interface shutdown

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Jun 8th, 2007
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Hi all,

I have two routers, Router-A directly connected Router-B if I given shutdown to an interface in Router-A which is going to connect Router-B, now what will happen, if I issue show interface on Router-B whats output would I see on the interface that is connected Router-A.



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jaffer_sathik2010 Fri, 06/08/2007 - 03:03
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Interface status will be UP DOWM

That is, Serial will be 'up' but line protocol will be 'down'.


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Anand Narayana Fri, 06/08/2007 - 03:08
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if you issue command "show interface serial 0/0/0" you can find the status on the very 1st line as "Serial0/0/1 is up, line protocol is down"

if both routers are up then "Serial0/0/1 is up, line protocol is up"

ilnaiduccna Fri, 06/08/2007 - 03:52
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Hi Anand,

Thanks ur early reply all

The line protocol would be down it's ok, and the interface would be down. The first part of the result will indicate whether the interface hardware is active r not am i right.

Now if I put it administratively down which is going to connect Router-B now what will be.



Anand Narayana Fri, 06/08/2007 - 05:08
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you will get the message like this..........

"Serial 0/0 is administratively down, line protocol is down"

CSCO10892433 Fri, 06/08/2007 - 20:26
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Hi, ilnaiduccna

If these routers are connected directly by a back-to-back DTE-DCE cable (just like we do in the lab), when you shotdown the interface in one end, the other end will goto down/down state because it cannot detect DCD carrier and layer2 keepalive message form the other end.

If these routers are connected by a pairs of DSU/CSUs (like in the real life senario), shutting down the interface in one end will cause the other end goto up/down state because it will not receive layer2 keepalive from the other end, but it still can receive the DCD signal from CSU/DSU.




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