The MPLS WG Archive

[Shahram Davari <Shahram_Davari@pmc-sierra.com>]

Curtis,



> > > My interpretation is push both labels.  Both start at TTL=1.
> > > Increment top, then next label.  If they both terminate 
> at the same
> > > egress LSR (normal for BGP VPN) then bottom TTL never gets past 1.
> > 
> > What do you do for pinging the inner LSP?
> 
> For ping mode, set all the labels that you want tested to TTL=255 and
> send.  If there are any hops after the top, the packet gets delivered
> to the egress of the label you want tested.
> 
> Did you mean traceroute?


No I meant ping. But I am not satisfied with your answer. Let's assume
we have a PWE3 connection, and the user packets are sent with 2 labels (A & B).
Label A is the PW label and label B is the transport label. The egress LSR checks the transport label and terminates it and forwards the packet based on the
PW label. It never checks the S-bit. If LSP-ping has the same label stack (A&B)
then the LSP-ping will be delivered to the customer. Don't you think so?

 If the LSR at TTL=4 swaps label X for Y it
> puts Y in the Downstream Mapping TLV in the echo reply.  T


Here is my point. How do you put the Downstream mapping TLV in the
RESV message if the return path is via control-plane?

-Shahram