Chapter Overview

1
Chapter Overview

• IP
• IPX
• NetBEUI
• AppleTalk

2
Network Layer Protocols

• Responsible for end-to-end communications on an
  internetwork
• Contrast with data-link layer protocols, which
  provide communications on the same local area
  network (LAN)

3
IP Encapsulation
4
IP Functions

• Encapsulation
• Addressing
• Routing
• Fragmentation
• Protocol identification

5
The IP Datagram Format
6
IP Addresses

• Internet Protocol (IP) is the only network layer
  protocol with its own addressing system.
• IP addresses are 32 bits long.
• IP addresses have two parts a network identifier
  and a host identifier.
• IP addresses are assigned to network interface
  adapters, not to computers.
• The Source IP Address field in the IP header
  always identifies the computer that generated the
  packet.
• The Destination IP Address field in the IP header
  always identifies the packets final destination.

7
End Systems and Intermediate Systems
8
Fragmentation

• Routers connect networks that support
  different-sized packets.
• The largest packet size supported by a network is
  called its maximum transmission unit (MTU).
• When a packet is too large to be forwarded to a
  particular network, the router splits it into
  fragments.
• Each fragment is encapsulated with a header and
  is transmitted as a separate packet.
• Fragments are not reassembled until they reach
  their final destination.
• Fragments can themselves be fragmented.

9
Fragmentation (Cont.)
10
Protocol Field Values
0 IP
1 ICMP
3 Gateway-to-Gateway Protocol (GGP)
6 TCP
8 Exterior Gateway Protocol (EGP)
17 UDP
11
The IPX Standard

• Developed by Novell for use with NetWare
• Proprietary never published as a public standard
• Reverse engineered by Microsoft to create NWLink

12
IPX Functions

• Routing
• Addressing
• Protocol identification

13
The IPX Header Format
14
IPX Addressing

• Internet Packet Exchange (IPX) uses
• Separate node and network addresses
• Network interface adapter hardware addresses for
  node addresses
• Network addresses
• Are assigned by administrators
• Do not need to be registered

15
NetBEUI Characteristics

• Original Microsoft Windows default networking
  protocol
• Designed for small local area networks (LANs)
• Does not support Internet communications
• Does not need configuration
• Can be used to troubleshoot Transmission Control
  Protocol/Internet Protocol (TCP/IP) configuration
  protocols

16
NetBIOS Names

• Assigned to computers during Windows installation
• Sixteen characters long the sixteenth character
  is a resource identifier
• Can identify computers, domain controllers,
  users, groups, and other resources
• Have no network identifier (which is why NetBEUI
  is nonroutable)

17
The NBF Protocol Format
18
Protocols Using NBF

• Name Management Protocol (NMP)
• Session Management Protocol (SMP)
• User Datagram Protocol (UDP)
• Diagnostic and Monitoring Protocol (DMP)

19
AppleTalk Data-Link Layer Options

• LocalTalk
• EtherTalk
• Fast EtherTalk
• TokenTalk
• FDDITalk

20
Datagram Delivery Protocol

• AppleTalks network layer protocol
• Provides packet addressing, routing, and protocol
  identification
• Has short-format and long-format packet headers

21
AppleTalk Addressing

• AppleTalk computers have a unique 8-bit node ID
  that is self-assigned.
• AppleTalk networks can have no more than 254
  nodes.
• AppleTalk uses 16-bit network numbers for
  routing.
• Computers obtain network numbers using the Zone
  Information Protocol (ZIP).
• Computer processes are identified by 8-bit socket
  numbers.

22
AppleTalk Addressing (Cont.)

• Network numbers, node IDs, and socket numbers are
  expressed as three decimal numbers, separated by
  periods.
• AppleTalk computers resolve node IDs into
  hardware addresses, using the AppleTalk Address
  Resolution Protocol (AARP).
• AppleTalk computers also have friendly names and
  groups of computers called zones.

23
Chapter Summary

• Network layer protocols are responsible for
  end-to-end communications across the network.
• IP is a connectionless protocol that encapsulates
  transport layer data into datagrams.
• IPX is a proprietary standard that performs
  routing, addressing, and protocol identification.
• NetBIOS Extended User Interface (NetBEUI) is used
  by small Windows networks for LAN networking.
• AppleTalk provides basic networking to small
  networks.