BGP ADVERTISING
BGP need not adhere to a minimum hop approach. Figure 7-2 shows why. Routers 1 to 10 are GP routers that connect ASs 1 to 5 together. The topology forms a loop between AS 2, AS 3, and AS 5. Under the older distance-vector protocols, a break in the topology, say between router 1 and router 2, would invoke the count to infinity procedure between routers 4, 5, 6, 7, 9, and 10, as well as between router 3 and 8.
Figure 7-2. BGP Advertising
BGP knows better. It has discovered that the prefix 192.169.0.0/16 is reachable through AS 1. AS 2 knows that it is in the path to the address, so it would reject any message that had AS 2 in the ...
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