Slow internet download behind ASA 5520

[jthombs1016]

I have a strange Internet  connection issue.We have  dirty network for our 3rd party users running on a  6500 switch with ASA 5520.

We get decent upload speeds of over 80mbps but only  10mbps down.  I am unable to see any duplex problems on the main connections.

I  have attached a  diagram of the main  connections.  The ISP report no issues  on their router including no miss matches  or CRCs .

Has anyone see this sorty of issue before.  ? What steps can I take.

[Philip D'Ath]

Are your interface counters clean of increasing errors?

Perhaps try reducing the MSS on the ASA to see if it changes the issue or not (in case there is an MTU squeeze happening).  Change it back if it makes no difference.

[jthombs1016]

Hi Philip

Sorry for the delaying answering but the counters look clean  not sure how to change  MSS..

I will do some research.

[Philip D'Ath]

http://www.cisco.com/c/en/us/support/docs/security/asa-5500-x-series-next-generation-firewalls/113393-asa-troubleshoot-throughput-00.html

Try (as a test - and then remove when done):

sysopt connection tcpmss 1000