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New Member

Ping OK, Telnet fail, but Telnet from adjacent router OK

We have 2 3600 routers in remote which connect to our local 3600 router. This week found the strange phenomena: these 2 routers can be pinged from local network, but can not be telnet.

Only telnet the local router first, then telnet to these 2 routers OK. Anyone has any idea? thanks!

6 REPLIES
Cisco Employee

Re: Ping OK, Telnet fail, but Telnet from adjacent router OK

Access-list or Access-group

Re: Ping OK, Telnet fail, but Telnet from adjacent router OK

Any access-class applied?

New Member

Re: Ping OK, Telnet fail, but Telnet from adjacent router OK

No any access-group limitation. 2 weeks before they could be accessed from local PC. But now it can only be pinged.

Cisco Employee

Re: Ping OK, Telnet fail, but Telnet from adjacent router OK

try a 'debug telnet' and 'debug ip tcp packet'

New Member

Re: Ping OK, Telnet fail, but Telnet from adjacent router OK

My experience w/ 'debug ip tcp packet' is the same as 'debug all'. You may want to be careful if this is a production router.

Try turning off cef. That has bitten me several times in the past with similar symptoms.

New Member

Re: Ping OK, Telnet fail, but Telnet from adjacent router OK

I've tried the debug, but have not seen any packet to the remote router though I can ping it. Then use Sniffer, found no packet went out of this PC. The PC has Solarwinds installed, maybe there is some relation. Need further investigation.

The PC can telnet to local ethernet port of local router, but no any remote router can be telneted. the PC can ping them.

The other PCs which use the same gateway of the PC can telnet local and remote routers.

Some strange.

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