Chap 23 ip over atm
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This document discusses how IP data is carried over an ATM network. It explains that IP datagrams are encapsulated into ATM cells using AAL5. The cells are then routed individually through the ATM network based on their addresses to the exiting point router. ATMARP is used to map IP addresses to physical ATM addresses to allow cells to be properly delivered from entering to exiting point routers across the ATM network. Logical IP subnets can also be defined to facilitate protocols like ATMARP that require simulating broadcast domains.
Chap 23 ip over atm
- 1. CChhaapptteerr 2233 IIPP OOvveerr AATTMM Objectives Upon completion you will be able to: • Review the features of an ATM WAN • Understand how an a datagram can pass through an ATM WAN • Understand how an IP packet is encapsulated in cells • Understand how cells are routed in an ATM network • Understand the function of ATMARP TCP/IP Protocol Suite 1
- 2. 23.1 ATM WANS We review some features of the ATM WAN nneeeeddeedd ttoo uunnddeerrssttaanndd IIPP oovveerr AATTMM.. TThhee oonnllyy AAAALL uusseedd bbyy tthhee IInntteerrnneett iiss AAAALL55,, ssoommeettiimmeess ccaalllleedd tthhee ssiimmppllee aanndd eeffffiicciieenntt aaddaappttaattiioonn llaayyeerr ((SSEEAALL)).. TThhee ttooppiiccss ddiissccuusssseedd iinn tthhiiss sseeccttiioonn iinncclluuddee:: LLaayyeerrss TCP/IP Protocol Suite 2
- 3. Figure 23.1 An ATM WAN in the Internet TCP/IP Protocol Suite 3
- 4. Figure 23.2 ATM layers in routers and switches TCP/IP Protocol Suite 4
- 5. NNoottee:: End devices such as routers use all three layers, while switches use only the bottom two layers. TCP/IP Protocol Suite 5
- 6. Figure 23.3 AAL5 TCP/IP Protocol Suite 6
- 7. NNoottee:: The AAL layer used by the IP protocol is AAL5. TCP/IP Protocol Suite 7
- 8. Figure 23.4 ATM layer TCP/IP Protocol Suite 8
- 9. Figure 23.5 ATM headers TCP/IP Protocol Suite 9
- 10. 23.2 CARRYING A DATAGRAM IN CELLS We show how an example of a datagram encapsulated iinn ffoouurr cceellllss aanndd ttrraannssmmiitttteedd tthhrroouugghh aann AATTMM nneettwwoorrkk.. TThhee ttooppiiccss ddiissccuusssseedd iinn tthhiiss sseeccttiioonn iinncclluuddee:: WWhhyy UUssee AAAALL55?? TCP/IP Protocol Suite 10
- 11. Figure 23.6 Fragmentation TCP/IP Protocol Suite 11
- 12. NNoottee:: Only the last cell carries the 8-byte trailer added to the IP datagram. Padding can be added only to the last cell or the last two cells. TCP/IP Protocol Suite 12
- 13. NNoottee:: The value of the PT field is 000 in all cells carrying an IP datagram fragment except for the last cell; the value is 001 in the last cell. TCP/IP Protocol Suite 13
- 14. Figure 23.7 ATM cells TCP/IP Protocol Suite 14
- 15. 23.3 ROUTING THE CELLS The ATM network creates a route between two rroouutteerrss.. WWee ccaallll tthheessee rroouutteerrss eenntteerriinngg--ppooiinntt aanndd eexxiittiinngg--ppooiinntt rroouutteerrss.. TThhee ttooppiiccss ddiissccuusssseedd iinn tthhiiss sseeccttiioonn iinncclluuddee:: AAddddrreesssseess AAddddrreessss BBiinnddiinngg TCP/IP Protocol Suite 15
- 16. Figure 23.8 Entering-point and exiting-point routers TCP/IP Protocol Suite 16
- 17. 23.4 ATMARP ATMARP finds (maps) the physical address of the eexxiittiinngg--ppooiinntt rroouutteerr ggiivveenn tthhee IIPP aaddddrreessss ooff tthhee eexxiittiinngg--ppooiinntt rroouutteerr.. NNoo bbrrooaaddccaassttiinngg iiss iinnvvoollvveedd.. TThhee ttooppiiccss ddiissccuusssseedd iinn tthhiiss sseeccttiioonn iinncclluuddee:: PPaacckkeett FFoorrmmaatt AATTMMAARRPP OOppeerraattiioonn TCP/IP Protocol Suite 17
- 18. Figure 23.9 ATMARP packet TCP/IP Protocol Suite 18
- 19. TTaabbllee 2233..11 OOPPEERR ffiieelldd TCP/IP Protocol Suite 19
- 20. NNoottee:: The inverse request and inverse reply messages can bind the physical address to an IP address in a PVC situation. TCP/IP Protocol Suite 20
- 21. Figure 23.10 Binding with PVC TCP/IP Protocol Suite 21
- 22. Figure 23.11 Binding with ATMARP TCP/IP Protocol Suite 22
- 23. NNoottee:: The request and reply message can be used to bind a physical address to an IP address in an SVC situation. TCP/IP Protocol Suite 23
- 24. NNoottee:: The inverse request and inverse reply can also be used to build the server’s mapping table. TCP/IP Protocol Suite 24
- 25. Figure 23.12 Building a table TCP/IP Protocol Suite 25
- 26. 23.5 LOGICAL IP SUBNET (LIS) An ATM network can be divided into logical (not pphhyyssiiccaall)) ssuubbnneettwwoorrkkss.. TThhiiss ffaacciilliittaatteess tthhee ooppeerraattiioonn ooff AATTMMAARRPP aanndd ootthheerr pprroottooccoollss ((ssuucchh aass IIGGMMPP)) tthhaatt nneeeedd ttoo ssiimmuullaattee bbrrooaaddccaassttiinngg oonn aann AATTMM nneettwwoorrkk.. TCP/IP Protocol Suite 26
- 27. Figure 23.13 LIS TCP/IP Protocol Suite 27
- 28. NNoottee:: LIS allows an ATM network to be divided into several logical subnets. To use ATMARP, we need a separate server for each subnet. TCP/IP Protocol Suite 28