiple hops in crowded stations simply and reduce equipment complexity.
Nokia siemens-networks-flexi-multiradio-base-station-data-sheetRaafat younis
The document describes the Flexi 3-sector RF module from Nokia Siemens Networks, which offers a multi-standard base station featuring GSM/EDGE, WCDMA/HSPA, and LTE technologies in a single hardware platform. It supports software upgrades between the different technologies and aims to improve efficiency, boost performance, and reduce costs for network operators. The Flexi module provides high capacity and integration density in a compact form factor.
Advanced control scheme of doubly fed induction generator for wind turbine us...IJECEIAES
This paper describes a speed control device for generating electrical energy on an electricity network based on the doubly fed induction generator (DFIG) used for wind power conversion systems. At first, a double-fed induction generator model was constructed. A control law is formulated to govern the flow of energy between the stator of a DFIG and the energy network using three types of controllers: proportional integral (PI), sliding mode controller (SMC) and second order sliding mode controller (SOSMC). Their different results in terms of power reference tracking, reaction to unexpected speed fluctuations, sensitivity to perturbations, and resilience against machine parameter alterations are compared. MATLAB/Simulink was used to conduct the simulations for the preceding study. Multiple simulations have shown very satisfying results, and the investigations demonstrate the efficacy and power-enhancing capabilities of the suggested control system.
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Slides from talk presenting:
Aleš Zamuda: Presentation of IEEE Slovenia CIS (Computational Intelligence Society) Chapter and Networking.
Presentation at IcETRAN 2024 session:
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Panel Session: Promoting Connection and Cooperation"
IEEE Slovenia GRSS
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3-6 June 2024, Niš, Serbia
KuberTENes Birthday Bash Guadalajara - K8sGPT first impressionsVictor Morales
K8sGPT is a tool that analyzes and diagnoses Kubernetes clusters. This presentation was used to share the requirements and dependencies to deploy K8sGPT in a local environment.
1. Address Resolution Protocol
Last Updated: January 30, 2013
The Address Resolution Protocol (ARP) feature performs a required function in IP routing. ARP finds the
hardware address, also known as Media Access Control (MAC) address, of a host from its known IP
address. ARP maintains a cache (table) in which MAC addresses are mapped to IP addresses. ARP is part
of all Cisco systems that run IP.
This feature module explains ARP for IP routing and the optional ARP features you can configure, such as
static ARP entries, timeout for dynamic ARP entries, clearing the cache, and proxy ARP.
• Finding Feature Information, page 1
• Information About the Address Resolution Protocol, page 1
• How to Configure the Address Resolution Protocol, page 6
• Configuration Examples for the Address Resolution Protocol, page 14
• Additional References, page 15
• Feature Information for the Address Resolution Protocol, page 16
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest caveats
and feature information, see Bug Search Tool and the release notes for your platform and software release.
To find information about the features documented in this module, and to see a list of the releases in which
each feature is supported, see the feature information table at the end of this module.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Information About the Address Resolution Protocol
• Layer 2 and Layer 3 Addressing, page 2
• Overview of the Address Resolution Protocol, page 3
• ARP Caching, page 4
• Static and Dynamic Entries in the ARP Cache, page 4
• Devices That Do Not Use ARP, page 4
Americas Headquarters:
Cisco Systems, Inc., 170 West Tasman Drive, San Jose, CA 95134-1706 USA
2. • Inverse ARP, page 4
• Reverse ARP, page 5
• Proxy ARP, page 5
• Serial Line Address Resolution Protocol, page 6
Layer 2 and Layer 3 Addressing
IP addressing occurs at Layer 2 (data link) and Layer 3 (network) of the Open System Interconnection
(OSI) reference model. OSI is an architectural network model developed by ISO and ITU-T that consists of
seven layers, each of which specifies particular network functions such as addressing, flow control, error
control, encapsulation, and reliable message transfer.
Layer 2 addresses are used for local transmissions between devices that are directly connected. Layer 3
addresses are used for indirectly connected devices in an internetwork environment. Each network uses
addressing to identify and group devices so that transmissions can be sent and received. Ethernet (802.2,
802.3, Ethernet II, and Subnetwork Access Protocol [SNAP]), Token Ring, and Fiber Distributed Data
Interface (FDDI) use media access control (MAC) addresses that are “burned in” to the network interface
card (NIC). The most commonly used network types are Ethernet II and SNAP.
Note For the supported interface types, see the data sheet for your hardware platform.
In order for devices to be able to communicate with each when they are not part of the same network, the
48-bit MAC address must be mapped to an IP address. Some of the Layer 3 protocols used to perform the
mapping are:
• Address Resolution Protocol (ARP)
• Reverse ARP (RARP)
• Serial Line ARP (SLARP)
• Inverse ARP
For the purposes of IP mapping, Ethernet, Token Ring, and FDDI frames contain the destination and source
addresses. Frame Relay and Asynchronous Transfer Mode (ATM) networks, which are packet-switched,
data packets take different routes to reach the same destination. At the receiving end, the packet is
reassembled in the correct order.
In a Frame Relay network, there is one physical link that has many logical circuits called virtual circuits
(VCs). The address field in the frame contains a data-link connection identifier (DLCI), which identifies
each VC. For example, in the figure below, the Frame Relay switch to which device Fred is connected
receives frames; the switch forwards the frames to either Barney or Betty based on the DLCI that identifies
each VC. So Fred has one physical connection but multiple logical connections.
Figure 1 Frame Relay Network
135219
Barney
Betty
Fred
Packet
What do I do? Look
at the address!
Layer 2 and Layer 3 Addressing
Information About the Address Resolution Protocol
2
3. ATM networks use point-to-point serial links with the High-Level Data Link Control (HDLC) protocol.
HDLC includes a meaningless address field included in five bytes of the frame header frame with the
recipient implied since there can be only one.
Overview of the Address Resolution Protocol
The Address Resolution Protocol (ARP) was developed to enable communications on an internetwork and
is defined by RFC 826. Layer 3 devices need ARP to map IP network addresses to MAC hardware
addresses so that IP packets can be sent across networks. Before a device sends a datagram to another
device, it looks in its ARP cache to see if there is a MAC address and corresponding IP address for the
destination device. If there is no entry, the source device sends a broadcast message to every device on the
network. Each device compares the IP address to its own. Only the device with the matching IP address
replies to the sending device with a packet containing the MAC address for the device (except in the case of
“proxy ARP”). The source device adds the destination device MAC address to its ARP table for future
reference, creates a data-link header and trailer that encapsulates the packet, and proceeds to transfer the
data. The figure below illustrates the ARP broadcast and response process.
Figure 2 ARP Process
I need the address of 10.1.1.2. I heard that broadcast. The message is for me.
Here is my MAC address: 00:1D:7E:1D:00:01.
Barney
135075
Fred
When the destination device lies on a remote network, one beyond another Layer 3 device, the process is
the same except that the sending device sends an ARP request for the MAC address of the default gateway.
After the address is resolved and the default gateway receives the packet, the default gateway broadcasts
the destination IP address over the networks connected to it. The Layer 3 device on the destination device
network uses ARP to obtain the MAC address of the destination device and delivers the packet.
Encapsulation of IP datagrams and ARP requests and replies on IEEE 802 networks other than Ethernet use
Subnetwork Access Protocol (SNAP).
The ARP request message has the following fields:
• HLN—Hardware address length. Specifies how long the hardware addresses are in the message. For
IEEE 802 MAC addresses (Ethernet) the value is 6.
• PLN—Protocol address length. Specifies how long the protocol (Layer 3) addresses are in the
message. For IPv4, the value is 4.
• OP—Opcode. Specifies the nature of the message by code:
◦ 1—ARP request.
◦ 2—ARP reply.
◦ 3 through 9—RARP and Inverse ARP requests and replies.
• SHA—Sender hardware address. Specifies the Layer 2 hardware address of the device sending the
message.
• SPA—Sender protocol address. Specifies the IP address of the sending device.
• THA—Target hardware address. Specifies the Layer 2 hardware address of the receiving device.
• TPA—Target protocol address. Specifies the IP address of the receiving device.
Overview of the Address Resolution Protocol
Information About the Address Resolution Protocol
3
4. ARP Caching
Because the mapping of IP addresses to media access control (MAC) addresses occurs at each hop (Layer 3
device) on the network for every datagram sent over an internetwork, performance of the network could be
compromised. To minimize broadcasts and limit wasteful use of network resources, Address Resolution
Protocol (ARP) caching was implemented.
ARP caching is the method of storing network addresses and the associated data-link addresses in memory
for a period of time as the addresses are learned. This minimizes the use of valuable network resources to
broadcast for the same address each time a datagram is sent. The cache entries must be maintained because
the information could become outdated, so it is critical that the cache entries are set to expire periodically.
Every device on a network updates its tables as addresses are broadcast.
There are static ARP cache entries and dynamic ARP cache entries. Static entries are manually configured
and kept in the cache table on a permanent basis. Static entries are best for devices that have to
communicate with other devices usually in the same network on a regular basis. Dynamic entries are added
by Cisco software, kept for a period of time, and then removed.
Static and Dynamic Entries in the ARP Cache
Static routing requires an administrator to manually enter into a table IP addresses, subnet masks, gateways,
and corresponding Media Access Control (MAC) addresses for each interface of each device. Static routing
enables more control but requires more work to maintain the table. The table must be updated each time
routes are added or changed.
Dynamic routing uses protocols that enable the devices in a network to exchange routing table information
with each other. The table is built and changed automatically. No administrative tasks are needed unless a
time limit is added, so dynamic routing is more efficient than static routing. The default time limit is 4
hours. If the network has many routes that are added and deleted from the cache, the time limit should be
adjusted.
The routing protocols that dynamic routing uses to learn routes, such as distance-vector and link-state
routing protocols, are beyond the scope of this document.
Devices That Do Not Use ARP
When a network is divided into two segments, a bridge joins the segments and filters traffic to each
segment based on Media Access Control (MAC) addresses. The bridge builds its own address table, which
uses MAC addresses only, as opposed to a router, which has an Address Resolution Protocol (ARP) cache
that contains both IP addresses and the corresponding MAC addresses.
Passive hubs are central-connection devices that physically connect other devices in a network. They send
messages out all ports to the devices and operate at Layer 1, but they do not maintain an address table.
Layer 2 switches determine which port is connected to a device to which the message is addressed and send
the message only to that port, unlike a hub, which sends the message out all its ports. However, Layer 3
switches are routers that build an ARP cache (table).
Inverse ARP
Inverse ARP, which is enabled by default in ATM networks, builds an ATM map entry and is necessary to
send unicast packets to a server (or relay agent) on the other end of a connection. Inverse ARP is supported
only for the aal5snap encapsulation type.
ARP Caching
Information About the Address Resolution Protocol
4
5. For multipoint interfaces, an IP address can be acquired using other encapsulation types because broadcast
packets are used. However, unicast packets to the other end will fail because there is no ATM map entry
and thus DHCP renewals and releases also fail.
For more information about Inverse ARP and ATM networks, see the “Configuring ATM” feature module
in the Asynchronous Transfer Mode Configuration Guide.
Reverse ARP
Reverse ARP (RARP) as defined by RFC 903 works the same way as the Address Resolution Protocol
(ARP), except that the RARP request packet requests an IP address instead of a media access control
(MAC) address. RARP often is used by diskless workstations because this type of device has no way to
store IP addresses to use when they boot. The only address that is known is the MAC address because it is
burned in to the hardware.
RARP requires a RARP server on the same network segment as the device interface. The figure below
illustrates how RARP works.
Figure 3 RARP Process
I am device A and sending
a broadcast that uses my
hardware address.
Can somone on the network
tell me what my IP address is?
Okay, your hardware address
is 00:1D:7E:1D:00:01 and
your IP address is 10.0.0.2
RARP server
135218
Device A
Because of the limitations with RARP, most businesses use Dynamic Host Configuration Protocol (DHCP)
to assign IP addresses dynamically. DHCP is cost-effective and requires less maintenance than RARP. The
most important limitations with RARP are as follows:
• Because RARP uses hardware addresses, if the internetwork is large with many physical networks, a
RARP server must be on every segment with an additional server for redundancy. Maintaining two
servers for every segment is costly.
• Each server must be configured with a table of static mappings between the hardware addresses and
the IP addresses. Maintenance of the IP addresses is difficult.
• RARP only provides IP addresses of the hosts but not subnet masks or default gateways.
Cisco software attempts to use RARP if it does not know the IP address of an interface at startup to respond
to RARP requests that it is able to answer. The AutoInstall feature of the software automates the
configuration of Cisco devices.
AutoInstall supports RARP and enables a network manager to connect a new device to a network, turn it
on, and automatically load a pre-existing configuration file. The process begins when no valid
configuration file is found in NVRAM. For more information about AutoInstall, see the Configuration
Fundamentals Configuration Guide.
Proxy ARP
Proxy Address Resolution Protocol, as defined in RFC 1027, was implemented to enable devices that are
separated into physical network segments connected by a router in the same IP network or subnetwork to
Reverse ARP
Information About the Address Resolution Protocol
5
6. resolve IP-to-MAC addresses. When devices are not in the same data link layer network but are in the same
IP network, they try to transmit data to each other as if they were on the local network. However, the router
that separates the devices will not send a broadcast message because routers do not pass hardware-layer
broadcasts. Therefore, the addresses cannot be resolved.
Proxy ARP is enabled by default so the “proxy router” that resides between the local networks responds
with its MAC address as if it were the router to which the broadcast is addressed. When the sending device
receives the MAC address of the proxy router, it sends the datagram to the proxy router, which in turns
sends the datagram to the designated device.
Proxy ARP is invoked by the following conditions:
• The target IP address is not on the same physical network (LAN) on which the request is received.
• The networking device has one or more routes to the target IP address.
• All of the routes to the target IP address go through interfaces other than the one on which the request
is received.
When proxy ARP is disabled, a device responds to ARP requests received on its interface only if the target
IP address is the same as its IP address or if the target IP address in the ARP request has a statically
configured ARP alias.
Serial Line Address Resolution Protocol
Serial Line ARP (SLARP) is used for serial interfaces that use High-Level Data Link Control (HDLC)
encapsulation. A SLARP server, intermediate (staging) device, and another device providing a SLARP
service might be required in addition to a TFTP server. If an interface is not directly connected to a server,
the staging device is required to forward the address-resolution requests to the server. Otherwise, a directly
connected device with SLARP service is required. Cisco software attempts to use SLARP if it does not
know the IP address of an interface at startup to respond to SLARP requests that software is able to answer.
Cisco software automates the configuration of Cisco devices with the AutoInstall feature. AutoInstall
supports SLARP and enables a network manager to connect a new device to a network, turn it on, and
automatically load a pre-existing configuration file. The process begins when no valid configuration file is
found in NVRAM. For more information about AutoInstall, see the Configuration Fundamentals
Configuration Guide.
Note AutoInstall supports serial interfaces that use Frame Relay encapsulation.
How to Configure the Address Resolution Protocol
By default, the Address Resolution Protocol (ARP) feature is enabled and is set to use Ethernet
encapsulation. Perform the following tasks to change or verify ARP functionality:
• Enabling the Interface Encapsulation, page 7
• Defining Static ARP Entries, page 8
• Setting an Expiration Time for Dynamic Entries in the ARP Cache, page 9
• Globally Disabling Proxy ARP, page 10
• Disabling Proxy ARP on an Interface, page 11
• Verifying the ARP Configuration, page 13
Serial Line Address Resolution Protocol
How to Configure the Address Resolution Protocol
6
7. Enabling the Interface Encapsulation
Perform this task to support a type of encapsulation for a specific network, such as Ethernet, Frame Relay,
FDDI, or Token Ring. When Frame Relay encapsulation is specified, the interface is configured for a
Frame Relay subnetwork with one physical link that has many logical circuits called virtual circuits (VCs).
The address field in the frame contains a data-link connection identifier (DLCI) that identifies each VC.
When SNAP encapsulation is specified, the interface is configured for FDDI or Token Ring networks.
Note The encapsulation type specified in this task should match the encapsulation type specified in the “Defining
Static ARP Entries” task.
SUMMARY STEPS
1. enable
2. configure terminal
3. interface type number
4. arp {arpa | frame-relay | snap}
5. end
DETAILED STEPS
Command or Action Purpose
Step 1 enable
Example:
Device> enable
Enables privileged EXEC mode.
• Enter your password if prompted.
Step 2 configure terminal
Example:
Device# configure terminal
Enters global configuration mode.
Step 3 interface type number
Example:
Device(config)# interface
GigabitEthernet0/0/0
Enters interface configuration mode.
Enabling the Interface Encapsulation
How to Configure the Address Resolution Protocol
7
8. Command or Action Purpose
Step 4 arp {arpa | frame-relay | snap}
Example:
Device(config-if)# arp arpa
Specifies the encapsulation type for an interface by type of
network, such as Ethernet, FDDI, Frame Relay, and Token Ring.
The keywords are as follows:
• arpa—Enables encapsulation for an Ethernet 802.3 network.
• frame-relay—Enables encapsulation for a Frame Relay
network.
• snap—Enables encapsulation for FDDI and Token Ring
networks.
Step 5 end
Example:
Device(config-if)# end
Returns to privileged EXEC mode.
Defining Static ARP Entries
Perform this task to define static mapping between an IP address (32-bit address) and a Media Access
Control (MAC) address (48-bit address) for hosts that do not support dynamic Address Resolution Protocol
(ARP). Because most hosts support dynamic address resolution, defining static ARP cache entries is
usually not required. Performing this task installs a permanent entry in the ARP cache that never times out.
The entries remain in the ARP table until they are removed using the no arp command or the clear arp
interface command for each interface.
Note The encapsulation type specified in this task should match the encapsulation type specified in the “Enabling
the Interface Encapsulation” task.
SUMMARY STEPS
1. enable
2. configure terminal
3. arp {ip-address | vrf vrf-name} hardware-address encap-type [interface-type]
4. end
DETAILED STEPS
Command or Action Purpose
Step 1 enable
Example:
Device> enable
Enables privileged EXEC mode.
• Enter your password if prompted.
Defining Static ARP Entries
How to Configure the Address Resolution Protocol
8
9. Command or Action Purpose
Step 2 configure terminal
Example:
Device# configure terminal
Enters global configuration mode.
Step 3 arp {ip-address | vrf vrf-name}
hardware-address encap-type
[interface-type]
Example:
Device(config)# arp 10.0.0.0
aabb.cc03.8200 arpa
Globally associates an IP address with a MAC address in the ARP cache.
• ip-address—IP address in four-part dotted decimal format corresponding to
the local data-link address.
• vrf vrf-name—Virtual routing and forwarding instance for a Virtual Private
Network (VPN). The vrf-name argument is the name of the VRF table.
• hardware-address—Local data-link address (a 48-bit address).
• encap-type—Encapsulation type for the static entry. The keywords are as
follows:
◦ arpa—For Ethernet interfaces.
◦ sap—For Hewlett Packard interfaces.
◦ smds—For Switched Multimegabit Data Service (SMDS) interfaces.
◦ snap—For FDDI and Token Ring interfaces.
◦ srp-a—Switch route processor side A (SRP-A) interfaces.
◦ srp-b—Switch route processor side B (SRP-B) interfaces.
Note Some keywords might not apply to your hardware platform.
• interface-type—(Optional) Interface type (for more information, use the
question mark (?) online help).
Step 4 end
Example:
Device(config)# end
Returns to privileged EXEC mode.
Setting an Expiration Time for Dynamic Entries in the ARP Cache
SUMMARY STEPS
1. enable
2. configure terminal
3. interface type number
4. arp timeout seconds
5. end
Setting an Expiration Time for Dynamic Entries in the ARP Cache
How to Configure the Address Resolution Protocol
9
10. DETAILED STEPS
Command or Action Purpose
Step 1 enable
Example:
Device> enable
Enables privileged EXEC mode.
• Enter your password if prompted.
Step 2 configure terminal
Example:
Device# configure terminal
Enters global configuration mode.
Step 3 interface type number
Example:
Device(config)# interface
GigabitEthernet0/0/0
Enters interface configuration mode.
Step 4 arp timeout seconds
Example:
Device(config-if)# arp timeout 30
Sets the length of time, in seconds, an Address Resolution
Protocol (ARP) cache entry stays in the cache. A value of zero
means that entries are never cleared from the cache. The default is
14400 seconds (4 hours).
Note If the network has frequent changes to cache entries,
change the default to a shorter time period.
Step 5 end
Example:
Device(config-if)# end
Returns to privileged EXEC mode.
Globally Disabling Proxy ARP
Proxy Address Resolution Protocol (ARP) is enabled by default; perform this task to globally disable proxy
ARP on all interfaces.
The Cisco software uses proxy ARP (as defined in RFC 1027) to help hosts with no knowledge of routing
determine the media access control (MAC) addresses of hosts on other networks or subnets. For example, if
hosts A and B are on different physical networks, host B does not receive the ARP broadcast request from
host A and cannot respond to it. However, if the physical network of host A is connected by a gateway to
the physical network of host B, the gateway sees the ARP request from host A.
Assuming that subnet numbers were assigned to correspond to physical networks, the gateway can also tell
that the request is for a host that is on a different physical network. The gateway can then respond for host
Globally Disabling Proxy ARP
How to Configure the Address Resolution Protocol
10
11. B, saying that the network address for host B is that of the gateway itself. Host A sees this reply, caches it,
and sends future IP packets for host B to the gateway.
The gateway forwards such packets to host B by using the configured IP routing protocols. The gateway is
also referred to as a transparent subnet gateway or ARP subnet gateway.
SUMMARY STEPS
1. enable
2. configure terminal
3. ip arp proxy disable
4. end
DETAILED STEPS
Command or Action Purpose
Step 1 enable
Example:
Device> enable
Enables privileged EXEC mode.
• Enter your password if prompted.
Step 2 configure terminal
Example:
Device# configure terminal
Enters global configuration mode.
Step 3 ip arp proxy disable
Example:
Device(config)# ip arp proxy disable
Disables proxy ARP on all interfaces.
• The ip arp proxy disable command overrides any proxy ARP interface
configuration.
• To reenable proxy ARP, use the no ip arp proxy disable command.
• You can also use the default ip proxy arp command to return to the
default proxy ARP behavior, which is enabled.
Step 4 end
Example:
Device(config)# end
Returns to privileged EXEC mode.
Disabling Proxy ARP on an Interface
Proxy Address Resolution Protocol (ARP) is enabled by default; perform this task to disable proxy ARP on
an interface.
Disabling Proxy ARP on an Interface
How to Configure the Address Resolution Protocol
11
12. SUMMARY STEPS
1. enable
2. configure terminal
3. interface type number
4. no ip proxy-arp
5. end
DETAILED STEPS
Command or Action Purpose
Step 1 enable
Example:
Device> enable
Enables privileged EXEC mode.
• Enter your password if prompted.
Step 2 configure terminal
Example:
Device# configure terminal
Enters global configuration mode.
Step 3 interface type number
Example:
Device(config)# interface GigabitEthernet0/0/0
Enters interface configuration mode.
Step 4 no ip proxy-arp
Example:
Device(config-if)# no ip proxy-arp
Disables proxy ARP on the interface.
• To reenable proxy ARP, use the ip proxy-arp command.
• You can also use the default ip proxy-arp command to
return to the default proxy ARP behavior on the interface,
which is enabled.
Step 5 end
Example:
Device(config-if)# end
Returns to privileged EXEC mode.
Disabling Proxy ARP on an Interface
How to Configure the Address Resolution Protocol
12
13. Verifying the ARP Configuration
SUMMARY STEPS
1. show interfaces
2. show arp
3. show ip arp
4. show processes cpu | include (ARP | PID)
DETAILED STEPS
Step 1 show interfaces
To display the type of Address Resolution Protocol (ARP) being used on a particular interface and also display the
ARP timeout value, use the show interfaces privileged EXEC command.
Example:
Device# show interfaces GigabitEthernet0/0/0
GigabitEthernet0/0/0 is up, line protocol is up
Hardware is SPA-8X1GE-V2, address is 001a.3045.4100 (bia 001a.3045.4100)
MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
reliability 255/255, txload ½55, rxload ½55
Encapsulation ARPA, loopback not set
Keepalive not supported
Full Duplex, 1000Mbps, link type is auto, media type is SX
output flow-control is off, input flow-control is off
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output 00:00:50, output hang never
Last clearing of ''show interface'' counters never
Input queue: 0/375/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
0 packets input, 0 bytes, 0 no buffer
Received 0 broadcasts (0 IP multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 0 multicast, 0 pause input
7998 packets output, 3074275 bytes, 0 underruns
0 output errors, 0 collisions, 4 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 pause output
0 output buffer failures, 0 output buffers swapped out
Step 2 show arp
Use the show arp privileged EXEC command to examine the contents of the ARP cache.
Example:
Device# show arp
Protocol Address Age (min) Hardware Addr Type Interface
Internet 10.1.1.1 43 001b.53e1.7201 ARPA GigabitEthernet0/0/6
Internet 10.1.1.2 29 0021.d8ab.0b00 ARPA GigabitEthernet0/0/6
Verifying the ARP Configuration
How to Configure the Address Resolution Protocol
13
14. Internet 10.1.2.1 80 001a.3045.4107 ARPA GigabitEthernet0/0/7
Internet 10.1.2.1 - 0000.0c02.a03c ARPA GigabitEthernet0/0/7
Step 3 show ip arp
Use the show ip arp privileged EXEC command to show IP entries. To remove all nonstatic entries from the ARP
cache, use the clear arp-cache privileged EXEC command.
Example:
Device# show ip arp
Protocol Address Age (min) Hardware Addr Type Interface
Internet 10.1.1.1 43 001b.53e1.7201 ARPA GigabitEthernet0/0/6
Internet 10.1.1.2 29 0021.d8ab.0b00 ARPA GigabitEthernet0/0/6
Internet 10.1.2.1 80 001a.3045.4107 ARPA GigabitEthernet0/0/7
Internet 10.1.2.1 - 0000.0c02.a03c ARPA GigabitEthernet0/0/7
Step 4 show processes cpu | include (ARP | PID)
Use the show processes cpu | include (ARP | PID) command to display ARP and RARP processes.
Example:
Device# show processes cpu | include (ARP | PID)
PID Runtime(ms) Invoked uSecs 5Sec 1Min 5Min TTY Process
9 46 515 89 0.00% 0.00% 0.00% 0 ARP Input
10 7 19078 0 0.00% 0.00% 0.00% 0 ARP Background
110 1 2 500 0.00% 0.00% 0.00% 0 IP ARP Adjacency
136 0 7 0 0.00% 0.00% 0.00% 0 ARP HA
182 0 8 0 0.00% 0.00% 0.00% 0 RARP Input
Configuration Examples for the Address Resolution Protocol
• Example: Static ARP Entry Configuration, page 14
• Example: Encapsulation Type Configuration, page 15
• Example: Proxy ARP Configuration, page 15
Example: Static ARP Entry Configuration
The following example shows how to configure a static Address Resolution Protocol (ARP) entry in the
cache by using the alias keyword, allowing the software to respond to ARP requests as if it were the
interface of the specified address:
arp 10.0.0.0 aabb.cc03.8200 alias
interface gigabitethernet0/0/0
Example: Static ARP Entry Configuration
Configuration Examples for the Address Resolution Protocol
14
15. Example: Encapsulation Type Configuration
The following example shows how to configure the encapsulation on the interface. The arpa keyword
indicates that interface is connected to an Ethernet 802.3 network:
interface gigabitethernet0/0/0
ip address 10.108.10.1 255.255.255.0
arp arpa
Example: Proxy ARP Configuration
The following example shows how to configure proxy ARP because it was disabled for the interface:
interface gigabitethernet0/0/0
ip proxy-arp
Additional References
Related Documents
Related Topic Document Title
Cisco IOS commands Cisco IOS Master Command List, All Releases
ARP commands Cisco IOS IP Addressing Services Command
Reference
AppleTalk addressing scheme Core Competence AppleTalk (white paper) at
www.corecom.com/html/appletalk.html
Authorized ARP “Configuring DHCP Services for Accounting and
Security” feature module in the IP Addressing:
DHCP Configuration Guide (part of the IP
Addressing Configuration Guide Library)
Inverse ARP and ATM networks “Configuring ATM” feature module in the
Asynchronous Transfer Mode Configuration Guide
AutoInstall Configuration Fundamentals Configuration Guide
RFCs
RFCs Title
RFC 826 Address Resolution Protocol
RFC 903 Reverse Address Resolution Protocol
RFC 1027 Proxy Address Resolution Protocol
Example: Encapsulation Type Configuration
Additional References
15
16. RFCs Title
RFC 1042 Standard for the Transmission of IP Datagrams
over IEEE 802 Networks
Technical Assistance
Description Link
The Cisco Support and Documentation website
provides online resources to download
documentation, software, and tools. Use these
resources to install and configure the software and
to troubleshoot and resolve technical issues with
Cisco products and technologies. Access to most
tools on the Cisco Support and Documentation
website requires a Cisco.com user ID and
password.
http://www.cisco.com/cisco/web/support/
index.html
Feature Information for the Address Resolution Protocol
The following table provides release information about the feature or features described in this module.
This table lists only the software release that introduced support for a given feature in a given software
release train. Unless noted otherwise, subsequent releases of that software release train also support that
feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Table 1 Feature Information for the Address Resolution Protocol
Feature Name Software Releases Feature Information
Address Resolution Protocol 12.2(15)T
15.0(1)S
Cisco IOS XE Release 2.1
Cisco IOS XE Release 3.2SE
The Address Resolution Protocol
(ARP) feature performs a
required function in IP routing.
ARP finds the hardware address,
also known as Media Access
Control (MAC) address, of a host
from its known IP address. ARP
maintains a cache (table) in which
MAC addresses are mapped to IP
addresses. ARP is part of all
Cisco systems that run IP.
Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S.
and other countries. To view a list of Cisco trademarks, go to this URL: www.cisco.com/go/trademarks.
Example: Proxy ARP Configuration
Feature Information for the Address Resolution Protocol
16