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snofrar
Beginner

BGP filtering with route-maps

Hi,

I have a BGP neighbour with a route-map to filter incoming updates, this route-map only has one permit statement with a ACL match clause, but I've realized that this ACL doesn't exist.

I thought it should block everythig but I can see all the networks from this neighbour, is this a normal behaviour ?

4 REPLIES 4
thisisshanky
Advisor

Yes thats correct. The ACL needs to be in place for filtering to happen.

Sankar Nair
UC Solutions Architect
Pacific Northwest | CDW
CCIE Collaboration #17135 Emeritus
wkumari
Beginner

Yup, this is normal behavior. All ACLs have an implicit deny at the end, but only if they exist!

This means you can do

no access-list 101

int f0/0

ip access 101 in

and nothing will happen, but as soon as you add the first line to 101 you will start denying everything (other than what you explicitly allowed in the first line.)

Warren.

Harold Ritter
Cisco Employee

If the ACL is not configured all routes are accepted indeed. Make sure you do configure an ACL.

Hope this helps,

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México

Thank you all for the information, I thought that even the ACL doesn't exist there was an implicit deny.

The configuration is being arranged and all is in place, thank you