[c-nsp] forced path MPLS tunnel question

[Vitkovsky, Adam]

Hi

Question #1:
Yes you can use "verbatim" keyword in the path option
-router will attempt to build the tunnel without checking the te-lsdb

Question #2
-before the tunnel is build, router will check the te-lsdb to see whether the path specified (explicit or dynamic) has sufficient parameters for the tunnel to be established
That's why the router needs to know about all links in the network and all their parameters -thus link-state protocols like is-is or ospf are used with mpls-te


adam

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Gert Doering
Sent: Tuesday, January 17, 2012 11:05 AM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] forced path MPLS tunnel question

Hi,

I'm currently considering options to better monitor the MPLS bits of our
network - specifically, make sure that MPLS *forwarding* works, without
having to rely on end systems noticing EoMPLS links going "black hole"
or L3 VRFs going down.

One of the reasons for MPLS forwarding to break could be "ethernet circuit
bought from $3rd_party, their equipment failing to properly forward all
different ethernet types -> IPv4 works, MPLS fails" - happened to a colleague 
recently, which got me thinking...

The way I thought this could be done is to setup a MPLS tunnel with a 
static path, crossing all "major" links (this is a small network, so the 
tunnel just needs to go through 6 routers or so to visit all backbone 
MPLS links), and then send ping probes down that tunnel.  MPLS forwarding
breaks -> ping breaks -> operator goes investigating.

Now, the documentation that I found ties this to 

  "tunnel mode mpls traffic-eng"

and *this* seems to require OSPF or ISIS being used as an IGP - which 
we don't have, right now.

(Platform is 6500/Sup720, IOS 12.2SXH/SXI)


So, Question #1:

 - is there a way to setup a static MPLS tunnel/LSP "take *this* link and
   then *that* link and then go *there*" without OSPF or ISIS?

Question #2:

 - what is happening "behind the scenes" to make static(!) paths require
   OSPF / ISIS?  I can understand that auto-te needs the necessary metrics,
   but "basic MPLS" works fine with just BGP/LDP/EIGRP...

(And yes, I could move everything over to OSPF, it's just that I want 
to understand the reasons for it)

thanks,

gert
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Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de