BGP route map question

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Nov 3rd, 2005
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Hi,

I came across a route-map statement on the config. of router A peering through EBGP to router B.

!

neighbor <router B's IP> route-map

PREF in

!

route-map PREF permit 10

match community 10

set local-preference 110

!

route-map PREF permit 20

match community 20

set local-preference 120

!

route-map PREF permit 30

!


My question concerns the need for the last permit statement. What is the default action in route maps when no match and/or set actions are specified?


Thanks,

Rajesh

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rwiesmann Thu, 11/03/2005 - 06:37
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Hi,

the third statement will assign a local pref of 100 (default) to all prefixes which will not have a community set to 10 or 20.


Default local pref see:

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094431.shtml


If you do not have the last permit statement it would simply ignore all prefixes without a community of either 10 or 20.

Hope that helps

Roger

rajesh444 Thu, 11/03/2005 - 07:36
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Roger,


Thanks. Without the last permit statement, would

all other prefixes be dropped or simply ignored and

passed through?


Assuming router A is running IBGP with other

routers in its AS, wouldn't it advertise EBGP

learned prefixes to IBGP peers with default

local-pref value of 100 anyway?


Rajesh

rwiesmann Thu, 11/03/2005 - 07:50
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Hi Rajesh,

without the last permit statement the prefixes will be ignored/dropped and not passed through.


so in the sample you give the answer is no....the router would not accept it and because of this not advertise this prefixes.


regards

roger

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