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ECE 4110 – Internetwork Programming

ECE 4110 – Internetwork Programming. TCP/IP Protocol (cont’d). Preamble: Alternating 0’s and 1’s with last bit a l. Destination medium access control (MAC) address: Each receiver DL layer compares this to its own hardwired network interface card (NIC) address.

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ECE 4110 – Internetwork Programming

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  1. ECE 4110 – Internetwork Programming TCP/IP Protocol (cont’d)

  2. Preamble: Alternating 0’s and 1’s with last bit a l. Destination medium access control (MAC) address: Each receiver DL layer compares this to its own hardwired network interface card (NIC) address. Normally a NIC knows its own address and the broadcast address. Source MAC address: Sender’s NIC address. Type: Type of data transporting. E.g.: Internet Protocol. Cyclic Redundancy Check: Used for checking data integrity. Gap: After the Ethernet Frame, a 12 Byte Interframe Gap must always follow. Note: Receiver DL layer does not look at data. Note:Data is in most network technologies called a “packet.” Preamble (8 Bytes) Destination MAC Address (6 Bytes) Source MAC Address (6 Bytes) Type (2 Bytes) Data CRC (4 Bytes) Gap 12 Bytes DIX Ethernet Data Frame Format ECE 4110 – Internetwork Programming

  3. Network Number (Address) 1 Router Network Routing Concepts B C 3 Computer X Computer Y 4 2 9 A1 A2 A4 1 5 A A3 D 6 8 E 7 Computer X on Network wants to send a message to Computer Y on Network . F 1 5 ECE 4110 – Internetwork Programming

  4. Destination MAC Address Source MAC address IEEE 802.3 Frame DATA Preamble Length CRC Destination 5 : Y Source 1 : X Other Stuff Data Routing Concepts (cont’d) • Network address is software configurable. ECE 4110 – Internetwork Programming

  5. Routing • Service • Connection-oriented • Connectionless • Delivery • Direct Delivery • Indirect delivery ECE 4110 – Internetwork Programming

  6. Connection-Oriented vs. Connectionless • In connection-oriented services, the network layer protocol first makes a connection. • In connectionless services, each packet is treated independently. So, there is no relationship between the packets. ECE 4110 – Internetwork Programming

  7. Direct Delivery • Source and the destination are on the same physical network. • Address mapping is between IP and physical address of the final destination. • Physical address of the destination is found via ARP. * From TCP/IP Protocol Suite, B. A. Forouzan, Prentice Hall ECE 4110 – Internetwork Programming

  8. Indirect Delivery • Source and destination are on different networks. • Address mapping is between IP and physical address of the next hop. * From TCP/IP Protocol Suite, B. A. Forouzan, Prentice Hall ECE 4110 – Internetwork Programming

  9. Routing Methods • Next-hop routing • Network-specific routing • Host-specific routing • Default routing ECE 4110 – Internetwork Programming

  10. Next-Hop Routing * From TCP/IP Protocol Suite, B. A. Forouzan, Prentice Hall ECE 4110 – Internetwork Programming

  11. Network-Specific Routing * From TCP/IP Protocol Suite, B. A. Forouzan, Prentice Hall ECE 4110 – Internetwork Programming

  12. Host-Specific Routing * From TCP/IP Protocol Suite, B. A. Forouzan, Prentice Hall ECE 4110 – Internetwork Programming

  13. Default Routing * From TCP/IP Protocol Suite, B. A. Forouzan, Prentice Hall ECE 4110 – Internetwork Programming

  14. Static vs. Dynamic Routing • In static routing, routing table is constructed manually. • In dynamic routing, routing table is constructed automatically using protocols like RIP, OSPF, or BGP. ECE 4110 – Internetwork Programming

  15. Routing Table • Flags • U The router is up and running. • G The destination is a gateway (indirect delivery). • H Host-specific address. • D Added by redirection (by ICMP). • M Modified by redirection (by ICMP). ECE 4110 – Internetwork Programming

  16. Routing Module * From TCP/IP Protocol Suite, B. A. Forouzan, Prentice Hall ECE 4110 – Internetwork Programming

  17. Routing Module (cont’d) • Search for route in this order: • Direct delivery • Host-specific delivery • Network-specific delivery • Default delivery ECE 4110 – Internetwork Programming

  18. Routing Module (algorithm) • For each entry in RT: • Apply the mask to destination address • If result of mask matches the destination field in the entry in RT, find next-hop address as follows: • If G flag is set • Use next-hop field in RT • Else • Use destination address in the packet (direct delivery) • Send packet to fragmentation module with the next-hop address • Stop • Else, send ICMP error message • Stop ECE 4110 – Internetwork Programming

  19. Example Topology * From TCP/IP Protocol Suite, B. A. Forouzan, Prentice Hall

  20. MaskDestination Next HopInterface 255.0.0.0 111.0.0.0 - m0 255.255.255.224 193.14.5.160 - m2 255.255.255.224 193.14.5.192 - m1 255.255.255.255 194.17.21.16 111.20.18.14 m0 255.255.255.0 192.16.7.0 111.15.17.32 m0 255.255.255.0 194.17.21.0 111.20.18.14 m0 0.0.0.0 0.0.0.0 111.30.31.18 m0 Routing Table for R1 ECE 4110 – Internetwork Programming

  21. Example 1 • Router R1 receives 500 packets for destination 192.16.7.14; the algorithm applies the masks row by row to the destination address until a match (with the value in the second column) is found. ECE 4110 – Internetwork Programming

  22. Example 1 (Solution) • Direct delivery 192.16.7.14 & 255.0.0.0  192.0.0.0 no match 192.16.7.14 & 255.255.255.224  192.16.7.0 no match 192.16.7.14 & 255.255.255.224  192.16.7.0 no match • Host-specific 192.16.7.14 & 255.255.255.255  192.16.7.14 no match • Network-specific 192.16.7.14 & 255.255.255.0  192.16.7.0 match ECE 4110 – Internetwork Programming

  23. Example 2 • Router R1 receives 100 packets for destination 193.14.5.176; the algorithm applies the masks row by row to the destination address until a match is found. ECE 4110 – Internetwork Programming

  24. Example 2 (Solution) • Direct delivery 193.14.5.176 & 255.0.0.0  193.0.0.0 no match 193.14.5.176 & 255.255.255.224  193.14.5.160 match ECE 4110 – Internetwork Programming

  25. Example 3 • Router R1 receives 20 packets for destination 200.34.12.34; the algorithm applies the masks row by row to the destination address until a match is found. ECE 4110 – Internetwork Programming

  26. Example 3 (Solution) • Direct delivery 200.34.12.34 & 255.0.0.0  200.0.0.0 no match 200.34.12.34 & 255.255.255.224  200.34.12.32 no match 200.34.12.34 & 255.255.255.224  200.34.12.32 no match • Host-specific 200.34.12.34 & 255.255.255.255  200.34.12.34 no match • Network-specific 200.34.12.34 & 255.255.255.0  200.34.12.0 no match 200.34.12.34 & 255.255.255.0  200.34.12.0 no match • Default 200.34.12.34 & 0.0.0.0  0.0.0.0 match ECE 4110 – Internetwork Programming

  27. Example 4 • Make the routing table for router R1 ECE 4110 – Internetwork Programming

  28. Example 4 (Solution) MaskDestinationNext HopInterface 255.255.0.0 134.18.0.0 - m0 255.255.0.0 129.8.0.0 222.13.16.40 m1 255.255.255.0 220.3.6.0 222.13.16.40 m1 0.0.0.0 0.0.0.0 134.18.5.2 m0 ECE 4110 – Internetwork Programming

  29. Example 5 • Make the routing table for router R1 ECE 4110 – Internetwork Programming

  30. Example 5 (Solution) MaskDestinationNext HopInterface 255.255.255.0 200.8.4.0 - m2 255.255.255.0 80.4.5.0 201.4.10.3 m1 or 200.8.4.12 or m2 255.255.255.0 80.4.6.0 201.4.10.3 m1 or 200.4.8.12 or m2 0.0.0.0 0.0.0.0 ???????????? m0 ECE 4110 – Internetwork Programming

  31. Example 6 • Given the routing table in the next slide, draw the topology. ECE 4110 – Internetwork Programming

  32. Example 6 (cont’d) MaskDestinationNext HopInterface 255.255.0.0 110.70.0.0 - m0 255.255.0.0 180.14.0.0 - m2 255.255.0.0 190.17.0.0 - m1 255.255.0.0 130.4.0.0 190.17.6.5 m1 255.255.0.0 140.6.0.0 180.14.2.5 m2 0.0.0.0 0.0.0.0 110.70.4.6 m0 ECE 4110 – Internetwork Programming

  33. Example 6 (Solution) ECE 4110 – Internetwork Programming

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