1 / 13

Global Internet Textbook Ch4.1

Global Internet Textbook Ch4.1. Instructor: Joe McCarthy (based on Prof. Fukuda’s slides). Routing (section 3.3). Example rows from (a) routing and (b) forwarding tables. What if every router needed an entry for every IP address?. Routing (section 3.3).

yetty
Download Presentation

Global Internet Textbook Ch4.1

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Global InternetTextbook Ch4.1 Instructor: Joe McCarthy (based on Prof. Fukuda’s slides) CSS 432: Global Internet

  2. Routing (section 3.3) Example rows from (a) routing and (b) forwarding tables • What if every router needed an entry for every • IP address? CSS 432: Global Internet

  3. Routing (section 3.3) Example rows from (a) routing and (b) forwarding tables • What if every router needed an entry for every • IP address? (232, or 4,000,000,000 possible hosts) • Network prefix? CSS 432: Global Internet

  4. Internet Routing 430K << 4B … But do we want 430K entries in every router table? Traffic just for update messages? Sep 2012: 430,000+ prefixes http://en.wikipedia.org/wiki/Border_Gateway_Protocol CSS 432: Global Internet

  5. Internet, circa 1990 Nationwide backbone (NSFNET) Regional networks (BARRNET, Westnet, …) End-user sites (Stanford, Berkeley, …) Each node is an Autonomous System (AS) CSS 432: Global Internet

  6. Internet Routing Sep 2012: 40,000+ ASs Sep 2012: 430,000+ prefixes http://en.wikipedia.org/wiki/Border_Gateway_Protocol CSS 432: Global Internet

  7. Hierarchical Routing (Autonomous Systems aka Routing Domains) • Divide the routing problem in two parts: • Routing within a single AS • Intra-domain routing protocol (each AS selects its own) • Routing between ASs • Inter-domain routing protocol(Internet-wide standard) CSS 432: Global Internet

  8. Intra-domain Protocols • RIP: Route Information Protocol • Distributed with BSD Unix • Distance-vector algorithm • Based on hop-count • OSPF: Open Shortest Path First • More recent Internet standard • Uses link-state algorithm • Supports authentication CSS 432: Global Internet

  9. Large corporation “ ” Consumer ISP Peering point Backbone service provider Peering point Consumer ” ISP “ “ Consumer ISP ” Large corporation Small corporation Inter-domain Protocol • Border Gateway Protocol, version 4 (BGP-4) • Internet is an arbitrarily interconnected set of ASs • Each AS has a Speaker (advertiser) • Goal: Reachability than optimality • Stub AS: • A single connection to another AS • Only carries local traffic • Multihomed AS: • Connections to multiple ASs • Refuses to carry transit traffic • Transit AS: • Connections to multiple ASs • Carries both transit & local traffic CSS 432: Global Internet

  10. 128.96 Customer P 192.4.153 (AS 4) Regional provider A (AS 2) Customer Q 192.4.32 (AS 5) 192.4.3 Backbone network (AS 1) Customer R 192.12.69 (AS 6) Regional provider B (AS 3) Customer S 192.4.54 (AS 7) 192.4.23 BGP Example • Speaker for AS2 advertises reachability to P and Q • Network 128.96, 192.4.153, 192.4.32 & 192.4.3can be reached directly from AS2 • Speaker for AS1 (backbone) advertises • Networks 128.96, 192.4.153, 192.4.32, and 192.4.3 can be reached along the path (AS1, AS2) • Networks 192.12.69, 192.4.54, 192.4.23can be reached along the path (AS1, AS3) • Speaker can cancel previously advertised paths CSS 432: Global Internet

  11. Routing Areas • AS divided into areas • Area 0 • Known as the backbone area (connected to the backbone) • Area Border Routers (ABRs): R1, R2, R3 • OSPF link state packets • Do not leave the area in which they originated (if they are not ABRs) • ABRs summarize routing information that they have learned from one area and make it available in their advertisements to other areas. CSS 432: Global Internet

  12. iGP + eGP Routing CSS 432: Global Internet

  13. IP Version 6 • Features • 128-bit addresses (classless) • multicast • real-time service • authentication and security • autoconfiguration • end-to-end fragmentation • protocol extensions • Header • 40-byte “base” header • extension headers (fixed order, mostly fixed length) • fragmentation • source routing • authentication and security • other options CSS 432: Global Internet

More Related