[c-nsp] Routing design question

[Lincoln Dale (ltd)]

> > Will auto-neg signal one-way fiber failures (after the link has already
> > been brought up and autoneg'ed successfully)?  Never tried that.
> 
> Yes, it works much better (and faster) than UDLD. The endpoint which
> has lost receive fiber will immediately signal "RemoteFault" to the
> other end and line protocol will go down on both sides within miliseconds.

the primary intent of UDLD is detection of mis-cabling at layer-2.
e.g. lets say you had three devices, cabled with tx/rx in a triangle.

the link may well come up at layer-1 but it sure will do bad bad things at layer-2 particularly with protocols like spanning-tree!

UDLD will detect that, autoneg won't.

the recommendation would be to use both autoneg (layer-1) and UDLD (layer-2).


cheers,

lincoln.