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What could be the reason a cisco gigabitethernet interface gives status down protocol down and doesn't change this while doing a "no keepalive" on the interface? (nothing connected to the interface).

Interface                  IP-Address      OK? Method Status           Protocol   
GigabitEthernet0/0 YES NVRAM down down

Normaly this would give an "up down" status even if nothing is connected.

Any ideas? I want to use the "no keepalive" for testing purposes (when nothing is connected).

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Is the port shutdown? – Dan Jul 18 '12 at 13:56
Wait, does "nothing connected to the interface" mean that there's no cable in the port? If so, that's why. Plug something in to it and see if that doesn't change the status. – HopelessN00b Jul 18 '12 at 14:12
Agreed, by plugging something in, the status goes to "up up". But when testing on 2 locations, it's preferable to do this remotely. A "no keepalive" should tell the router that no keepalive packets are needed to give an "up" status. – Bulki Jul 18 '12 at 14:21
How do you hope to get an initial 'up' without plugging it in? – Sirch Jul 18 '12 at 14:27
What model? I'm pretty sure their switches and most of their routers don't bring it "UP" anymore with the no keepalive option like they used to. – TheCleaner Jul 18 '12 at 15:22
up vote 4 down vote accepted

Issue the shutdown first, then issue the "no keepalive" command, then bring the interface back up. It should show up/up at this point and hold that state indefinitely (for a GE, anyhow). Turning keepalive tracking off while the interface has already marked itself down isn't going to bring it up.

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using the no shutdown and no keepalive after still gives a "down down" result. – Bulki Jul 19 '12 at 6:33
This should work - I even verified it on a 7200 I had lying around. What model of router is in use and can you post a (sanitized) copy of the interface's config stanza? – rnxrx Jul 20 '12 at 1:18
A Cisco Router 1921, apparently Cisco implemented it this way in these routers. The only solution is to use loopbacks instead. – Bulki Jul 23 '12 at 10:23

So the interface is down and the line protocol is down.

Is the interface administratively down? Use the no shutdown config command to enable the interface. (Also make sure a good cable it plugged in)

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No shut and no keepalive have been done on the interface. (otherwise it would say "administratively down" indeed) – Bulki Jul 18 '12 at 14:03
Then I'd seriously consider hardware/cable failure. – Sirch Jul 18 '12 at 14:05
I've tested further by connecting a device to the router. This time it says "up up" (is normal behavior), nothing wrong with the hardware. – Bulki Jul 18 '12 at 14:20
so, if you get up up, then what's the problem? – The Unix Janitor Jul 18 '12 at 15:39
The problem is that I can not test the connectivity without having a physical connection. This is possible with the "no keepalive" command normally, but in this case it didn't work, status remains on "down down". – Bulki Jul 19 '12 at 6:08

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