2901 router telnet sort of working...

[aBs0lut30]

I ran into an odd issue I have never seen before...

I've got a 2901 router in a remote office that terminates a PRI into our call manager.

Got a call from the site saying they couldn't call out... I tried to call in and couldn't either.

I tried to telnet to the router, the session comes up and gives me the login prompt, but won't take any input.

Try to type in my username but it's not accepting any text.

I had them go power off the router and bring it back up. Now the phones work, but telnet is still messed up.

Just as before, I can connect and bring up a session, but nothing I hit on the keyboard does a thing.

After about 15 seconds, the connection get's reset.

Anyone ever seen anything like that before? Or have any suggestions short of going out there and sticking a console cable on it?

[Richard Burts]

It does seem quite strange symptoms. I am guessing that the issue about not being able to call in or call out is different from the issue with telnet, especially since reboot seems to have fixed the problem about calling but not with telnet.

So you initiate the telnet, get a prompt for user name, but are not able to type any input. Is that correct? Am I correct in assuming that telnet has worked successfully in the past? Have you tried telnet from a different device? Have you tried SSH instead of telnet? Is it possible to establish a connection (RDP or something similar) to a device inside that network and then telnet to the router from an inside address?

Ultimately you may need a console cable.

HTH

Rick

[aBs0lut30]

Yeah, I'm somewhat baffled by this as well.

I don't have SSH setup on that particular router, so can't really try that.

I will try a connection from a local PC in that office and see what I get.

But yes, that's the weird thing (using putty...) open the telnet session and it come's right up, give's the the login text and prompts for username, no keyboard input at all will echo characters back. 

Was working earlier in the week as I connected in to reboot it during some call manager maintenance we were doing Monday night.

So, sometime between then and this morning, something very strange happened.

I'll try a local connection and report back, but I suspect it will be the same result.

[Georg Pauwen]

Hello,

it might be worth trying TeraTerm, maybe the problem is with the emulator:

https://tera-term.en.lo4d.com/windows

You also could try to specify a source interface (create a loopback and use that) and a retransmit timeout:

2901(config)#ip telnet source-interface Loopback1

2901(config)#ip telnet timeout retransmit 1

[Richard Burts]

Am I correct in understanding that this is the sequence of events:

- in the past this router was working. calls could be established and telnet from remote site worked successfully.

- within the last week there was maintenance on call manager which appeared to be successful. calls could be established and telnet was successful.

- you received information about a problem in which calls could not be established.

- in troubleshooting the call establishment problem you discovered a problem in establishing a telnet session.

- the router was rebooted.

- after the reboot the problem with call establishment was solved but the problem with telnet continues.

I had originally wondered if both symptoms (call establishment and telnet) might be due to a single problem. But based on this series of events I believe that the telnet problem is separate from the call establishment problem. I encourage you to try the alternatives that have been suggested (try a different terminal emulator, try to telnet from a device inside the network, etc) but I am not optimistic that they will solve the issue. I am guessing that it will take a console connection to solve this.

It occurs to me to ask whether this router is sending log messages to a syslog server or whether there is any type of monitoring that might have reported some type of issue from this router?

HTH

Rick

[klenkovk]

I have faced this problem too. I tried to get access to remote device console via 2901 aux port. I have fixed problem, applying

line aux0

speed 115200

[liviu.gheorghe]

How is the router accessed remotely? Does it have a dedicated WAN connection or you are using part of the PRI for the WAN connection? I'm thinking about two possible causes:

1. WAN congestion - in which case can you provide a show interface output of your WAN interface

2. Router CPU resources - in which case a show proc cpu / show proc cpu history will rule this out

HTH