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Forum Replies

  1. Hi Rene,
    Can you please explain why do neighbors need to be activated ? In the old syntax ( without address families) these was no "activate". After declaring the neighbors they were activated by default ? But in the new format they are "born" not activated so we need to activate them ?
    Thank you.
    BR
    Adrian

  2. Hi Adrian,

    In the "global" configuration mode of BGP we configure IPv4 unicast which is activated by default. All the other stuff like IPv6 unicast/multicast, IPv4 multicast and VPN routes are disabled by default so that's why we need to activate them. I guess it makes sense, BGP is/was mostly used for IPv4 unicast and not everyone uses all the other address families.

    Rene

  3. Hi Tim,

    This shouldn't be a problem, it's hard to find a Cisco router nowadays that doesn't support MP-BGP.

    IPv6 multicast is only one of the address families that are supported nowadays:

    R1(config)#router bgp 1
    R1(config-router)#address-family ?
      ipv4      Address family
      ipv6      Address family
      l2vpn     Address family
      nsap      Address family
      rtfilter  Address family
      vpnv4     Address family
      vpnv6     Address family

    Rene

  4. had the same question. thank you. so by default bgp ipv4 unicast is only allowed and activate uses the ipv4 multicast 244.0.0.2 address. which will now allot that by activate command. am I right?

  5. BGP by default, only has the IPv4 unicast family activated so you can advertise IPv4 unicast prefixes, that's it. By enabling other address families, you can advertise things like multicast routes or VPN routes. BGP doesn't use multicast addresses itself, it will always use a TCP session between two neighbors, that's it.

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