Hi, We are configuring Cisco 6PE in our network as in
rfc 4798 (http://www.rfc-editor.org/rfc/rfc4798.txt).
In our configuration the CE is in our own IGP domain and there is a IPv6 BGP session between the CE and the 6PE who acts as a RR Server. Routes from the CE
are reflected by the 6PE to the rest of the network.
As we are using 6PE prefixes MUST have a label bundary of 2, using the first label to identify the 6PE exit router and a second label to identify the IPv6 AFI.
So the problem is routes from one CE arrives to the 6PE and are reflected to the rest of the network. As the ingress 6PE does not have a label for the CE it publish
the prefix with second label=0. I have seen that the receiving 6PE does not understand the message and set a buggy prefix in its routing table.
The problem can be worked around if you set a "next-hop-self" at the 6PE for the routes announced by the CE or by eliminating the "send-label" on the ipv6 BGP config.
I believe that Cisco should not be sending label=0 as it is a reserved label for "ipv4 explicit null".
Here some texts extracted from the RFC:
Interconnecting IPv6 islands over an IPv4 MPLS cloud takes place
through the following steps:
1. Exchange IPv6 reachability information among 6PE routers with MP-
The 6PE routers MUST exchange the IPv6 prefixes over MP-BGP
sessions as per [RFC2545] running over IPv4. The MP-BGP Address
Family Identifier (AFI) used MUST be IPv6 (value 2). In doing so,
the 6PE routers convey their IPv4 address as the BGP Next Hop for
the advertised IPv6 prefixes. The IPv4 address of the egress 6PE
router MUST be encoded as an IPv4-mapped IPv6 address in the BGP
Next Hop field. This encoding is consistent with the definition
of an IPv4-mapped IPv6 address in [RFC4291] as an "address type
used to represent the address of IPv4 nodes as IPv6 addresses".
In addition, the 6PE MUST bind a label to the IPv6 prefix as per
[RFC3107]. The Subsequence Address Family Identifier (SAFI) used
in MP-BGP MUST be the "label" SAFI (value 4) as defined in
[RFC3107]. Rationale for this and label allocation policies are
discussed in Section 3.
Any help will be appreciated .