Hello Experts,

I have a VPLS link which passes via Cisco switches 2960s, link works, is able to pass ping's no problem, the problem happens when trying to use network resource, like http starts but then goes to blank screen.

The MTU on cisco switch is set to 1998, system MTU and Jumbo frames enabled 9000. Other switches on network like Procurve are ok. Bypassing the cisco switch and connecting directly, makes everything work perfectly.

Any idea on what could be the issue ? As i have read everything regarding VPLS and Cisco and nothing seem to apply here.

Thanks for your time.

Since you describe an issue which only shows up with significant traffic I would double check that the links are negotiating correctly. When Cisco switches don't manage to negotiate the speed/duplex they often drop to speed sensing in which case they might get the speed right but select half-duplex. That can produce similar symptoms when the other end is on full duplex.

If that checks out then at least it is ruled out as an issue.

Duplex speeds are fine on interface, and i don't have load at all, for test I just one pc connecting.
I am able to ping on other side but cannot browse webpages.
The only config on switch is VTP transparent, and have few vlan. But i am using native vlan.

Sounds like a MTU issue. What is the outgoing MTU on your Mikrotik. Also are you plugged into a GigE port or a 10/100?

does ping With large frame size pass? what is Maximum frame that pass? ( on layer2)

sorry guys, I had a Mikrotik x86, as bridge and should not have been an issue but this one was giving problem for some reason. removed and its all good.