Slow network connection

[abdelnour.moussaoui]

Hello,

Based on the diagram attached that i have designed, i am experiencing very slow connection to the internet. i don't know why, i might be that something is wrong on this topology. could someone suggest what would be. 

by the way the internet connection is very fast once i plugged a computer directly to the DSL modem.

Any help is greatly appreciated.

[Mark Malone]

Hi

so I would work back then from the modem as you know its not the issue

start with the router check from there is it slow to the internet , if not move back to the switch,

Check each interface in path to the internet that traffic flows through , see if its overloaded or experiencing errors on any of the interfaces that may be effecting the throughput of the traffic

look for crcs , input errors etc , check the TX/RX of interfaces too

[Joseph W. Doherty]

DSL often uses PPPoE, which takes 8 bytes from MTU, which can cause fragmentation and/or transient interruptions to traffic while PMTUD "does it thing".

If this is the case, and you're not already using a smaller IP MTU and IP TCP adjust-mss, setting those make result in a performance improvement.