HTTPS Traffic Slow over 877 router

jamesitsolutions · ‎02-13-2013

Hi Guys,

I am really ripping my hair out over this one, I have reconfigured the router from scratch using all sorts of methods and can not work out whats wrong, basically when the client is going to their bank the login screen takes upto a minute to load, and the same with hotmail. However using a cheap billion router these login screens are instant

Checking the CPU usage shows the CPU is hovering around 5-20% at the worst of times
There is about 10 machines behind this router and they do not do that much intensive work over the link besides Outlook Anywhere (HTTPS)
I have put a ACL on the LAN connection to only allow 1 machine in and still no luck
I have also updated the IOS to c870-advipservicesk9-mz.124-24.T4.bin
All other traffic runs fine over the link and there are no complaints on standard HTTP traffic

What can I look at to diagnose this issue, and what can I provide to help others work out whats wrong?

Andrew

johnlloyd_13 · ‎02-14-2013

Hi,

Kindly post show run. Do you have the 'ip tcp adjust-mss' configured?

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jamesitsolutions · ‎02-14-2013

Hi,

I had ignored the idea of MTU/MSS being a issue but thought I would give it a shot, orginally the MTU was 1492 on the ADSL Dialer, I lowered this to 1450 and set the MSS for VLAN1 to 1400 and the issue was resolved.

Not sure why this is so different, could different ISPs use different encapulations or something that would require the MTU to be different? :S

johnlloyd_13 · ‎02-14-2013

Hi Andrew,

I'm glad you've resolved the issue and my post somehow point you towards a resolution.

Setting or adjusting the IP MTU and MSS on your 877 ADSL router doesn't ensure packets won't be fragmented or dropped in transit. Each hop/router your packet traverses might be configured with different MTU size (ISP level).

If you've encountered a web connectivity issue (or other TCP-based applications), you can use commands such as ping -f -l or mturoute, that could help determine the MTU size of each hop between your network and destination.

Please help rate useful posts and marked if resolved. Thanks!

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