I've got a 2801 sitting here.
When I 'sh int', both FastEth interfaces show "interface is up, line protocol is down".
The thing is, nothing is plugged into either one... Shouldn't they both be down/down due to physical issue?
Solved! Go to Solution.
Actually for Ethernet/FastEthernet interfaces it is normal for them to show as up/down when nothing is plugged in. Is it just that it is different from what you expected, or is there some problem involved with this?
If you do a shutdown on the interface it will show as admin down, which is not quite the same as down/down.
Thanks for the quick replies.
With nothing plugged in, I was expecting down/down....
When will an interface show down/down (not admin down/down)???
I thought that the first up/down was the physical layer status, and the line protocol was the layer 2 status...
What you describe (interface up/down is the physical layer and line protocol up/down is the layer 2 status) is the case for most serial interfaces. It is not the case for Ethernet/FastEthernet interfaces. I am not sure what it would take for an Ethernet/FastEthernet to show down/down.
I am glad that my information has been helpful. Thank you for using the rating system to indicate that your question was resolved (and thanks for the rating). It makes the forum more useful when people can read a question and can know that they will read responses which did resolve the question.
The forum is an excellent place to learn about Cisco networking. I encourage you to continue your participation in the forum.
This is interesting conversation.
On the other hand, if you disable "keepalive" in the router ethernet interface, both physical and protocol will show up/up