Are you saying that using the following as an example:

router bgp 1
 bgp router-id 1.1.1.1
 no bgp default ipv4-unicast
 neighbor 1.1.1.2 remote-as 100
 !
 address-family ipv4
 exit-address-family
 !
 address-family vpnv4
  neighbor 1.1.1.2 activate
  neighbor 1.1.1.2 send-community extended
 exit-address-family
 !
 address-family ipv4 vrf BLUE
  neighbor 2.2.2.2 remote-as 200
  neighbor 2.2.2.2 activate
 exit-address-family

You configured your neighbor like 2.2.2.2 and the solution you were looking
at had the neighbor configured like 1.1.1.2?

The first question is: Did your solution work? If I understand what you did
right, I'd imagine it did not work.

The neighbor 1.1.1.2 in my example that is configured under the routing
process and activated under the VPNv4 address family would be for another
MPLS PE peer that you're exchanging VPN labels with (another PE router
elsewhere in the MPLS network). That peering would not exchange 32-bit IPv4
prefixes, but 96-bit VPNv4 prefixes that include the RD for uniqueness,
along with extended community values to indicate the label used for that
VPN path.

The example neighbor 2.2.2.2 in the example above would be the CE peer.
This neighbor is configured *only* under the IPv4 VRF address family (not
at the routing process level) and is how the PE builds a BGP peering with
the CE router *within* the VRF. The peer router in this case would be
running "normal" BGP and totally unaware of the MPLS label exchange going
on behind the scenes.

The VPNv4 address family is a special case for BGP and it's what makes MPLS
L3VPN work. The IPv4 VRF address family configuration under BGP is pretty
much the same as any other PE-CE routing protocol configuration like if you
did an address family under RIP or EIGRP to use those as the PE-CE protocol.

Does that help?

Bob
CCIE #38296


On Mon, Mar 25, 2013 at 8:15 AM, Houssam Chahine
<[email protected]>wrote:

> Greetings,
>
> I have a small question about address family.
>
> In Lab 3 Vol2, the peering is configured under the router process and
> activated under vpnv4 address family.
>
> What i did was configuring the peering under the ipv4 vrf address family.
>
> I would like to know what is the difference between configuring the
> neighbor statement under the router process and under the address family.
> Furthermore is what i did correct or wrong.
>
> Thank you all in advance.
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