[c-nsp] tag-switching advertise-tags for?

[Jon Lewis]

On Mon, 24 Oct 2005, Oliver Boehmer (oboehmer) wrote:

>> You're saying LDP across all our routers needs these as destinations
>> to be able to properly tag-switch the labeled MPLS VPN traffic?
>
> Hmm, not sure what you mean. This command tells TDP/LDP to only
> advertise labels for those IPv4 prefixes matching the ACL. If those IPv4
> prefixes are your BGP next-hops, then yes, all your MPLS-VPN traffic
> will be label-switched.

My understanding was that MPLS-VPN traffic has to be label-switched.  Back 
when I started doing MPLS VPNs, I wasn't aware of the advertise-tags 
command, and as a result the portions of our network that have P/PE 
routers are tag-switching nearly all traffic (I suppose the only exception 
is traffic from connected end users on the routers they're connected to).

I just want to avoid tag/label-switching as much non-MPLS-VPN traffic as 
possible in order to get our routers obeying local hacks in their routing 
tables or policy routing.  Do all the PE router lo0's have to be 
advertised into TDP/LDP for MPLS-VPN tag switching to work?

> Ack, but only for destinations not known via BGP (as Robert pointed out,
> if ipv4 and vpnv4 also use the same next-hop, both will be
> label-switched..

How/why would traffic to bgp learned non vpnv4 prefixes be label-switched 
if tags for those prefixes were not advertised?

----------------------------------------------------------------------
  Jon Lewis                   |  I route
  Senior Network Engineer     |  therefore you are
  Atlantic Net                | 
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