6rd and MTU settings



  • My cable ISP is offering ipv6 through 6rd and I manged to make it work on my Alix box with 2.1.5. Everything seems to work correctly and all the LAN clients are able to connect using their ipv6 addresses.
    The only question I have is related to the MTU settings. According to my ISP the MTU for the 6rd tunnel should be set to 1480, but in pfSense I only see the MTU setting for the WAN interface, but nothing specific for 6rd.



  • @MaxPF:

    The only question I have is related to the MTU settings. According to my ISP the MTU for the 6rd tunnel should be set to 1480,

    But if you have no problems, then leave it as is…
    Do not mess around with MTU unless obviously you know what you are doing !



  • Agreed! Mine was mostly a curiosity especially after seeing screenshots of other products where the MTU value was part of the 6rd configuration.



  • I renew this old thread because, at today (2.3), I think would be useful  a way to set the right MTU in a 6rd ipv6 environment.
    Currently mtu is hardcoded to 1280…. but in case of ipv4 mtu 1500 on the wan, the right (and optimal) value should be 1480... (wan mtu minus 20).
    What do you think about?


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