Hi Greg,
I believe this comment was in context of S-BFD for VCCV.
>From what I understand, the scenario which S-BFD for VCCV is looked into is
the case where one end of the PW has very constrained resources. Using the
classical BFD will require such devices to maintain a session object per PW,
as opposed to S-BFD which only requires one reflector session.
Your comment about why not send BFD echo packets over the PW? Sending a
probe (BFD echo) with IP destination having the sender address, across
multiple physical hops, always has the danger of the probe packet still
coming back to the sender despite issues. Yes this is more likely on LSPs
like LDP, RSVP (and less likely on PW) but it is possible that PW label gets
exposed "somewhere" and that label value happens to match a different LSP,
picking up traversal to a different node.
Then there's the desire for return packets to come back on the reverse
direction of the forward PW. Whether we go with S-BFD for VCCV or BFD echo,
this (i.e., reflector bouncing back packets on the reverse PW) is a change
that needs to be made/standardized.
So to me, S-BFD for VCCV makes sense.
Thanks!
-Nobo
From: Rtg-bfd [mailto:[email protected]] On Behalf Of Gregory Mirsky
Sent: March-23-15 1:54 PM
To: [email protected]
Subject: BFD Echo format
Dear All,
I stand corrected, BFD Echo format is not defined in the RFC 5880 but there
requirement suggesting that BFD Discriminator MAY be used to demux Echo
replies:
The payload of a BFD Echo packet is a local matter, since only the
sending system ever processes the content. The only requirement is
that sufficient information is included to demultiplex the received
packet to the correct BFD session after it is looped back to the
sender. The contents are otherwise outside the scope of this
specification.
Regards,
Greg
