[j-nsp] traceroute in mpls vpn's not showing P hops

[Aaron Gould]

I know that this is a known thing with mpls networks, and there are a few
tricks with no decrement ttl or no propagate ttl to cause P cloud to be
completely invisible. but is there a way to do the opposite?...that is, is
there a way to cause the P routers to be seen on traceroute ?  I understand
that ttl expired in transit messages need to be able to be sent back to the
CE that sent the low-ttl packets to begin with and since p router probably
won't have the vrf-specific routes of that ce, then, well.. I guess I'm
wondering if there's some trick command that allows the p router to send
back the ttl-expired-in-transit messages simply via the same mpls label
values via the lsp that they arrived on. or whoever it would work. ?

 

----- trace initiated be CE r1

 

r1 at lab-mx104:r1> traceroute 1.1.10.2 wait 1

traceroute to 1.1.10.2 (1.1.10.2), 30 hops max, 40 byte packets

1  1.1.0.2 (1.1.0.2)  0.539 ms  0.646 ms  0.472 ms               <---- PE 

 2  * * *
<---- P

3  * * *
<---- P

4  * * *
<---- P

5  * * *
<---- P

6  * * *
<---- P

7  1.1.10.1 (1.1.10.1)  0.611 ms  0.565 ms  0.534 ms           <---- PE

8  1.1.10.2 (1.1.10.2)  0.569 ms  0.616 ms  0.700 ms           <---- CE

 

- Aaron Gould