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Cisco 2600 router - basic ping questions

Posted on 2004-04-30
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Last Modified: 2013-11-29
I must've forgot how to setup a router.  My router has an ethernet port (E0) and two serial ports (S0 & S1) respectively.

IP's are configed and interfaces are up and I've set the bandwidth on S0 to 64000.

I can't ping from E0 to S0.  I use an extended ping which the target is the S0 IP from the source which is E0.

I get a strange response:   U.U.U.U

I've never seen U's before.  I've seen ! and . but never U's.

I've looked in the Cicso command reference files on the website and that response is not there.  In fact, it doesn't even say what a ! or a period means.

My questions are:
-What does a U mean?
-Is it the same as a period?
-What are the critical settings I need to get a serial interface working?

Martin
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Question by:atenciom
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mikebernhardt earned 125 total points
ID: 10965027
The U means that the network is unreachable, whereas . means that the host is unreachable.

If you type "show ip interface brief" do you see the serial interface as up/up, up/down or down/down? Unless you've got a live link on the serial link it won't be up/up. Without up/up the network on that interface won't be up either, hence the network is unreachable.

You don't need a bandwidth statement on the serial interface, that is only used to customize routing metrics in some routing protocols. You might try "no keepalive" on the serial interface for now. That *might* bring it up, I'm not sure and can't try it right now.

If you have a DCE/DTE cable (I'm assuming you have a 2500 series router) you can configure a clock rate on your serial interface and simply cable it to the 2nd serial interface, no-shut the 2nd interface and that will bring up both of them. You don't need an IP address on the 2nd interface for this.
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