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

[Jon Lewis]

On Wed, 26 Oct 2005, Oliver Boehmer (oboehmer) wrote:

>> routes in question are not in our iBGP.  They're being learned via
>> OSPF.
>
> Well, then your issue can be addressed by restricting label
> advertisements to BGP next-hops (i.e. PE loopbacks)? Then your
> OSPF-learnt routes won't be label-switched, voila.

Using the no tag-switching advertise tags, and tag-switching advertise 
tags for commands on just two of our routers, I got this working such that 
plain IP packets are routed (between the two routers) now instead of 
tag-switched, which allows me to staticly route this customer's VOIP 
server down a dedicated path.

BTW, upgrading from 12.2S to 12.3M did get tagged packets over MLPPP cef 
switched instead of process switched, but it seems to have introduced a 
new problem.  Under either 12.2S or 12.3M, the Mu1 interface has had 
issues with output drops even though we rarely got above 50% utilization. 
Though I know cisco recommends against it, I was able to nearly get rid of 
them under 12.2S by increasing the output hold queue.  It just seemed kind 
of wrong that as individual T1's there should be output queues of 40 per 
interface, but as a MLPPP interface of 5-6 T1s, there should be a single 
output queue of 40.  Under 12.3(16), increasing the Mu1 output hold queue 
doesn't seem to help as much.  Without any increase, I was seeing around 
0.5% packet drops while there was only about 1mbps going out the Mu1. 
With a hold queue of 300, the output drops are down to under 0.05% with 
about 3.5mbps going out the Mu1 at the moment.  I played around with 
fair-queue/no fair-queue and tried enabling fragmentation.  None of these 
made a difference.  I may end up just going back to cef per-packet now 
that we can keep the voice traffic on its own circuit.

Apparently as a result of the tag-switching advertise changes, I'm now 
seeing messages like this from time to time on the two changed routers.

Oct 27 08:16:14: %TIB-5-WDRAWTAG: 209.208.109.128/255.255.255.128, tag 
814; Withdrawn tag record has timed out.

Nobody's complaining yet, so I don't think its a problem.

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