%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %% [MJS 31 Jan 2003] Based on plain-bw from http://puchol.com/cpg/software/mgp/ %% %% Default fonts %deffont "standard" xfont "helvetica-medium-r", tfont "arial.ttf" %deffont "thick" xfont "helvetica-bold-r", tfont "arialbd.ttf" %deffont "typewriter" xfont "courier-medium-r", tfont "courbd.ttf" %% %% Default settings per each line numbers. %default 1 leftfill, size 2, fore "white", back "black", font "thick" %default 2 size 7, vgap 10, prefix " " %default 3 size 2, bar "gray70", vgap 10 %default 4 size 5, fore "white", vgap 30, prefix " ", font "standard" %% %% Default settings that are applied to TAB-indented lines. %tab 1 size 4, vgap 35, prefix " ", icon box "green" 50 %tab 2 size 4, vgap 20, prefix " ", icon arc "yellow" 50 %tab 3 size 3, vgap 20, prefix " ", icon delta3 "white" 40 %% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page %nodefault %fore "white", back "black", size 7, font "standard" %center %size 8 An Overview of Routing OSPF and other protocols %size 6 Saturday, 1 February 2003 Mark Suter %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page Copyright Copyright (C) 2003 Mark Suter Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with no Invariant Section, with no Front-Cover Texts, and with no Back-Cover Texts. http://www.gnu.org/copyleft/fdl.html %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page Outline Why routing protocols are needed? Routing in the Internet Designing large-scale IP internetworks Introduction to routing protocols Conclusions %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page Why are routing protocols needed? IP network's primary function is deliver packets from source to destination Routing is needed to know what is the best route from source to destination If network topology changes routing function sets up a new route from source to destination %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page Static vs. dynamic routing static routes can be set by network administrators "the hard way" mainly used as a default route dynamic routing route discovered and selected by dynamic routing protocol %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page Address allocations Internet Assigned Numbers Authority (IANA) allocates IP addresses and AS-numbers ISPs get their IP addresses from upstream provider or from regional registry APNIC (Asian-Pacific Network Information Center) ARIN (American Registry for Internet Numbers) RIPE NCC (Réseaux IP Européens) %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page Routing in The Internet Internet is set of autonomous systems (AS) autonomous system is collection of routers under same administration routing inside of AS is handled by IGP (Interior Gateway Protocol) routing between ASes is done by EGP (Exterior Gateway Protocol) %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page Designing IP internetworks network topology addressing and route summarization route selection convergence network scalability security %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page Network Topology physical topology set of routers networks which connect them logical topology different routing protocols establish logical topology in different way flat topology vs. hierarcical topology %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page Addressing and route summarization summarization reduces routing information for each router several routes as a single advertisement reduces the load on the router very important when network size increases %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page Summarization Example: The Internet # http://www.mcvax.org/~jhma/routing/bgp-hist.html %center %newimage -xscrzoom 70 "bgp-history.png" %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page Metric calculation trivial if single path to destination computed by assigning a characteristics to each physical link (e.g.) link bandwidth link reliability propagation delay some protocols use multiple paths with equal cost for load balancing %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page Convergence when the network topology changes (e.g. link down), routers need to detect the change select a new route inform other routers route selection is protocol independent %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page Network scalability when network size increases, some resources are critical memory CPU bandwidth %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page Security authentication prevents unauthorized routers or hosts to participate to routing process filters routes to be advertised routes not to advertised %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page Introduction to routing protocols two categories in use distance vector protocol (e.g. RIP) broadcasts complete routing table periodically and when network topology changes link-state procol (e.g. OSPF) send table updates only when change occurs %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page Distance vector protocols each router calculates its routing table shortest distance to networks or routers are stored in routing table routers sends router table every XX seconds to neighbors cannot scale cannot resolve loops quickly %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page Link-state protocol each router knows network topology if topology changes, it is updated by flooding the change to all routers each router re-computes routing table in parallel using link-state database %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page RIP RIP = Routing Information Protocol distance vector protocol, IGP traditional routing protocol first version was shipped with BSD distribution as a routed (1982) the best route has lowest hop count (simple metric) %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page RIP max. hop count is 15 (16 is unreachable) max. hop count is used to prevent routing loops regular route table update causes unnecessary resource use RIP is not suitable for low bandwidth or large networks %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page RIPv2 enhanced version of RIP distance vector protocol, IGP almost same as RIP supports variable-length subnet masks and very simple authentication %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page IGRP IGRP = Interior Gateway Routing Protocol proprietary solution by Cisco Systems in the mid-1980's distance vector protocol designed to replace RIP %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page EIGRP enhanced IGRP advanced distance vector protocol like link-state protocols EIGRP sends updates only on changes supports variable-length subnet masks route summarization at any bit boundary %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page OSPF OSPF = Open Shortest Path First developed by IETF link-state protocol supports variable-length subnet masks as IGP, OSPF is used inside a single autonomous system (AS) %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page OSPF administration of large IP network is simplified by dividing network to areas mandatory area is the backbone (area 0) backbone area is the transit domain between other areas %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page OSPF area border router (ABR) has typically interface to local area and to backbone area ABR summarizes information from the local area to the backbone and information is propagated to other areas %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page OSPF when OSPF starts, it elects two special routers designated router (DR) backup designated router (BDR) these routers has following responsibilities determine which routers are connected to network synchronize all routers' link state databases %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page OSPF important things when designing OSPF network sutability and redundancy of backbone definition of area boundaries address assigment the number of routers per area selection of designated router %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page BGP4 BGP = Border Gateway Protocol path vector protocol exchanges network reachability information between BGP systems network reachability information includes AS-path topology classless routing protocol supports route aggregation and supernetting %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page BGP4 learns multiple paths via internal and external BGP peers selects the best path loop detection (important) policy based on AS path, community or the network rejects/accepts selected routes no load balancing %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page Conclusion about routing techniques recommendation is to use OSPF inside AS (not RIP) use BGP4 between autonomous systems OSPF and BGP4 are commonly used and it is possible to use them in multivendor environment [E]IGRP is proprietary solution, although perhaps technically superior %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page More Information It's the Internet Age and the problem is now in finding the useful amongst all the information that's available. Now http://www.tldp.org/HOWTO/Net-HOWTO/ http://www.bergen.org/ATC/Course/InfoTech/Coolip/ Tomorrow http://www.ietf.org/html.charters/mobileip-charter.html %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page Security Just being connected increases risk --- wireless adds a whole new dimension. http://zwitterion.org/link/54559 # Wireless Articles http://www.freeswan.org/ http://www.cert.org/tech_tips/home_networks.html http://www.auscert.org.au/render.html?it=1968&cid=1920 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %page Thank-you # Theodore Sturgeon (1918-1985) %size 20 %mark Q %again %size 5 ----------> Slides @ http://zwitterion.org/talks/routing/