Keepalive on Ethernet interface
Now... this is interesting.
I've been digging for a little bit now looking for some clarification on the mechanics of this protocol and found that it is called the "Configuration Test Protocol." It is not part of the IEEE 802.3 standard, but it is part of the original Ethernet Standard. I found a copy of the CTP specification here:
So I wonder if you need to disable keepalives on a Cisco router that is attached to a non-Cisco switch or other ethernet device that does not support CTP? Or is the router not really looking for a reply on the wire? I wonder if the controller on the router is looping back this frame locally and that is what the router is looking for?
On the other hand, I know from personal experience that some media converters will supply a carrier toward the router even if the distant end device is down, and in those cases we see the ethernet is up, line protocol down. This would seem to indicate the router is indeed looking for a reply back on the wire.
Anyone else have any ideas on this? Perhaps some sniffer traces showing replies coming back to the router from the opposite direction?
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- Show quoted text - Derick W
read more and respond »Posted 5 years ago by angry_engineer in Cisco Systems
