2621-Router hang after internet upgrade

Unanswered Question
Nov 14th, 2008

2621XM-Router hang some time(It was working fine from 4 days)after we have upgraded the internet leased line from 1MB to 4MB.whenever the internet line is getting struck inbetween we need to restart the router OR service providers modem.

suggest me the right solution for this ASAP.

Thanks in Advance

I have this problem too.
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Giuseppe Larosa Sat, 11/15/2008 - 01:28

Hello Aejaz,

>> whenever the internet line is getting struck inbetween we need to restart the router OR service providers modem

this doesn't look like a router crash but a problem on the WAN link.

to try to restart a serial line you can try to make a shut / no shut of the serial interface on the router.

If there are cases where resetting the service provider modem you fix it this is not a problem on the router.

You should provide some more information: what type of network module is the serial interface part of ?

I'm not sure all network modules support a speed of 4 Mbps over a single serial port.

your IOS release and the interesting parts of your configuration.

If you have some heavy features like ip inspect (CBAC) applied this can increase the cpu usage, but the fact that resetting modem fixes make to think to a Layer1 problem on the link.

post also a show interface serial x/y to see if there are any error counters that are increasing over time

Hope to help


aejaz.armi Sat, 11/15/2008 - 21:58

Internet link is with ethernet(IPMPLS-4MB) and the problem is resolving by restarting the router.

kindly provide the appropriate solution.


Giuseppe Larosa Sun, 11/16/2008 - 04:30

Hello Aejaz,

some more information is needed in order to get better help.

provide a filtered version of your config, to understand what features are enabled.

provide also a

sh proc cpu sorted 1min

sh proc mem | inc Free

sh ip nat translations

Clearly there has been an increase in traffic volume to/from the internet with the new setup.

We need to understand what makes the router to hang.

A possible candidate is NAT but you may have other features like ip inspect using resources on the router.

Hope to help



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