Application Slow with Router ACL

[vamsi harish]

Hi,

We have been facing a strange issue in our network. When we implement an ACL on a router or a L3 switch at branch end the Citrix App launch or any other web services are getting slow. But when we access the same application without ACL, it's very fast. I did check the latency from network side with and with out ACL, but didn't find any delay. Kindly suggest what can cause this kind of issue.

Thanks,

[Yachay]

Please, could you add a simple diagram indicating which interface your ACL is applied on, hosts, direction and some lines of the ACL?

[Jon Marshall · Accepted solution]

You have probably blocked some ports that are needed such as DNS for name lookups etc. 

Easiest thing to do is to temporarily add a deny line and log it so you can see what is being blocked. 

Jon

[vamsi harish]

We did the same and allowed the required dependencies which were getting blocked earlier. Now the application started working normal. Thanks for your response.