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Intern

  1. 1. Networking Arjun Rahul Sheeba Tushar ONGC July 6, 2012
  2. 2. Outline Introduction ONGC Our Experience Network Devices Modems FDDI 802.3 - Ethernet Networks Topology Network Interface Cards Types of Network IP Addressing DNS 2 of 83
  3. 3. Acknowledgement We like to thank Mrs Chaddha for her guidance throughout our internship. 3 of 83
  4. 4. ONGC Oil and Natural Gas Corporation Limited (ONGC) is an Indian state-owned oil and gas company headquartered in Dehradun, India. It is one of the largest Asia-based oil and gas exploration and production companies, and produces around 77% of India’s crude oil (equivalent to around 30% of the country’s total demand) and around 81% of its natural gas. ONGC is one of the largest publicly traded companies by market capitalization in India. It is ranked 361st in the 2011 Fortune Global 500 list and is among the Top 250 Global Energy Company by Platts. 4 of 83
  5. 5. Our Experience (1) Through our intership at ONGC we were exposed to the inner working of the server room at Telbhawan. We examined the working of the following servers • AD - Active Director, used for authentication of employees of the ONGC by verifying theirs CPF numbers. • DHCP - Dynamic Host Control Protocol, used to allocated dynamic IP address. • Anti-virus - It is used for verifying if the client has anti-virus installed in it. • IWSS - It is used for scanning the computers in the network • Blue Coat - It is the Internet distribution proxy 5 of 83
  6. 6. Our Experience (2) • WSUS - Windows System Update Server, used to update the software of all the computers in the network. • Websense - It filters the computers for possible threat The ISP provider to ONGC is BSNL. Four lease lines of 2 Kbps is connecting Delhi to Dehradun. The main router used in ONGC is IAS from Cisco. At Dehradun, various routers & switch of Cisco are used. The intranet of ONGC at Telbhawan is connected to KDMIP though L3 switches. The optical fiber is extended to City Hospital. We then visited KDMIP which uses SATCOM for communication. The satellite works in the Ka Band channel with 3 GHz. 6 of 83
  7. 7. Modem (1) A modem (modulator-demodulator) is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data. The most familiar example is a voice band modem that turns the digital data of a personal computer into modulated electrical signals in the voice frequency range of a telephone channel. These signals can be transmitted over telephone lines and demodulated by another modem at the receiver side to recover the digital data. 7 of 83
  8. 8. Modem (2) Figure: Modem Modems are generally classified by the amount of data they can send in a given unit of time, usually expressed in bits per second (bit/s, or bps). Modems can alternatively be classified by their symbol rate, measured in baud. The baud unit denotes symbols per second, or the number of times per second the modem sends a new signal. Modems are of two types : 8 of 83
  9. 9. Modem (3) Figure: Internal Modem Figure: External Modem 9 of 83
  10. 10. Fiber Distributed Data Interface (1) The Fiber Distributed Data Interface (FDDI) topology is ring with two counter rotating rings for reliability with no hubs. Cable type is fiber-optic. Connectors are specialized. The media access method is token passing. The maximum length is 100 kilometers. The maximum number of nodes on the network is 500. Speed is 100 Mbps. FDDI is normally used as a backbone to link other networks. A typical FDDI network can include servers, concentrators, and links to other networks. Devices called concentrators provide functions similar to hubs. Most concentrators use dual attachment station network cards but single attachment concentrators may be used to attach more workstations to the network. 10 of 83
  11. 11. Fiber Distributed Data Interface (2) Figure: FDDI 11 of 83
  12. 12. Fiber Distributed Data Interface (3) FDDI token passing allows multiple frames to circulate around the ring at the same time. Priority levels of a data frame and token can be set to allow servers to send more data frames. Time sensitive data may also be given higher priority. The second ring in a FDDI network is a method of adjusting when there are breaks in the cable. The primary ring is normally used, but if the nearest downstream neighbor stops responding the data is sent on the secondary ring in attempt to reach the computer. Therefore a break in the cable will result in the secondary ring being used. 12 of 83
  13. 13. Fiber Distributed Data Interface (4) Figure: FDDI 13 of 83
  14. 14. Fiber Distributed Data Interface (5) There are two network cards which are: • Dual attachment stations (DAS) used for servers and concentrators are attached to both rings. • Single Attachment stations (SAS) attached to one ring and used to attach workstations to concentrators. A router or switch can link an FDDI network to a local area network (LAN). Normally FDDI is used to link LANs together since it covers long distances. 14 of 83
  15. 15. Ethernet (1) In 1973, at Xerox Corporations Palo Alto Research Center (more commonly known as PARC), researcher Bob Metcalfe designed and tested the first Ethernet network. While working on a way to link Xeroxs ”Alto” computer to a printer, Metcalfe developed the physical method of cabling that connected devices on the Ethernet as well as the standards that governed communication on the cable. Ethernet has since become the most popular and most widely deployed network technology in the world. Many of the issues involved with Ethernet are common to many network technologies, and understanding how Ethernet addressed these issues can provide a foundation that will improve your understanding of networking in general. 15 of 83
  16. 16. Ethernet (2) The Ethernet standard has grown to encompass new technologies as computer networking has matured, but the mechanics of operation for every Ethernet network today stem from Metcalfes original design. The original Ethernet described communication over a single cable shared by all devices on the network. Once a device attached to this cable, it had the ability to communicate with any other attached device. This allows the network to expand to accommodate new devices without requiring any modification to those devices already on the network. 16 of 83
  17. 17. 17 of 83
  18. 18. Ethernet Cabling (1) Figure: Ethernet Cabling 18 of 83
  19. 19. Ethernet Cabling (2) Figure: The most common kinds of Ethernet cabling 19 of 83
  20. 20. Network Topologies • Topology - Physical and logical network layout ◦ Physical actual layout of the computer cables and other network devices ◦ Logical the way in which the network appears to the devices that use it. • Common topologies ◦ Bus, ring, star, mesh and wireless 20 of 83
  21. 21. Bus Topology • Uses a trunk or backbone to which all of the computers on the network connect. • Uses a trunk or backbone to which all of the computers on the network connect. • Coaxial cablings ( 10Base-2, 10Base5) were popular options years ago. 21 of 83
  22. 22. Advantages • Cable faults are easily located, making troubleshooting easier • Ring network are moderately easy to install Disadvantages • Expansion to the network can cause network disruption • A single break in the cable can disrupt the entire network Figure: Bus Topology 22 of 83
  23. 23. Star Topology • All computers/devices connect to a central device called hub or switch. • Each device requires a single cable • point-to-point connection between the device and hub. • Most widely implemented • Hub is the single point of failure 23 of 83
  24. 24. Figure: Star Topology 24 of 83
  25. 25. Advantages • Easily expanded without disruption to the network • Cable failure affects only a single user • Easy to troubleshoot & isolate problems Disadvantages • Requires more cable • A central connecting device allows for a single point of failure • More difficult to implement 25 of 83
  26. 26. Mesh Topology • Each computer connects to every other • High level of redundancy. • Rarely used ◦ Wiring is very complicated ◦ Cabling cost is high ◦ Troubleshooting a failed cable is tricky ◦ A variation hybrid mesh create point to point connection between specific network devices, often seen in WAN implementation. 26 of 83
  27. 27. Advantages • Provides redundant path between devices • The network can be expanded without to current uses Disadvantages • Requires more cable than the other LAN topologies • Complicated Figure: Mesh Topology 27 of 83
  28. 28. Wireless • Do not require physical cabling • Particularly useful for remote access for laptop users • Eliminate cable faults and cable breaks. • Signal interference and security issue. 28 of 83
  29. 29. Advantages • Allows for wireless remote access • Network can be expanded without disruption to current users Disadvantages • Potential security issues associated with wireless transmission • Limited speed in comparison to other network topologies Figure: Wireless 29 of 83
  30. 30. NIC • A network interface card, more commonly referred to as a NIC, is a device that allows computers to be joined together in a LAN, or local area network . • The network interface card acts as the liaison for the machine to both send and receive data on the LAN . • In computer networking, a NIC provides the hardware interface between a computer and a network. 30 of 83
  31. 31. Figure: Network cards are typically available in 10/100/1000 Mbit/s varieties. This means they can support a notional maximum transfer rate of 10, 100 or 1000 Megabits per second 31 of 83
  32. 32. NIC ...Need • Most computer networks transfer data across a medium at a fixed rate, often faster than the speed at which computers can process individual bits. • To accommodate the mismatch in speed, each computer attached to a network contain special purpose hardware known as a network interface card (NIC). • The NIC functions like an I/O device: it is built for a specific network technology. • It handles the details of frame transmission or reception without requiring the CPU to process each bit. 32 of 83
  33. 33. NIC (1) ...Working • A computer or device on a network can be reached by its MAC (media access control) address through the NIC card. • Every Ethernet network card has a unique 48-bit serial number called a MAC address, which is stored in ROM carried on the card. • The MACs on the network are used to direct traffic between the computers. • An example of a MAC address: A1B2C3D4E5F6 • The first 6 hex digits in the MAC address is the OUI (organizationally unique identifier), assigned by the IEEE to each manufacturer (e.g. Cisco, Intel etc). 33 of 83
  34. 34. NIC (2) ...Working • The rest of the MAC address can be assigned in any way by the manufacturer to the individual networking devices that it manufactures 34 of 83
  35. 35. NIC ...Port • The back plate of the network interface card features a port that looks similar to a phone jack, but is slightly larger. • A network card typically has a twisted pair, BNC, or AUI socket where the network cable is connected, and a few LEDs to inform the user of whether the network is active, and whether or not there is data being transmitted on it. • That port accommodates an Ethernet cable, which resembles a thicker version of a standard telephone line. 35 of 83
  36. 36. 36 of 83
  37. 37. Figure: Network Interface Card for connection of a computer to an Ethernet Network 37 of 83
  38. 38. NIC ...on a Network • The card implements the electronic circuitry required to communicate using a specific physical layer and data link layer standard such as Ethernet or token ring. • This provides a base for a full network protocol stack, allowing communication among small groups of computers on the same LAN and large-scale network communications through routable protocols, such as IP. 38 of 83
  39. 39. Types of Network • Local Area Network • Wide Area Netwok • Metropolitan Area Network • Wireless Networks • Home Networks • Internetworks 39 of 83
  40. 40. 40 of 83
  41. 41. LAN A LAN connects network devices over a relatively short distance. A networked office building, school, or home usually contains a single LAN, though sometimes one building will contain a few small LANs (perhaps one per room), and occasionally a LAN will span a group of nearby buildings. In TCP/IP networking, a LAN is often but not always implemented as a single IP subnet. 41 of 83
  42. 42. Figure: An isolated IAN connecting 12 computers to a hub in a closet 42 of 83
  43. 43. WAN As the term implies, a WAN spans a large physical distance. The Internet is the largest WAN, spanning the Earth. A WAN is a geographically-dispersed collection of LANs. A network device called a router connects LANs to a WAN. In IP networking, the router maintains both a LAN address and a WAN address. 43 of 83
  44. 44. 44 of 83
  45. 45. Wireless (1) Wireless network refers to any type of computer network that is not connected by cables of any kind. It is a method by which homes, telecommunications networks and enterprise (business) installations avoid the costly process of introducing cables into a building, or as a connection between various equipment locations. Wireless telecommunications networks are generally implemented and administered using a transmission system called radio waves. This implementation takes place at the physical level (layer) of the OSI model network structure. 45 of 83
  46. 46. Wireless (2) Figure: Wireless 46 of 83
  47. 47. Types of wireless networks (1) • Wireless PAN ◦ Wireless personal area networks (WPANs) interconnect devices within a relatively small area that is generally within a person’s reach. For example, both Bluetooth radio and invisible infrared light provides a WPAN for interconnecting a headset to a laptop. Wi-Fi PANs are becoming commonplace as equipment designers start to integrate Wi-Fi into a variety of consumer electronic devices. 47 of 83
  48. 48. Types of wireless networks (2) • Wireless LANs ◦ A wireless local area network (WLAN) links two or more devices over a short distance using a wireless distribution method, usually providing a connection through an access point for Internet access. The use of spread-spectrum or OFDM technologies may allow users to move around within a local coverage area, and still remain connected to the network. Products using the IEEE 802.11 WLAN standards are marketed under the Wi-Fi brand name. Fixed wireless technology implements point-to-point links between computers or networks at two distant locations, often using dedicated microwave or modulated laser light beams over line of sight paths. It is often used in cities to connect networks in two or more buildings without installing a wired link. 48 of 83
  49. 49. Types of wireless networks (3) • Wireless mesh network ◦ A wireless mesh network is a wireless network made up of radio nodes organized in a mesh topology. Each node forwards messages on behalf of the other nodes. Mesh networks can ”self heal”, automatically re-routing around a node that has lost power. • Wireless MAN ◦ Wireless metropolitan area networks are a type of wireless network that connects several wireless LANs. WiMAX is a type of Wireless MAN and is described by the IEEE 802.16 standard. 49 of 83
  50. 50. Types of wireless networks (4) • Wireless WAN ◦ Wireless wide area networks are wireless networks that typically cover large areas, such as between neighboring towns and cities, or city and suburb. These networks can be used to connect branch offices of business or as a public internet access system. The wireless connections between access points are usually point to point microwave links using parabolic dishes on the 2.4GHz band, rather than omnidirectional antennas used with smaller networks. A typical system contains base station gateways, access points and wireless bridging relays 50 of 83
  51. 51. Other Types of Area Networks (1) • Metropolitan Area Network - a network spanning a physical area larger than a LAN but smaller than a WAN, such as a city. A MAN is typically owned an operated by a single entity such as a government body or large corporation. • Campus Area Network - a network spanning multiple LANs but smaller than a MAN, such as on a university or local business campus. • Storage Area Network - connects servers to data storage devices through a technology like Fibre Channel. • System Area Network - links high-performance computers with high-speed connections in a cluster configuration. Also known as Cluster Area Network. 51 of 83
  52. 52. OSI Model Virtually all networks in use today are based in some fashion on the Open Systems Interconnection (OSI) standard. OSI was developed in 1984 by the International Organization for Standardization (ISO), a global federation of national standards organizations representing approximately 130 countries. 52 of 83
  53. 53. 53 of 83
  54. 54. The Layers Think of the seven layers as the assembly line in the computer. At each layer, certain things happen to the data that prepare it for the next layer. 54 of 83
  55. 55. Application Set • Application - This is the layer that actually interacts with the operating system or application whenever the user chooses to transfer files, read messages or perform other network-related activities. • Presentation - Layer 6 takes the data provided by the Application layer and converts it into a standard format that the other layers can understand. • Session - Layer 5 establishes, maintains and ends communication with the receiving device. 55 of 83
  56. 56. Transport Set (1) • Transport - This layer maintains flow control of data and provides for error checking and recovery of data between the devices. Flow control means that the Transport layer looks to see if data is coming from more than one application and integrates each application’s data into a single stream for the physical network. • Network - The way that the data will be sent to the recipient device is determined in this layer. Logical protocols, routing and addressing are handled here. • Data - In this layer, the appropriate physical protocol is assigned to the data. Also, the type of network and the packet sequencing is defined. 56 of 83
  57. 57. Transport Set (2) • Physical - This is the level of the actual hardware. It defines the physical characteristics of the network such as connections, voltage levels and timing. 57 of 83
  58. 58. Benefits of the OSI Model By separating the network communications into logical smaller pieces, the OSI model simplifies how network protocols are designed. The OSI model was designed to ensure different types of equipment (such as network adapters, hubs, and routers) would all be compatible even if built by different manufacturers. A product from one network equipment vendor that implements OSI Layer 2 functionality, for example, will be much more likely to interoperate with another vendor’s OSI Layer 3 product because both vendors are following the same model. 58 of 83
  59. 59. IPv4 Addressing An IP address is an identifier that is assigned at the Internet layer to an interface or a set of interfaces. Each IP address can identify the source or destination of IP packets. For IPv4, every node on a network has one or more interfaces, and you can enable TCP/IP on each of those interfaces. When you enable TCP/IP on an interface, you assign it one or more logical IPv4 addresses, either automatically or manually. The IPv4 address is a logical address because it is assigned at the Internet layer and has no relation to the addresses that are used at the Network Interface layer. IPv4 addresses are 32 bits long 59 of 83
  60. 60. Figure: IPv4 Address Syntax 60 of 83
  61. 61. Types of IPv4 Addresses Internet standards define the following types of IPv4 addresses: • Unicast Assigned to a single network interface located on a specific subnet; used for one-to-one communication. • Multicast Assigned to one or more network interfaces located on various subnets; used for one-to-many communication • Broadcast Assigned to all network interfaces located on a subnet; used for one-to-everyone on a subnet communication. 61 of 83
  62. 62. Public address • Most IP addresses are public addresses. Public addresses are registered as belonging to a specific organization. • Internet Service Providers (ISP) and extremely large organizations in the U.S. obtain blocks of public addresses from the American Registry for Internet Numbers (ARIN http://www.arin.net). Other organizations obtain public addresses from their ISPs. • There are ARIN counterparts in other parts of the world, and all of these regional registration authorities are subject to the global Internet Assigned Numbers Authority (IANA http://www.iana.org). • Public IP addresses are routed across the Internet, so that hosts with public addresses may freely communicate with one another globally. 62 of 83
  63. 63. Private Address • RFC 1918 designates the following as private addresses. ◦ Class A range: 10.0.0.0 through 10.255.255.255. ◦ Class B range: 172.16.0.0 through 172.31.255.255. ◦ Class C range: 192.168.0.0 through 192.168.255.255. • Private addresses may be used by any organization, without any requirement for registration. • Because private addresses are ambiguous - cant tell where theyre coming from or going to because anyone can use them - private addresses are not permitted to be routed across the Internet • ISPs block private addresses from being routed across their infrastructure. 63 of 83
  64. 64. Classful IP Addressing (1) Three main classes • Class A networks ◦ First octet values range from 1 through 126. ◦ First octet starts with bit 0 ◦ Network mask is 8 bits, written /8 or 255.0.0.0. ◦ 1.0.0.0 through 126.0.0.0 are class A networks with 16777214 hosts each. • Class B networks ◦ First octet values range from 128 through 191. ◦ First octet starts with binary pattern 10. ◦ Network mask is 16 bits, written /16 or 255.255.0.0. ◦ 128.0.0.0 through 191.255.0.0 are class B networks, with 65534 hosts each. 64 of 83
  65. 65. Classful IP Addressing (2) • Class C networks ◦ First octet values range from 192 through 223. ◦ First octet starts with binary pattern 110. ◦ Network mask is 24 bits, written /24 or 255.255.255.0. ◦ 192.0.0.0 through 223.255.255.0 are class C networks, with 254 hosts each 65 of 83
  66. 66. Two additional classes and reserved addresses • Class D addresses ◦ First octet values range from 224 through 239. ◦ First octet starts with binary pattern 1110. ◦ Class D addresses are multicast addresses, which will not be discussed in this tutorial. • Class E addresses ◦ Essentially everything thats left. ◦ Experimental class, which will not be discussed in this tutorial. • Reserved addresses ◦ 0.0.0.0 is the default IP address, and it is used to specify a default route. The default route will be discussed later. ◦ Addresses beginning with 127 are reserved for internal loopback addresses. It is common to see 127.0.0.1 used as the internal loopback address on many devices. 66 of 83
  67. 67. Subnet Masks (1) Extending the classful network mask • Subnet masks are used to make classful networks more manageable and efficient, by creating smaller subnets and reducing the number of host addresses per subnet to what is actually required. • Subnet masks were first used on class boundaries. • Example ◦ Take class A network 10.0.0.0 with network mask 255.0.0.0. ◦ Add additional 8 subnet bits to network mask. ◦ New subnet mask is 255.255.0.0. ◦ New subnets are 10.0.0.0, 10.1.0.0, 10.2.0.0, and so on with 65534 host addresses per subnet. Still too many hosts per subnet. • Example ◦ Take class A network 10.0.0.0 with network mask 255.0.0.0. 67 of 83
  68. 68. Subnet Masks (2) ◦ Add additional 16 subnet bits to network mask. ◦ New subnet mask is 255.255.255.0 ◦ New subnets are 10.0.0.0, 10.0.1.0, 10.0.2.0, ..., 10.1.0.0, 10.1.1.0, 10.1.2.0, ..., 10.2.0.0, 10.2.1.0, 10.2.2.0, and so on with 254 host addresses per subnet. • Example ◦ Take class B network 172.16.0.0 with network mask 255.255.0.0. ◦ Add additional 8 subnet bits to network mask. ◦ New subnet mask is 255.255.255.0 ◦ New subnets are 172.16.0.0, 172.16.1.0, 172.16.2.0, and so on with 254 host addresses per subnet. • As shown in these examples... ◦ A class A network can be subnetted to create 256 (28 ) /16 subnets. ◦ A class A network can be subnetted to create 65536 (216 ) /24 subnets. ◦ A class Bnetwork can be subnetted to create 256 (28 ) /24 subnets. 68 of 83
  69. 69. DNS Short for Domain Name System (or Service or Server), an Internet service that translates domain names into IP addresses. Because domain names are alphabetic, they’re easier to remember. The Internet however, is really based on IP addresses. Every time you use a domain name, therefore, a DNS service must translate the name into the corresponding IP address. For example, the domain name www.example.com might translate to 198.105.232.4. 69 of 83
  70. 70. Figure: DNS 70 of 83
  71. 71. Figure: The DNS client program sends a request to a DNS server to map the e-mail address to the corresponding IP address 71 of 83
  72. 72. Namespace (1) A name space that maps each address to a unique name can be organized in two ways: flat or hierarchical. Flat Name Space In a flat name space, a name is assigned to an address. A name in this space is a sequence of characters without structure. The main disadvantage of a fiat name space is that it cannot be used in a large system such as the Internet because it must be centrally controlled to avoid ambiguity and duplication. Hierarchical Name Space In a hierarchical name space, each name is made of several parts. The first part can define the nature of the organization, the second 72 of 83
  73. 73. Namespace (2) part can define the name of an organization, the third part can define departments in the organization, and so on. For example, assume two colleges and a company call one of their computers challenger. The first college is given a name by the central authority such as jhda.edu, the second college is given the name berkeley.edu, and the company is given the name smart. com. When these organizations add the name challenger to the name they have already been given, the end result is three distinguishable names: challenger.jhda.edu, challenger.berkeley.edu, and challenger.smart.com. The names are unique without the need for assignment by a central authority. 73 of 83
  74. 74. Figure: The domain names are always read from the node up to the root 74 of 83
  75. 75. Figure: The last label is the label of the root (null) as below 75 of 83
  76. 76. Domain Figure: A domain is a subtree of the domain name space. The name of the domain is the domain name of the node at the top of the subtree 76 of 83
  77. 77. DISTRIBUTION OF NAME SPACE Hierarchy of Name Servers The solution to these problems is to distribute the information among many computers called DNS servers. One way to do this is to divide the whole space into many domains based on the first level. 77 of 83
  78. 78. Zone Since the complete domain name hierarchy cannot be stored on a single server, it is divided among many servers. What a server is responsible for or has authority over is called a zone. The server makes a database called a zone file and keeps all the information for every node under that domain. 78 of 83
  79. 79. Root Server A root server is a server whose zone consists of the whole tree. There are several root servers, each covering the whole domain name space. Primary and Secondary Servers A primary server loads all information from the disk file; the secondary server loads all information from the primary server. When the secondary downloads information from the primary, it is called zone transfer. 79 of 83
  80. 80. Figure: DNS is a protocol that can be used in different platforms. In the Internet, the domain name space (tree) is divided into three different sections: generic domains, country domains, and the inverse domain 80 of 83
  81. 81. Generic Domains Figure: The generic domains define registered hosts according to their generic behavior. Each node in the tree defines a domain, which is an index to the domain name space database 81 of 83
  82. 82. Country Domains Figure: The country domains section uses two-character country abbreviations (e.g., us for United States). Second labels can be organizational, or they can be more specific, national designations. 82 of 83
  83. 83. Inverse Domain The inverse domain is used to map an address to a name. This may happen, for example, when a server has received a request from a client to do a task. Although the server has a file that contains a list of authorized clients, only the IP address of the client (extracted from the received IP packet) is listed. The server asks its resolver to send a query to the DNS server to map an address to a name to determine if the client is on the authorized list. 83 of 83

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