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New Member

Troubleshooting with PING

Good Afternoon,

Simple troubleshooting question but I have gotten confused. I am trying to ping the ethernet interface on the router across the WAN. We had a storm in the area and lost the switch trying to confirm the router eithernet interface is good.

I can ping the serial interface on the router but not the ethernet interface. Since the switch is offline the ethernet interface is 'line protocol is down'. But I thought I would be able to still ping the interface?

Am I wrong? When there is no activity from the switch I cannot ping the interface through the WAN interface?

Thanks,

Pete

  • Other Network Infrastructure Subjects
2 REPLIES
New Member

Re: Troubleshooting with PING

Sorry Pete, unfortunately, if the protocol is down for an interface you will not be able to ping it. I have run into it before when troubleshooting T-1's on serial interfaces. If a circuit goes down I usually know the IP address of one of the sides of the circuit, unfortunately, that doesnt help me because I cannot telnet to either side of the T-1 serial interfaces as long as the circuit is down. The workaround is to either telnet (or ping in your case) to another working interface on the router. The other, and best practice, workaround is to assign loopback addresses to all your routers so you dont have to worry about interfaces going down. Pinging a telnet address will tell you if you can get to ANY interface on the router.

Hope that helps!

Re: Troubleshooting with PING

You can't ping an interface that is line down. You can put an ethernet interface as always up/up if you want with the interface command "no keep".

Steve

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