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Metro Routing

Unanswered Question
Jun 16th, 2006
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pls can anybody help. we have three routers here. The core router (7200)is responsible for connectivity to clients on our metro network. it has a DRAM of 96M and flash memory of 16M. Natting was done on this core router for internet connectivity for clients. A 2611 router was connected directly to a tier one provider . Caching was also done on the 3rd router which has an interface to the two other routers

The show processes cpu on the 7200 router reveals close to 100%. Each time the memory goes high, the whole network goes down. and the router has to be restarted at those period.

Can sommebody please suggest a way out of this problem.


Gabriel Oyeyemi.

Network Engineer.

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Overall Rating: 4.5 (2 ratings)
globalnettech Sun, 06/18/2006 - 06:01
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Hello Gabriel,

can you post the configuration of your core router, as well as the output of 'show proc cpu' ? I guess it would be useful to see which process is causing the high CPU. Since there are numerous bugs related to high CPU as well, can you also post the output of 'show version' ?

One thing that comes to mind when troubleshooting CPU utilization is CEF, do you have the enabled (with the global command 'ip cef')?



gabrieloyeyemi Mon, 06/19/2006 - 09:33
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Thanks so much for your help. I actually did a show processes cpu and dicovered that the internet traffic was using a lot of cpu because we did a lot of dynamic NAT config. on the core routers. What i did eventually to resolve the problem was to separate internet traffic from the data traffic for the MAN network. also i separated my local LAN from the clients network. Before now both our local LAN and the clients network has been on the same physical interface, they were only separated using sub-interface. Separating them therefore allowed me to apply the relevant access-list to the inbound and outbound interface connected to clients.

This made the CPU utilisation to return back to normal.

Thanks so much for your suggestion which actually guided me as to know exactly what to do.

Thanks so much.



gabrieloyeyemi Tue, 06/20/2006 - 07:24
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Please i also have another issue. I have some clients

playing a lot of music from the internet thereby occupying all the bandwidth allocated to them, and they keep complaining of slow internet access.

How can i possibly block music either on the clients' router or on my core router.

Pls your positive response will be a big relief to me.


romccallum Wed, 07/05/2006 - 05:40
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if you dont know the protocol number that the application is using then use a combination of netflow and nbar to find out. Once you have the protocol number then you can rate-limit based on this.

jackyoung Sun, 07/23/2006 - 18:45
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And block or limit those traffic from the entry. e.g. if they poll the traffic from Internet then block or limit it at the Internet direct connected router then it can save the WAN bandwidth.

Or you can try to discover which music site that they are visiting and simple block those site then it is fine. But you may need to add the filter by periodically.

The most important is to define a clear operation policy to the user that it is (or may) not allowed to access those music / multimedia / non-busniess related sites in office..... Otherwise, it is neverending war.

Hope this helps.

gabrieloyeyemi Mon, 07/24/2006 - 00:26
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Thanks so much.

I have limited the bandwidth allocated to such traffic to 1k on the packet shaper.



jackyoung Mon, 07/24/2006 - 01:04
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You're welcome. It is good that block it externally and save the router processing resource. Do you think the user will complain the slow connection to those music site ? ;)


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