The MPLS WG Archive

[Marc Binderberger <marc@sniff.de>]

Hi Roger,

>  draft-ietf-l3vpn-rfc2547bis-01.txt specifies the multi-AS Backbone 
> scenario.
>
> 10. c) Multihop EBGP redistribution of labeled VPN-IPv4 routes between
>          source and destination ASes, with EBGP redistribution of
>          labeled IPv4 routes from AS to neighboring AS.
>
> The ASBR  maintains labeled IPv4  /32 routes to the PE routers within 
> its AS and uses EBGP to  distribute the labeled routes to other ASes.
>


> Between, two ASs, it uses BGP to distribute the labels, but in that 
> case, how is the labeled path within the AS Maintained. Is it using 
> BGP itself. Or is  LDP/RSVP used to
> distribute the labels within the same AS?

Redistributing the eBGP-learned /32 into your IGP (thus using LDP/RSVP) 
works. A colleague of mine has tested this. Obviously this has some 
limitations with scalability.

Using iBGP IPv4+label - haven't tested yet as no IOS for 7600 (our PE 
plattform) was available supporting this. As I understand the theory 
this results in a packet with 3 labels minimum: the MP-BGP VPN label at 
the bottom, then the IPv4 next hop label and topmost the LDP label to 
the ASBR.


Regards, Marc
--
Marc Binderberger    <marc@sniff.de>    Powered by *BSD ;-)