The MPLS WG Archive

[David Charlap <David.Charlap@marconi.com>]

Harish Kumtakar wrote:
> 
>    what i understood after reading RFC 2205 and 2209 is that, when a 
> node receives a PATH message it will store or update the info. contained 
> in the message into corresponding PATH state and then forwards the PATH 
> message (the message may be modified) to the next hop.

Actually, the outgoing message will always be different from the 
incoming message.  At the very least, the HOP object will be different.

It's misleading to think that a Path/Resv message is forwarded.  It is 
not.  It is intercepted and processed.  A new Path/Resv message may (or 
may not, depending on circumstances) be generated as a result of that 
processing.

>   my question is will that node stores the info that is modified by 
> it(in case the PATH message is modified) somewhere (i mean, in some 
> state?).

I'm not sure what you're asking here.

Every node must (at minimum) store everything from an incoming Path/Resv 
message.  It must compare subsequent messages with the stored data in 
order to determine if the subsequent message is a modification or a refresh.

What additional information it stores in order to generate and send any 
corresponding outgoing message is an implementation detail and is not 
specified by any standard.

-- David