The MPLS WG Archive

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

Jia Hong wrote:
> 
>         I have one more doubt related to hello message. If there are
> say 3 interfaces between two nodes then the hellos should be
> transmitted on all the 3 interfaces. This means the hello message
> are used to detect the interface failures and not the node failure
> in case there are multiple parallel point to point links between two
> nodes.

What protocol are you talking about?

In LDP, Hellos are transmitted on every interface, and work as you
describe - detecting link failures.

In RSVP, if all the interfaces are numbered, Hellos will be sent on each
interface.  If there are unnumbered interfaces, however, Hellos will
only be sent on one interface (per neighbor, of course).  The RSVP-TE
document describes the details of how this is supposed to work.

-- David