The MPLS WG Archive

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

Feng, Mark wrote:
> Also keep in mind that, with the interfaces "proposed" in RFC2205, the
> sender address is used to force the message to go out at a particular
> interface, overwriting the routing module. Obviously, this is implementation
> dependent. Like David mentioned in the previous message, there is no
> "standard" way of setting the sender address.

I don't think this is correct.  Without explicit routes (which is how 
RFC 2205 is defined), Path messages must always follow the routing 
table's route to the session address.

The interfaces in section 3.11.1 of RFC 2205 are _NOT_ describing rules 
of forming packets.  It is proposing one possible API that can be used 
by applications to make requests of an RSVP protocol stack.

The interface selection rule in the SENDER() call is simply to bind a 
connection to an interface, much like the bind() call does on the server 
side of an ordinary socket.  Note also that it may be left undefined - 
much like INADDR_ANY can be used in bind().  The implementation is no 
required to blindly copy this value into the SENDER_TEMPLATE object of 
the Path message.

Section 3.11 of RFC 2205 (and all of RFC 2209) should be seen only as 
informational.  They are defining one possible API/implementation, but 
are not defining the only possible one.  Depending on your switch's 
overall software architecture, that design may be pretty bad for you.

-- David