Website loading blank page

kartik.shah1 · ‎10-21-2016

Hi,

I have cisco 1941 wan router. I have Ebgp routing with ISP. I have my own AS number.

Problem we are facing is 1 specific website' page is loading blank.

I tried to ping that website, it worked perfectly.

I tried to trace route that website, it worked.

Scenario i tested:

I connected laptop to LAN port of cisco router 1941,Ping & trace route worked properly, but web page loads blank page.

But if i bypass my cisco router 1941, i am able to load website page perfectly.

I have attached scenario.

Thank you,

Regards,

Georg Pauwen · ‎10-22-2016

Hello,

MTU settings on your interface might cause that problem. Try ip mtu 1492, or tcp ip adjust-mss 1452 on your external interface.

kartik.shah1 · ‎10-22-2016

Hi gpauwen,

On router interface, MTU is 1500. So if i change MTU at interface to 1492, will it not create same issue for other websites??

Thank you,

Regards,

Georg Pauwen · ‎10-22-2016

Kartik,

shouldn't be a problem. What website is it anyway you are having trouble with ?

kartik.shah1 · ‎10-22-2016

Gpauwen,

This website was working properly 3-4 weeks back. Suddenly we faced this issue.

Name of website is "www.ndimensionz.com".

thank you.

regards,

Georg Pauwen · ‎10-22-2016

Check the output of the ping results. Anything above 1472 is fragemented. Try and set your MTU to 1472 and check if you can access the website.

C:\windows\system32>ping www.ndimensionz.com -f -l 1473

Pinging ndimensionz.com [169.53.140.68] with 1473 bytes of data:
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.

Ping statistics for 169.53.140.68:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),

C:\windows\system32>ping www.ndimensionz.com -f -l 1472

Pinging ndimensionz.com [169.53.140.68] with 1472 bytes of data:
Reply from 169.53.140.68: bytes=1472 time=223ms TTL=53
Reply from 169.53.140.68: bytes=1472 time=179ms TTL=53
Reply from 169.53.140.68: bytes=1472 time=218ms TTL=53
Reply from 169.53.140.68: bytes=1472 time=209ms TTL=53

Ping statistics for 169.53.140.68:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 179ms, Maximum = 223ms, Average = 207ms

kartik.shah1 · ‎10-22-2016

Gpauwen,

should i configure mtu size 1472 on router interface?

if yes, where should i confiigure it on lan or wan interface? & what config command i have to run?

And it will not affect other working website?

regards,

Georg Pauwen · ‎10-22-2016

Hello,

apply it to the WAN interface with the command 'ip mtu 1472'. Other websites are not affected.

kartik.shah1 · ‎10-22-2016

Hi gpauwen,

thank you,

i will try this.

is there any thing more to do? only this config command?

and if you have any manual/config guide for this do share.

regards,

Georg Pauwen · ‎10-22-2016

If the mtu command on the WAN interface doesn't work, try 'ip tcp adjust-mss 1452' on the LAN (Fast)Ethernet interface.

I don't know of a comprehensive guide, but the problem with access to certain websites and MTU settings has been around for quite a while, so it is usually suggested to change MTU size as a possible solution.