831 DSL (Can only access some web sites)

Answered Question
Dec 26th, 2007

Hi,

I just got and configured a Cisco 831 router. The IOS is 12.4. The router is connected to a DSL modem and goes to internet. The problem is, from PC in my LAN, only some web sites can be accessed, like google.com. Some web sites cannot be opened, like weather.com. I tried trace route, the routing goes to the 831 router (the only gateway). I telnet to 80 port of those web sites, and it works.


Here are the tests I did from PC1 in my LAN:

1. In IE, open google.com website, result: Webpage looks good.

2. In IE, open weather.com website, result: Webpage doesn't open.

3. In DOS prompt, do "telnet weather.com 80", get the black screen, means telnet session is established to weather.com's 80 port.

4. Same problem with other PC

5. If I swap the Cisco 831 with a consumer level router, everything works.


So I'm suspecting something wrong with the Cisco 831 above Layer 4. But it's just my guess, as I got absolutely no clue.

Can you please advise? I attached my running-config.

ANY suggestion will be greatly appreciated!!!



Correct Answer by Paolo Bevilacqua about 9 years 2 months ago

Hi,


please configure;


int dialer1

ip tcp adjust-mss 1452


You can also simplify your configuration with:


no ip name server .... (repeat for all the DNS)

no ip route 0.0.0.0 0.0.0.0 dialer1


int dialer 1

ppp ipcp dns request

ppp ipcp default route


Finally, you don't need "ip forward-protocol nd".


Hope this helps, please rate post if it does!


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Correct Answer
Paolo Bevilacqua Thu, 12/27/2007 - 03:29

Hi,


please configure;


int dialer1

ip tcp adjust-mss 1452


You can also simplify your configuration with:


no ip name server .... (repeat for all the DNS)

no ip route 0.0.0.0 0.0.0.0 dialer1


int dialer 1

ppp ipcp dns request

ppp ipcp default route


Finally, you don't need "ip forward-protocol nd".


Hope this helps, please rate post if it does!


panweicisco Thu, 12/27/2007 - 07:47

The commands fixed my problem!!! :D

I don't know how to express my appreciatation!

Thank you so so so much!

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