[nsp] MPLS -- EGP vs. IGP problem?

[John Osmon]

I've got an MPLS testbed setup with several cisco 2500s running
c2500-p-l.tag.  There is no problem in getting packets to be 
tag-swithched if the destination is known via the IGP.  BGP learned
destinations, however, don't get tag-switched, and thus can't get across
the (non BGP enabled) core P routers.  

I thought that the only requirement was that the BGP next-hop had
to able to be tag-switched.  I'm obviously missing something - but is
it due to the unsupported IOS version I'm running, or am I missing
something more fundamental?  (Prefix length msimatches?)


My example case has 192.168.2.2 tag-switched, but BGP learned prefixes
that have 192.168.2.2 as their next-hop don't get tag-switched.  Any
pointers would be appreciated.  Relevant (in my mind) info from one
of the PE routers follows:

PE0#sh ip route
B    192.168.10.0/24 [200/0] via 192.168.2.2, 2d10h
i L2 192.168.2.0/24 [115/30] via 10.0.0.1, Serial0


PE0#sh ip cef 192.168.2.2 detail
192.168.2.0/24, version 15, cached adjacency to Serial0
0 packets, 0 bytes
  tag information set
    local tag: 31
    fast tag rewrite with Se0, point2point, tags imposed: {30}
  via 10.0.0.1, Serial0, 2 dependencies
    next hop 10.0.0.1, Serial0
    valid cached adjacency
    tag rewrite with Se0, point2point, tags imposed: {30}

PE0#sh ip cef 192.168.10.0 detail
192.168.10.0/24, version 23, cached adjacency to Serial0
0 packets, 0 bytes
  tag information set
    local tag: 4
  via 192.168.2.2, 0 dependencies, recursive
    next hop 10.0.0.1, Serial0 via 192.168.2.0/24
    valid cached adjacency