poor response from WAN Sites to 1 application

[Ahmed Shaheen]

Greetings everyone,

i am facing one of the most undesired problems in Networks.. unconditional slowness.

however when accessed from other sites, it is reported as perfect response.

scenario,

an Application that is being accessed through the WAN is reported to be slow from a specific site/branch.

Netflow does not show any utilization on the WAN. the WAN speed is over 30Mbps

policy-map does not show any violations on the ACL.

Core switches and access switches does not show any CPU utilization.

User's Workstations does not show any memory/CPU utilization.

after reading and reading and searching for a way to troubleshoot this with, i can't find any lead on the same.

what do you suggest i address the above?

[Joseph W. Doherty]

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Posting

Does this one site have a higher latency than the other sites?

[Ahmed Shaheen]

when we say latency, you mean the response of PING, which is no.. there is no latency as such when we ping the server from the site.. it is always less than 5 msec.

but when we say application response.. it is a yes.. the response is very poor comparing to other sites.

[Joseph W. Doherty]

So, you're saying all the sites achieve about the same latency?

What's the WAN technology?

[Ahmed Shaheen]

No, this one specific site faces the poor response, I am using gre tunnel.

and only this application is slow not others

[Joseph W. Doherty]

Yes, I understand all that, but what I'm asking is, is the one slow site have about the same latency as the other sites.  Some applications can be very "chatty", and just a few extra milliseconds of latency will slow them much (compared to other applications).

Ah, you mention using a GRE tunnel.  All sites use GRE tunnels too?

[Ahmed Shaheen]

yes it has the same latency, or maybe even less as it has higher speed than others, and yes all the others are using GRE.

i guess the problem is within the lan, but i can't get a lead on troubleshooting switching.. even though i checked all switches on the edge.

the only thing is i see undersized packets when i sh the interfaces counters errors.

[Jon Marshall]

You need to narrow down the issue.

So you know only one site has this problem so start there obviously which is what you have done.

Are there other applications accessed over the WAN being used and if so what is that performance like compared to other sites ?

If there are other applications and they are fine then it suggests an application specific issue in which case you need to look at the packets using a packet capture tool and see what is happening.

If there are no other apps then it could be a LAN issue. Are there any firewalls or acls at each site and are you potentially blocking something needed for the application.

For example in both of the above a simple DNS issue within the application could cause very poor response times and that could be one of many things.

If you can eliminate a lot of potential issues then you can concentrate on what is the most likely cause.

Jon