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New Member

1811 Router causing internet 'slowness'


I have a 1811 router that seems to be the cause of repeated failures in web requests. Users are complaining of having to refresh pages multiple times to connect. Once restarted, the traffic flows smoothly again.

How can I monitor the router to detect the cause of this in order to be sure that it is the problem?



Re: 1811 Router causing internet 'slowness'

hello Charlie,

could you give us more information on this issue?

what kind of services is this router doing? for intance Are you doing nat? what kind of routing protocol? how about cpu process utilization? memory? is there any interface errors? packets discards? buffer overflows?


New Member

Re: 1811 Router causing internet 'slowness'


The router provides:



VPN (Site to Site)

for the internal private network

What is the best way to monitor the router from a CLI?

New Member

Re: 1811 Router causing internet 'slowness'

Still experiencing this issue.

Can you advise how I can see the various things you metioned above:

-cpu process utilization


-interface errors

-packet discards

-buffer overflows

Id like to be able to check these items when 1.) Traffic is flowing and 2.) When traffic is NOT flowing. How do I monitor these items from CLI?

Also, the strange part of the issue is that the VPN tunnel to the remote email server is fine and VOIP traffic seems to be unaffected, but http and https requests require multiple refreshes to get a page to load.

Ive attached the output from a show running-config.

New Member

Re: 1811 Router causing internet 'slowness'

hi ,

1. Check if your Internet link is choking or not ?

2. check for viruses on lan ?

Cisco Employee

Re: 1811 Router causing internet 'slowness'

Do you have any NMS tools such as IPM that you could use to monitor response time for HTTP traffic?

New Member

Re: 1811 Router causing internet 'slowness'


You could try "show ip nat trans" to see the nat translation table. If it is very long when the web pages are slow, try clearing the nat translation table using the "clear ip nat trans *" command.

If that corrects the problem, you might want to add the following to your nat config:

ip nat translation tcp-timeout 7200

Hope this helps.

New Member

Re: 1811 Router causing internet 'slowness'


Im not sure what you mean by 'very long'. Is there a particular metric I can monitor that will help me confirm the 'slowness' mentioned above? Id prefer to do this at CLI, but if I have to use something like SDM, I can do that as well.

The symptom that the users are experiencing is that http and https requests need to be made multiple times in order for a page to fully load. What metrics or statistics should I be looking at to confirm that the problem exists in the router or elsewhere?

New Member

Re: 1811 Router causing internet 'slowness'

By 'very long', I meant pages and pages of entries in the translation table.

I am unaware of any metric that monitors 'slowness'. We have experienced Internet slowness because the routers nat table is full and the router must clear an entry before a new one can be created. (processor intensive and slow) This was caused by the old entries never timing out.

We determined this by clearing the nat table and discovering the slowness went away. We then added the timeout statement so the table never filled up.

If clearing the table using the cli does not help, then you must be experiencing a different problem then we did.

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