On 01/07/2013 06:32 AM, h bagade wrote:
Can I conclude from all discussions above that the ethernet protocol
support a feature named "dying gasp" which inform the other end that it is
going to shutdown? It seems that it works when we intentionally try to
shutdown an interface but when there is a failure on layer2 connection it
couldn't help?!
No. The spec contains this feature, but virtually nothing supports it.
Link detection on ethernet is actually a slightly subtle area, but if:
1. You have autoneg enabled, and
2. The devices are *DIRECTLY* connected
...you can be sure it will work IF THE LINK GOES DOWN.
There's a lot of confusion in your emails, but what I think you're
asking is:
if you connect two Cisco devices, how is one able to detect the other
doing "shutdown"?
...the answer is that on a Cisco, "shutdown" actually disables the
physical layer, and the other Cisco detects this. In your case, the
other device (BSD) is not doing this, so this doesn't happen.
There's no magic - if the light/electricity goes away, the Cisco will
see "line down". If it doesn't, it won't.
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