BGP Communities No-Advertise


Scenario:

As the owner of a small dutch ISP you like to configure some of the networking stuff yourself. For one of your customers you have to make some changes to the network. They want to advertise their networks to you but you want to prevent this information to be spread to other customers or other parts within your network.

Goal:

  • All IP addresses have been preconfigured for you.
  • Configure EBGP between AS 1 and AS 2.
  • Configure EBGP between AS 2 and AS 3.
  • Configure IBGP in AS 2.
  • Advertise the loopback0 interface on router Erik in BGP.
  • Configure router Rene so it doesn’t advertise network 1.1.1.0 /24 to any other BGP neighbor. Use one of the communities to achieve this.

IOS:

c3640-jk9s-mz.124-16.bin

Topology:

BGP Community No Advertise

Video Solution:

Configuration Files

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Written by René Molenaar - CCIE #41726

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About the Author: Rene Molenaar

René - CCIE #41726 is the creator of GNS3Vault.com where he shares CCNA, CCNP and CCIE R&S labs. He also blogs about networking on http://networklessons.com

3 Comments

  1. when i configured this lab i did it slightly differently, but it didnt work. On the Rene router i created the following:

    access-list 1 permit 1.1.1.0 0.0.0.255
    !
    route-map NOADVERTISE permit 10
    match ip address 1
    set community no-advertise
    !
    neighbor 192.168.23.3 send-community
    neighbor 192.168.23.3 route-map NOADVERTISE out
    neighbor 192.168.24.4 send-community
    neighbor 192.168.24.4 route-map NOADVERTISE out

    Any ideas why it doesnt work?

    1. @TK79

      The reason why it does not work is because you need to set the community when in comes IN to Rene, otherwise Rene WILL advertise it to its neighbors but with the no-advertise community.

      The neighbors will not advertise it then.

      Hope this helps 🙂

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