The MPLS WG Archive

[Ping Pan <pingpan@juniper.net>]

George Swallow wrote:
> 
> Ping -
> 
> Totally agree that something along these lines is necessary.
> 

George,

Thanks.

> Some comments:
> 
> The draft should say explicitly that the Echo and LSP-Ping messages
> are sent down the LSPs.
>

OK.
 
> If you have multiple LSPs between two nodes then it may be hard to
> determine that an LSP has failed, since you will get Echo-Reply
> messages from the other tunnels.  The draft should recommend use of
> the Identifier field in the Echo message in this case.
>

When using LSP-ping, as we mentioned in 5.1, the echo message should
have enough information to identify an LSP. That implies, the message
will have RSVP Session and Sender-Template objects. I will articulate it
more explicitly soon.

> You don't give a message type for the LSP-ping.  Were you thinking of
> a new message?  Perhaps the Notify message could be used?
>

For LSP-ping messages, the echo packets are encapsulated in UDP with a
well-known port number. At the egress, the LSR picks up the echo by
"listening" to the UDP port, and replies them back in Resv. I didn't
consider the Notify message.... Let me think about it.
 
> There needs to be a means of clearing the LSP-echo object from the
> RESV message.  (So that the test can be repeated at a later point).
> I would simply add a timer that gets set when you first insert the
> LSP-ping object in the RESV message and renewed each time you receive
> a subsequent LSP-ping message.  Once the messages cease, the timer
> will fire and you then send a RESV message without the LSP-ping
> object.
> 

Interesting. How do I inform the egress about the timer? In the first
LSP-ping message, or Path? And how do I turn it off?


> You might add a note to the intermediate node processing that says
> the text in only there to emphasize good practice.  It doen't really
> impose any new requirements.
> 

OK. I will.


> ...George
> 
> ==================================================================
> George Swallow       Cisco Systems                   (978) 244-8143
>                      250 Apollo Drive
>                      Chelmsford, Ma 01824

Very helpful. Thanks!

- Ping