Unable to open some of the websites

[Mohammed Asif C Y]

Hi Team,

I have Cisco 3825 router and configured a Gig0/0 for the internet link. Recently we have observed that some of the sites like facebook/sbi/supportforums.cisco.com not opening. Whereas i am able to open all other sites like cisco.com/twitter.com

Can someone please help me on this

interface GigabitEthernet0/1
 mtu 1500
 ip address x.x.x.x. 255.255.255.252
 ip virtual-reassembly
 no ip route-cache cef
 no ip route-cache
 ip tcp adjust-mss 1450
 load-interval 30
 duplex auto
 speed auto
 media-type rj45
 hold-queue 524 in
 hold-queue 524 out

|

router bgp xxxx
 bgp log-neighbor-changes
 neighbor x.x.x.x remote-as x.x.x.x
 neighbor  update-source GigabitEthernet0/1
  maximum-paths 2

Regards

MAC

[Nish Vamadevan]

It may be an MTU issue... Have you tried changing the MTU to reflect the one set by your ISP?

[Mohammed Asif C Y]

Hi Nish,

Yes i have tried changing the MTU and also the tcp MSS value but no luck

Will changing the value in Weight will do any difference?

neighbor x.x.x.x weight 550

Regards

MAC

[Nish Vamadevan]

How many BGP peers do you have? 1?

Weight is locally significant and also check the hold-queue, as "Cisco recommends that the queue size not exceed ten packets on asynchronous interfaces"

I would do a packet capture and see whats going on...

[Mohammed Asif C Y]

Hi Nish,

We have only one BGP Peers, some few days back we were having two but i have removed the unwanted configuration.

As of now MTU size is 1500, i tried changing it but no luck

Regards

Asif C Y

[Nish Vamadevan]

Can you please explain why the following is there...? Have a packet capture and see whats going on...

router bgp xxxx
 bgp log-neighbor-changes
 neighbor x.x.x.x remote-as x.x.x.x
 neighbor  update-source GigabitEthernet0/1
  maximum-paths 2

[Mohammed Asif C Y]

Hi Nish,

The config you are referring has been removed for now and tested. But no proper results, i am trying to run debug commands and take results

Regards

Asif C Y

[Nish Vamadevan]

Can you try TCP MSS to 1452 and double check the MTU, I really think one of them is causing it...

[Richard Burts]

I do not know that it would cause this problem but I question why this is configured on the interface

 no ip route-cache cef

Using CEF usually improves performance and when you turn it off you should result in all packets being process switched which does impact performance.

I also wonder why this is on the interface

 ip virtual-reassembly

and it makes me think that fragmentation and reassembly may be the issue. As a test I suggest that you use the ip tcp adjust-mss to 1300 and see if the behavior changes.

HTH

Rick