From: Weidong Xiao (Weidong.Xiao@vi.net)
Date: Wed Sep 10 2003 - 10:01:43 GMT-3
R1(AS1)-------R2(AS2)
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R3(AS3)-------R4(AS3)
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lo0:192.168.1.1/24
Say 192.168.1.0/24 needs to be advertised primarily by R3, only when linke between R1 and R3 (or between R1 and R2) fails should R4 advertise this network.
On R4, will the following config work?
neighbor R2 advertise-map MATCH-MYNET non-exist-map MATCH-MYNET
route-map MATCH-MYNET
match ip prefix-list 1
ip prefix-list 1 permit 192.168.1.0/24
What concerns me is that when R4 receives 192.168.1.0/24 from R2, the prefix will be discarded before install to bgp table, so non-exist-map MATCH-MYNET will always be satisfied, and the prefix be advertised. But, anyway, R4 do receive that prefix from R2,...
The question boiled down to where does non-exist-map check? bgp table or received prefix?
According to command reference,"Any BGP route that is matched by the advertise-map route map will be advertised to the neighbor if the non-exist-map route map does not match any route in the BGP routing table.", it's likely that non-exist-map checks BGP table.
I wonder if there is a way to fulfill the task?
Many thanks,
Weidong
CC[N|D]P, CSS1
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