PPOE Problem, Accept Large UDP Packets? (2.0RC3)

  • Hi,

    First of all, what a great bit of software PFSense is. I've moved over from Smoothwall and love the extra functionality and ease of use.

    We've got a really odd problem with our VOIP, I'm getting packet fragmentation purely on inbound calls from my VOIP provider, so no call INVITE requests are making it to the PBX.

    The setup giving the problem is a Draytek 2820, set in PPOE pass-through mode, MTU set to 1472 (the ISP says anything between 1400 and 1500 is fine). This router worked fine in this exact configuration with smoothwall (different firewall box though).

    I've tried enabling and disabling IP Do-Not-Fragment compatibility, also Disable Firewall Scrub.

    We don't seem to have any problems with any other traffic, and this issue seems to be restricted to the VOIP provider we use (VOIP-Unlimited) and their implementation of Fax over IP. The provider is saying that the problem is either the ISP or the Firewall/Router.

    When the Router is working in normal NAT mode, there is a setting of "Accept large incoming fragmented UDP or ICMP packets", is there a setting somewhere in PFsense somewhere to do the equivalent of this.

    If it's any help I can get the SIP traces from the website, or if any other data is needed then just shout.

    Many thanks,


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