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I-BGP messages and adj-RIB-out


There's something I don't get. In the BGP slides, on page 20 we are told "Only routes learned from E-BGP are put in Adj-RIB-out" and then in the example on page 26 we have "Since there is no change in Loc-RIB there is no change in Adj-RIB-out". I guess this means if the I-BGP message had lead to a change in Loc it would have been forwarded to Adj-RIB-out.... Isn't this in contradiction?

Thanks for the help,

Christophe Gudin.
Posted by Christophe Gudin on Tuesday 5 December 2006 at 17:58
It is not a contradiction.

Logic says:
If (A=>B) is true that doesn't imply (notA=>notB) is true

A = no change in Loc-RIB
B = no change in Adj-RIB-out

The lecture slides only state that (A=>B) is alwas true (1)

So, change in Loc-RIB doesn't imply (nor prevent) change in Adj-RIB-out. This means that rule "if a route is learned by I-BGP it would not be put into Adj-RIB-out" is not in contradiction with (1).
Posted by Slavisa Sarafijanovic on Wednesday 6 December 2006 at 7:09