ECE544_Lec5_DR08

ECE544_Lec5_DR08 - ECE544: Communication Networks-II,...

Info iconThis preview shows pages 1–12. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: ECE544: Communication Networks-II, Spring 2008 D. Raychaudhuri Lecture 5 Includes teaching materials from L. Peterson, J. Kurose, K. Almeroth Today’s Lecture • Scalable Addressing • Sub-netting • Super-netting (CIDR) • Route Aggregation Examples • BGP • Global Internet routing • BGP protocol outline • Multicast • General discussion • Internet Group Management Protocol (IGMP) • Routing Protocols – MOSPF, PIM Scalable IP Routing Internet Structure Recent Past NSFNET backbone Stanford BARRNET regional Berkeley P ARC NCAR UA UNM Westnet regional UNL KU ISU MidNet regional … Internet Structure Today Backbone service provider Peering point Peering point Large corporation Large corporation Small corporation “Consumer ” ISP “Consumer” ISP “ Consumer” ISP IP Address network host 10 network host 110 network host 1110 multicast address A B C D class 1.0.0.0 to 127.255.255.255 128.0.0.0 to 191.255.255.255 192.0.0.0 to 223.255.255.255 224.0.0.0 to 239.255.255.255 32 bits “class-full” addressing: How to Make Routing Scale • Flat versus Hierarchical Addresses • Inefficient use of Hierarchical Address Space – class C with 2 hosts (2/255 = 0.78% efficient) – class B with 256 hosts (256/65535 = 0.39% efficient) • Still Too Many Networks – routing tables do not scale – route propagation protocols do not scale Subnetting • Add another level to address/routing hierarchy: subnet • Subnet masks define variable partition of host part • Subnets visible only within site Network number Host number Class B address Subnet mask (255.255.255.0) Subnetted address 111111111111111111111111 00000000 Network number Host ID Subnet ID Subnet Example Forwarding table at router R1 Subnet Number Subnet Mask Next Hop 128.96.34.0 255.255.255.128 interface 0 128.96.34.128 255.255.255.128 interface 1 128.96.33.0 255.255.255.0 R2 Subnet mask: 255.255.255.128 Subnet number: 128.96.34.0 128.96.34.15 128.96.34.1 H1 R1 128.96.34.130 Subnet mask: 255.255.255.128 Subnet number: 128.96.34.128 128.96.34.129 128.96.34.139 R2 H2 128.96.33.1 128.96.33.14 Subnet mask: 255.255.255.0 Subnet number: 128.96.33.0 H3 Super-netting (CIDR) • Class addressing doesn’t match real needs: – Class C is 255 addresses, too small – Clsss B is 64K addresses, too big • Need method of allocating addresses in multiple sizes • Assign block of contiguous network numbers to nearby networks • Called CIDR : C lassless I nter- D omain R outing Supernetting (CIDR) • Assign block of contiguous network numbers to nearby networks • Called CIDR: Classless Inter-Domain Routing • Protocol uses a (length, value) pair length = # of bits in network prefix • Use CIDR bit mask to identify block size • All routers must understand CIDR addressing...
View Full Document

This note was uploaded on 04/03/2008 for the course ECE ECE544 taught by Professor Raychaudhuri during the Spring '08 term at Rutgers.

Page1 / 90

ECE544_Lec5_DR08 - ECE544: Communication Networks-II,...

This preview shows document pages 1 - 12. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online