1841-ADSL router not accessing some websites.

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Nov 28th, 2005
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I installed an integrated router 1841-ADSL at a customer. It appears to work fine intially but eventually its performance degrades and the customer is unable to reach some websites. If I do an ADSL high speed bandwidth test the speed is fine. I believe the problem is at the ISP, put they are saying everything is ok on their side. Is there a test or debug I can run on the router to prove that the problem is not the router?

I am using pppoe and the DSL bandwidth is 512kbps. The firewall service is enabled on the router.

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binoyjosephstanly Mon, 11/28/2005 - 20:25
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my dear friend

can you just post your config.

you have to check one thin g properly, your MTU size of ethernet port make it 1492 or 1452.

hope you are facing problems when you access https sites is it. do this and check the status.



briangardner Wed, 11/30/2005 - 13:38
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I've got basically the same problem you're encountering (see my post a couple before yours). Only difference is I don't have the firewall feature turned on, and after a while it gets down to can't get anywhere. I'm waiting on my smartnet agreement to go into effect, so can't call Cisco tech support yet. I'm really hoping somebody out there has an idea or direction we can take.


tcordier Thu, 12/01/2005 - 04:59
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Hi Wayne,

it would be helpful if you could paste the config of the router here.

Next to that, I can only suggest troubleshooting:

- can you ping the website your are having problems with?

- if not, can you ping the IP address of the website you are having problems with?

- if not, try to run debugging while you are trying to ping the website,

- if ping works, but browsing does not, you can issue a telnet 80 and see if you get a connect,

- if not, try to debug the connection while you are trying to connect,

- if you can ping the website, make sure you can ping with packetsize up to 1500 bytes.

- check if NAT (I suppose you have NAT) translations become active when you make a connection attempt. You can clear the NAT table, try to connect, then check the NAT table again to make sure.

The main idea is to find out on what layer we do have a problem.

HTH, Thomas

wdbrewster Fri, 12/02/2005 - 10:31
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Hi all,

So far the router is working ok since the ISP made some corrections on their side.

Thanks to all for your inputs.

However I have a VPN issue to resolve. There is Site "A" and Site "B". Site "B" has other remote sites Site "BA" and "BB", but the tunnel from Site A terminates on the router/fw (1841) on Site B. I am having trouble accessing servers at remote sites BA and BB from Site A via the tunnel.

I am also setting up VPN sites that require tunnels from dynamic sites, static sites and VPN clients using the 1841. I am using keyring profiles to make this work, but I am getting hell. When you get the static up the dynamic goes down and visa versa. Any ideas or a better way to do this?

wdbrewster Fri, 12/09/2005 - 12:34
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Sorry guys the problem did not go away. Please find attach the config. It works fine if I am just using NAT, put when I start building access-lists and firewall it just refuse to browse some sites and would not download files, but the VPN works fine between sites, I can use Remote Desktop Connection to other servers, I can use SDM and I can SSH.

Whats wrong guys?

wdbrewster Thu, 12/01/2005 - 06:48
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The ISP was doing some checks on their side so I am testing. I also reconfigured the router to only NAT at this time. If all goes well I will rebuild the firewall and VPN tunnels.

s.vyas Thu, 12/01/2005 - 07:20
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do this quick check for me pls...

telnet to the website(in question) on port 80 sourcing from the interface.


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