Ali -
Vernon's comments in his previous response were essentially correct and I
was imprecise. If the failure of R4 takes down the link between R3 and R4 -
the failure of the link will be immediately detected at R3 by virtually
every protocol (except static routing) and propagate quickly. If the link is
something like a shared Ethernet, then older routing protocols (e.g.,
) may take some time to recover because they lack a "heartbeat" mechanism,
and can only detect the failure by the absence of periodic updates from the
neighbor.
So the answer, as always, is "it depends" :)
/Michel
-----Original Message-----
From: Ali Boudani [mailto:aboudani(_at_)irisa(_dot_)fr]
Sent: Wednesday, February 13, 2002 6:49 AM
To: ietf(_at_)ietf(_dot_)org
Subject: Simple question
If we have the following figure:
R1---------R2---------R3---------R4 where R1 to R4 are unicast routers.
R1 is sending packets to R4. If R4 goes down, when R1 will detect this??
Before sending packets or after?