Multiprotocol BGP (MP-BGP) Configuration

Why did u activate the Ipv4 neighbor in IPv6 address family ??. Will it impact anything ??

i think the best configuration is , configure all the Ipv4 and Ipv6 neighbor globally and activate them in their respective address-family ??

Hello Narad

The neighbor activate command is used to activate a neighbor. By default, the exchange of addresses with BGP neighbors is enabled for IPv4 address family by default. It is disabled by default for all other address families, such as IPv6. So in this particular case, the command is necessary. Since IPv4 is being used for a neighbor peering to exchange IPv6 addresses, and since this is all configured within the IPv6 address family mode, this command must be applied. More information about it can be found here:

Now It is obviously cleaner and more consistent to create an IPv6 adjacency with IPv6 prefixes. However, this is not always possible. What if you have a connection between BGP peers that is using IPv4? Such a configuration is not applied as best practice, but out of necessity.

I hope this has been helpful!

Laz

Hi,

I have been configuring Ipv4 & Ipv6 address family, so do we need to use
no neighbor IPv6 activate and no neighbor IPv6 no shutdown in ipv4 address family and then neighbor ipv6 activate & attaching route map in Ipv6 address family
or both commands of no neighbor activate & shutdown can be used in IPv6 address family also instead of in Ipv4 address family

Hello Nitin

Whenever you issue the neighbor command, the default address-family used is IPv4. For this reason, you must explicitly deactivate the neighbor used within the ipv4 address-family configuration mode and activate it on the ipv6 address-family mode.

It must be done in this way, because you cannot deactivate the IPv4 neighborship from the IPv6 configuration mode.

I’m not sure if I’ve fully answered your question, but if not, feel free to clarify and let us know…

I hope this has been helpful!

Laz

Hi Rene,

Please help explain when is the command ‘address-family ipv6 multicast’ used? Can it be use to advertise routes into IPv6 MP-BGP?

router bgp 65000
no bgp default ipv4-unicast 
address-family ipv6 multicast 
network 2001:DB8::/64

Hello Kenneth

Under the BGP configuration, when you configure an address family, you are choosing to configure the BGP session for a particular type of traffic. If you don’t use the address-family command, and you configure BGP directly, then you are actually configuring the IPv4 address-family, since this is the default.

By issuing the address-family ipv6 multicast command, you are placing the router in IPv6 address family configuration mode. Specifically, you are indicating to the router that you want to create IPv6 multicast routing sessions.

This particular command is used when you want BGP to advertise IPv6 multicast address prefixes.

For more information, take a look at this Cisco command reference that further explains the use of this command:

I hope this has been helpful!

Laz

Any used cases or labs for using address-family ipv6 multicast and also elaborate more on its usage with RPF.

Hello Kenneth

The address-family ipv6 multicast command is used when you want to route multicast traffic between ASes. Remember, multicast is not supported on the public Internet, for IPv4 or IPv6, so such a configuration must be employed within a private enterprise network that may have several interconnected BGP ASes.

So let’s say you have a large enterprise network with multiple sites that are interconnected via some VPN/tunneling service that supports multicast. Your network is large enough to contain multiple private BGP ASes. Let’s also say that you are running multicast on this network. How will you route multicast traffic between ASes? Using MP-BGP with the appropriate command.

For more info on this feature and how it can be applied, take a look at this Cisco documentation:

Concerning RPF lookup, the multicast configuration (for both IPv6 and IPv4) simply allows BGP to perform the RPF lookup as needed to eliminate loops in much the same way that it is described here:

I was unable to find a lab or an example for the IPv6 multicast BGP address family, but I was able to find some examples of the application of ipv4 multicast address-family at the following links:
https://learningnetwork.cisco.com/s/question/0D53i00000Kt0H2CAJ/bgp-multicast-addressfamaily
The following is from a Cisco Live presentation, and on slide 59 you will see an application for use with MPLS.

I hope this has been helpful!

Laz