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Forum Replies

  1. Rene,
    Great lesson to understand community. I have question if we have two loopbacks for instance 2.2.2.2/32 on R1 and I would like to advertize this and block 1.1.1.1/32. Do I need an ACL to match under route-map?

    Please confirm
    Hamood

  2. Hi Hamood,

    That’s right, in this example I used a really simple route-map but you could do something like this:

    access-list 1 permit host 1.1.1.1
    
    route-map NO_ADVERTISE deny 10
    match ip address 1
    set community no-advertise
    
    route-map NO_ADVERTISE permit 20
    

    The first route-map statement will deny everything that matches access-list 1, the second route-map statement is required to permit everything else.

    Rene

  3. Hi Thai,
    Good catch. I believe you are correct. I will ask Rene to review/correct this.

  4. I think the route map with deny statement will deny everything that permitted in access-list statement, so the outbound routes will be filtered if we use the route map with redistribution or with community or any other case, I also check it out with a lab and I see the route 1.1.1.1 in your case will not announce even to R2 !!! If I did not understand, is it possible to clarify this case more ???

  5. Let me give an example to avoid confusion. To keep it simple and fast, I’ll use EIGRP and a distribute-list. Here’s R1:

    R1#show run | begin router eigrp
    router eigrp 1
     network 0.0.0.0
    

    and R2:

    R2#show run | begin router eigrp
    router eigrp 1
     network 0.0.0.0
    

    R1 has two loopback interfaces that are advertised to R2:

    R2#show ip route eigrp 
    
          1.0.0.0/24 is subnetted, 1 subnets
    D        1.1.1.0 [90/130816] via 192.168.12.1, 00:02:32, GigabitEthernet0/1
          11.0.0.0/24 is subnetted, 1 subnets
    D        11.11.11.0 [90/130816] via 192.168.12.1, 00:02:32, Gigab
    ... Continue reading in our forum

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