Internet Routing
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                                Intra-AS       Inter-AS
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                           RIP         OSPF      BGP


      RIP                               OSPF                        BGP
- Routing Information Protocol  - Open Shortest Path First   - Border Gateway Protocol
- intra-AS routing              - intra-AS routing           - inter-AS routing     
- distance vector               - link state                 - path vector (policy based)
- small flat AS (max 16 hops)   - large hierarchical AS      - eBGP and iBGP
- single best path              - multiple best paths        - AS hops, PATH attributes
- RFC 1058 (31 pages)           - RFC 2328 (244 pages)       - RFC 4271 (101 pages)
- uses UDP (port 520)           - uses IP                    - uses TCP sessions
- periodic updates              - area/backbone mgmt         - BGP messages
- obsolete                      - widely used                - widely used
- insecure                      - secure                     - secure version now