LAN and WAN Technologies Networking/internetworking Hardware ...


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LAN and WAN Technologies Networking/internetworking Hardware ...

  1. 1. LAN and WAN Technologies Networking/internetworking Hardware and Software Preliminaries in Network Design nd eie507 03/04 1
  2. 2. LAN and WAN Technologies LAN and WAN Technologies Networking and internetworking • Networking connecting of a computer or device (station, host, end-system, end-node) to another • Internetworking connecting of a network to another • Protocol a set of rules that controls how communications take place • Local Area Network (LAN): in general connecting stations geographically close to each other, e.g., within a building nd eie507 03/04 2
  3. 3. LAN and WAN Technologies • Wide Area Network (WAN): connecting multiple LANs Remark: Speed cannot be used to differentiate LANs from WANs any more. Traditionally, WANs were slower in speed than LANs. WANs can be faster than LANs nowadays however – the maximum speed of a WAN can be higher than that of a LAN. nd eie507 03/04 3
  4. 4. LAN and WAN Technologies Internetworking Technology
  5. 5. LAN and WAN Technologies Internetworking Technology The OSI Model
  6. 6. LAN and WAN Technologies Internetworking Technology The OSI Model • developed by the International Organization for Standardization (ISO)
  7. 7. LAN and WAN Technologies Internetworking Technology The OSI Model • developed by the International Organization for Standardization (ISO) • Seven layers: physical, data link, network, transport, session, pre- sentation, and application layers
  8. 8. LAN and WAN Technologies Internetworking Technology The OSI Model • developed by the International Organization for Standardization (ISO) • Seven layers: physical, data link, network, transport, session, pre- sentation, and application layers Physical defines the electrical, mechanical, procedural, and functional spe- cifications – transmission of (raw) signals (bits) Data link provides a reliable transit of data across a physical link, concerned with physical addressing, network topology, line discipline, error notification, the ordered delivery of frames, and flow control. nd eie507 03/04 4
  9. 9. LAN and WAN Technologies Network layer It provides connectivity and path selection between two end systems. Routing occurs at this layer. Protocols examples • TCP/IP Layer 3 and above protocol can be implemented on a LAN or WAN • LAN Protocols layers 1 and 2 of the OSI model Ethernet (derivatives: Fast Ethernet, Gigabit Ethernet and 10 Gigabit Ethernet) nd eie507 03/04 5
  10. 10. LAN and WAN Technologies Token ring FDDI (Fiber Distributed Data Interface) • WAN Protocols ATM X.25 Frame relay WAN Protocols operates at layers 1 and 2 of the OSI model • High Level Data Link Control (HDLC) HDLC is the primary protocol used for point-to-point serial lines • Frame Relay a packet-switched service nd eie507 03/04 6
  11. 11. LAN and WAN Technologies permanent virtual circuits (PVCs) switched virtual circuits (SVCs) lower rate, not so expensive • Asynchronous Transfer Mode (ATM) packet-switched network packets are of fixed length, called cells of 53 bytes long can carry both voice and data in general expensive • Integrated Services Digital Network (ISDN) a circuit-switched service digital dial-up, use the existing telephone local loop circuits offers two simultaneous connections (each of 64 kbps) • Digital Subscriber Line (DSL)/Cable modem rate of a few Mbps nd eie507 03/04 7
  12. 12. LAN and WAN Technologies Routed versus Routing Protocols • A routed protocol contains network, Layer 3, and addressing infor- mation enables the protocol to be directed from one network to another. • A routing protocol provides support to a routed protocol by sharing routing information distributed among routers. Routed protocols Routing Protocols TCP/IP RIP, OSPF, EIGRP,BGP IPX/SPX RIP, EIGRP, NLSP AppleTalk RTMP, EIGRP nd eie507 03/04 8
  13. 13. LAN and WAN Technologies Protocols in other layers Transmission Control Protocol/Internet Protocol (TCP/IP) • most commonly used protocol • used on the Internet exclusively TCP/IP protocols does not quite follow the OSI model. nd eie507 03/04 9
  14. 14. LAN and WAN Technologies OSI model TCP/IP Application FTP, HTTP, Telnet Presentation Session Transport TCP, UDP Network IP, ARP, ICMP Data link LAN/WAN Protocols Physical Physical • The Internet Protocol IP provides a best-effort, connectionless packet delivery service • The Address Resolution Protocol (ARP) used to discover the link address (e.g., IP address), or media access control (MAC, also known as hardware address) (e.g. Ethernet address) nd eie507 03/04 10
  15. 15. LAN and WAN Technologies • The Internet Control Message Protocol (ICMP) used to report network errors, refer to the ping command. TCP/IP Transport layer • the basis for all user data traffic • TCP TCP is a connection-oriented. • UDP UDP is a connectionless protocol. nd eie507 03/04 11
  16. 16. LAN and WAN Technologies TCP/IP application layer • File Transfer Protocol (FTP) to transfer files between hosts • Hypertext Transfer Protocol (HTTP) web page access • Telnet a terminal emulation application TCP/IP Routing Protocols • RIP the first TCP/IP routing protocol nd eie507 03/04 12
  17. 17. LAN and WAN Technologies distance vector protocol, uses a hop count metric at most 15 hops does not support multiple subnet masks RIP version 2 ∗ enables multiple subnet masks, 255 hops ∗ a classless protocol • Interior Gateway Routing Protocol (IGRP) Cisco proprietary distance vector routing protocol The Enhanced IGRP (EIGRP) ∗ integrates several link-state ∗ capabilities with several distance vector capabilities ∗ supports multiple subnet masks and is a classless protocol nd eie507 03/04 13
  18. 18. LAN and WAN Technologies • Open Shortest Path First (OSPF) a link-state routing protocol supports multiple subnet masks a classless protocol supports an unlimited number of hops • The Border Gateway Protocol (BGP) the routing protocol of the Internet performs routing between multiple autonomous systems (ASs) also a classless protocol nd eie507 03/04 14
  19. 19. LAN and WAN Technologies IP Addressing • An IP address is composed of 32 bits. • can be represented in binary dotted or decimal dotted artificially inserting three dots to divide the 32 bits into four groups, each of 8 bits • divided to a network portion and a host portion • Devices on the same LAN will have the same network portion but a unique host portion. To determine the network portion, a mask is used. nd eie507 03/04 15
  20. 20. LAN and WAN Technologies Network (subnet) mask • A network mask (32 bits) is used to determine the network portion • format: all 1’s followed by all 0’s • The network is always represented by a binary 1 in the subnet mask. Classical (classful) IP divides the address space into Class A, B, and C networks by dividing the 32-bit address on 8-bit (byte) boundaries. Classless IP divides, or subnets, these classic networks into smaller networks by breaking them on bit boundaries. • Subnetting: borrows bits from the host portion nd eie507 03/04 16
  21. 21. LAN and WAN Technologies Internetwork Packet Exchange/Sequenced Packet Exchange (IPX/SPX) protocol suite • Novell NetWare AppleTalk protocol • Apple Computer Inc. nd eie507 03/04 17
  22. 22. LAN and WAN Technologies Network Topology Overview • Ethernet • Ring nd eie507 03/04 18
  23. 23. LAN and WAN Technologies Basic Ethernet • developed in the late 70s at the Palo Alto Research Center (PARC) of Xerox • Variation: 10 Gigabit, Gigabit and Fast Ethernet • Ethernet is simply a group of devices that access a common shared medium, a cable, to exchange information. Operations: Carrier Sense Multiple Access and Collision Detection (CSMA/CD) – collisions deterorate throughput performance A broadcast network: collison domain and broadcast domain • Network equipment for an Ethernet network: hubs, bridges/switches, and routers. nd eie507 03/04 19
  24. 24. LAN and WAN Technologies Ethernet types • denoted as e.g., 10BaseT, Speed-Signaling-Media • Speed (the first part): the speed in Mbps • Signaling: the signaling type Base: baseband signaling • Media: the media type Media type: • T: unshielded twisted pair (UTP) cable The maximum transmission distance is 100 meters • F: fiber-optic cable. nd eie507 03/04 20
  25. 25. LAN and WAN Technologies The maximum transmission distance depends on the specific sub- type. e.g., for FB, the maximum transmission distance is 2000 meters. Hubs • Networking equipment, also known as repeaters since they just repeat what they receive • can be used to extend networks • may not have too many hubs • not suitable for large and complex networks Maximum 4 repeaters between source and destination (Ethernet) nd eie507 03/04 21
  26. 26. LAN and WAN Technologies Bridges/Switches • Networking equipment that operate at layer 2 of the OSI model • segment traffic based on layer-2 or MAC addresses • to isolate user traffic • To reduce the number of users in a collision domain Collision domain: the same shared media nd eie507 03/04 22
  27. 27. LAN and WAN Technologies • Bridges segment a network into several collision domains • The collision domains are still considered the same LAN • The use of more repeaters (for Ethernet) is made possible Routers • Segment broadcast domains (the whole LAN network) • Routers will never propagate a broadcast. nd eie507 03/04 23
  28. 28. LAN and WAN Technologies • A router is also the boundary of a LAN. • Connects two LANs or connects a LAN with a WAN • Operates at layer 3 of the OSI model • more complex and expensive • require more configuration Routers base their decisions on network and sub-network addresses. A subnet mask is used to extract the network address. For example (IP) nd eie507 03/04 24
  29. 29. LAN and WAN Technologies • host address AND subnet mask gi- ves net address • host address AND subnet mask gi- ves net address Routing protocols classification • distance vector • link state Distance Vector Link State RIP OSPF IGRP NLSP IPX RIP IS-IS nd eie507 03/04 25
  30. 30. LAN and WAN Technologies NLSP: the NetWare Link-Service Protocol, similar to OSPF and Intermediate System-to-Intermediate System (IS-IS), developed to overcome many of the issues associated with IPX RIP. Seven layer model and networking equipment Commonly used symbols nd eie507 03/04 26
  31. 31. LAN and WAN Technologies Ring Topology Stations are (logically) connected in a ring topology. Physically, stations are connected in a star topology. (Remarks: stations in an Ethernet are connected in a star topology.) Bridges, switches, and routers behave almost identically to their Ethernet counterparts. Fiber Distributed Data Interface (FDDI) • 100 Mbps • token-passing LAN technology • dual fiber-optic rings • often used as a high-speed backbone. nd eie507 03/04 27
  32. 32. Networking/internetworking Hardware and Software Networking/internetworking Hardware and Software
  33. 33. Networking/internetworking Hardware and Software Networking/internetworking Hardware and Software LAN to LAN/WAN Routers LAN Hubs, bridges, switches, (switch-routers) WAN to LAN Firewall, network address translation (NAT) Routers • small-office inexpensive, does not support FDDI and ATM Example: Cisco 2500 series (fixed LAN ports, 2 WAN interface cards (WICs)) • mid-range Example: Cisco 4000/3600 series nd eie507 03/04 28
  34. 34. Networking/internetworking Hardware and Software three modular slots for network processing modules (NPMs); (Each NPM holds one or more (Ethernet/ATM/DS3) ports.) A maximum of two high-speed interfaces • high-end routers Examples: 7000/7500 series and the Cisco 12000 Gigabit Switch Router (GSR) series used at the core of your network as a backbone router or the core of service provider and enterprise IP backbones LAN Switches • used to connect end users to the network • provide large quantities of ports nd eie507 03/04 29
  35. 35. Networking/internetworking Hardware and Software • Examples: Cisco 2900XL and 3500XL series, Cisco Catalyst 1900 switches Other Hardware • ISDN/DSL routers Example: Cisco 700 and 800 series • Remote Access Routers • Firewall Example: Cisco’s PIX • ATM switches nd eie507 03/04 30
  36. 36. Networking/internetworking Hardware and Software Software • Internetworking Operating System (IOS) Software Example: Cisco makes the routing decisions on a router • The Linux OS the route command (for static routing) zebra: a set of programs that implement various routing algorithms (e.g., RIP, OSPF) iptables: firewall and NAT nd eie507 03/04 31
  37. 37. Preliminaries in Network Design Preliminaries in Network Design Related issues • Networking technology used • Hardware Framework Triplet (Triangle) Media Protocols Transport • related to layers 2 and 3 of the OSI model • helps identify possible solutions Protocol problems nd eie507 03/04 32
  38. 38. Preliminaries in Network Design Media problems Transport problems Protocols problems Examples: • RIP cannot be used with Variable Length Subnet Masks (VLSMs) • NETBIOS cannot be routed Media • related to layer 2 • Example nd eie507 03/04 33
  39. 39. Preliminaries in Network Design 10 stations to a hub in a 10 Mpsb Ethernet, maximum 1 Mbps for each station 10 stations to switch in 10 Mbps Ethernet, maximum 10 Mbps for each station ∗ microsegmenting: each station resides in their own collision domain • Similarly in a token ring network: a layer 2 device can reduce the number of devices in a ring and hence reduce the waiting time. • Media problem example in a WAN: 100Kbps of traffic cannot be transmitted on a circuit of rate 64 Kbps nd eie507 03/04 34
  40. 40. Preliminaries in Network Design Transport • Specific types of traffic cannot be carried in a network • Example analog (native voice) signal cannot be carried on Ethernet • speed of the network: use a faster network • voice and data traffic over a WAN circuit ATM Multiprotocol label switching (MPLS) nd eie507 03/04 35
  41. 41. Preliminaries in Network Design Design Principles Example: Hierarchical Design - The Three-Layer Approach Three layers • the core layer provides the backbone transport services • the distribution layer provides policybased connectivity • the access layer provides end-user access to the network nd eie507 03/04 36
  42. 42. Preliminaries in Network Design Advantages • Easier to understand • Easier to troubleshoot • Easier to grow The Core Layer • the backbone of the network • provides reliable, high-speed communications to all distribution layers of the network • can encompass both WAN and LAN technologies nd eie507 03/04 37
  43. 43. Preliminaries in Network Design • High reliability: crucial • Redundancy and fault tolerance • Adaptability • Limited size or diameter • Low latency and fast processing • Manageability The Distribution Layer • the interface between the core and the access layers • policy-based connectivity nd eie507 03/04 38
  44. 44. Preliminaries in Network Design • implemented in routers and switches • Route redistribution and address summarization: various routing protocols • Media translations • Network Address Translation (NAT) • QoS • Access-list filtering: restrict any unwanted traffic • Encryption: not in the core layer since it will introduces latency not in the access layer (it would imply multiple encryption processes.) nd eie507 03/04 39
  45. 45. The Access Layer • provides network access for all end stations • generally implemented with hubs and switches • raw network connectivity Summary • Two design fundamentals the framework triangle the three-layer hierarchy • Fundamentals of technology and equipment nd eie507 03/04 40