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Fragmented Packets?

Discussion in 'Cisco Small Business Routers and VPN Solutions' started by bent42, Aug 29, 2006.

  1. bent42

    bent42 LI Guru Member

    I'm connecting to the WRV54G at the office with QuickVPN.

    The Linky is behind an ADSL modem, both with static IPs from my DSL provider.

    It used to work fine, but it seems to be fragmenting packets through the VPN now. No effects on normal traffic, either internet or local. The packets are so bad that my software firewall at the client end detects it as a DOS attack :confused:

    I've flashed the router to the 2.39.2 firmware, and am using the latest QuickVPN Client, no love.

    As far as I can tell, it is a problem with the router, not the clients. I've tried several client computers at several locations with various states of firewall, and the problem stays. Anybody else see this problem? Any sugestions on what I should try?
  2. Toxic

    Toxic Administrator Staff Member

    try lowering your MTU size on the WRV54G. what are you running it at the moment. for Normal ADSL use it should be no more than 1492, but using VPN this would need to be lower again.
  3. bent42

    bent42 LI Guru Member


    Is there a formula for determining what the MTU should be set at, or do I just set it low (1400) and go up from there untill it stops working?

    That is definitely the problem, I set it to 1400, and viola, the VPN works like a charm.
  4. OpticalMan

    OpticalMan LI Guru Member

    I think it's 1420 for DSL+VPN combo. 1428 for Cable+VPN.

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