MPLS TE

Fri Nov 4 16:49:31 UTC 2011

Hello Mike,
What exactly do you mean by primary and backup please?
As the tunnel "mpls traffic-eng priority" cmd simply only specifies the setup and hold priorities 
(you'd use those when there are tunnels carrying low priority traffic filling up the available TE BW -and you need to setup a tunnel carrying voice through that link -because the primary link failed -the higher setup priority of the voice tunnel would knock down some of the scavenger tunnels with lower hold priority)

Now I'm not sure but I guess you can't have one tunnel act as backup for a specific te-tunnel
Though you can configure a te-tunnel to act as a backup for a link

Since one of your tunnels is dynamic it can be re-established around the failed link

Though which tunnel is going to be used to forward traffic is based on how you instruct the trafic to use one of the tunnes as primary path

adam

-----Original Message-----
From: harbor235 [mailto:harbor235 at gmail.com] 
Sent: Friday, November 04, 2011 5:10 PM
To: NANOG list
Subject: MPLS TE

TE lab testing flushing out how TE works, configured a primary and backup
tunnel between PEs, both directions.
Primary is dynamic and backup is explicit, initially priorities were the
same, I then choose
to make one tunnel preferred over the other adjusting the priorities, I
choose the tunnel that was backup
to become primary to watch the traffic shift. (primary path was P1-P2-P3,
backup path P1-P3). However,
the traffic did not shift, a manual shut on a P3-P2 interface made the
traffic shift, reintroduction
kept the traffic on P1-P3,  then a "mpls traffic reoptimize" moved the
traffic back to P1-P2-P3.

Obviously the preferred MPLS tunnel is still  P1-P2-P3 even though I
configured "tunnel mpls traffic-eng priority 1 1"
on P1-P3 and "tunnel mpls traffic-eng priority 7 7" on P1-P2-P3. What am I
missing here?

My setup:

CE-----PE-----P1----------P3-------PE----CE
                     \          /
                      \        /
                          P2

Mike