PPOE and MTU setting(s)

  • I am running Pfsense 2.2 RC (Jan. 5 build). After doing some reading, if I understand correctly, I should set the MTU on my Wan interface to 1492 instead of leaving it blank which defaults to 1500. Is this correct? Do I also need to change the lan and vpn client?


  • Whare do you live and what type of net access do you have, cable or adsl or something else?

    My understanding of MTU's are based on the UK experience, but UK ADSL will be 1492 and UK cable will be 1500, cant say how that compares elsewhere in the world.

    Might be useful. http://en.wikipedia.org/wiki/Maximum_transmission_unit#Table_of_MTUs_of_common_media

  • Netgate Administrator

    It's not normally necessary to set it. It should negotiated during the connection process.
    For example my WAN here at home is PPPoE, I have not set any MTU or MSS value at the interface setup. Also in the UK.
    In the PPP log I can see:

    Jan 6 18:09:01 	ppp: [wan_link0] MRU 1492

    Also if I interegate the interface at the command line I can see:

    [2.1.5-RELEASE][root@pfsense.fire.box]/root(2): ifconfig pppoe0
    pppoe0: flags=88d1 <up,pointopoint,running,noarp,simplex,multicast>metric 0 mtu 1492
    	inet6 fe80::290:7fff:fe3c:9609%pppoe0 prefixlen 64 scopeid 0xd 
    	inet 87.113.*.* --> 195.166.*.* netmask 0xffffffff 
    	nd6 options=3 <performnud,accept_rtadv></performnud,accept_rtadv></up,pointopoint,running,noarp,simplex,multicast> 


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