RFC4638? Baby jumbo frames for PPPoE connections (MTU 1508)

  • Hi,

    Does 2.2-RELEASE support baby jumbo frames for PPPoE?  That would be great for FTTC connections in the UK.

    Many thanks!

    • Martin.

  • Rebel Alliance Developer Netgate

    I believe so, there was at least one, possible more, forum thread about it in the 2.2 development board.

  • Any idea how this might work on pfSense? Simply setting the WAN MTU to 1508 doesn't work for me.

    My GPON internet does RFC 4638. I could connect and ping 1472 bytes using Openwrt BB.

  • I set the following:
    WAN MTU to 1500
    interfaces>PPPs>pppoe0> MTU = 1500 and MRU =1500

    Result: everything looks ok from the outside except ping.

    [2.2-RELEASE][root@pfSense.playgroup]/root: ifconfig pppoe0
    pppoe0: flags=88d1 <up,pointopoint,running,noarp,simplex,multicast>metric 0 mtu 1500
            inet --> netmask 0xffffffff
            inet6 fe80::20c:29ff:feb2:e4ab%pppoe0 prefixlen 64 scopeid 0x7
            nd6 options=21 <performnud,auto_linklocal>[2.2-RELEASE][root@pfSense.playgroup]/root: ifconfig vmx0
    vmx0: flags=8843 <up,broadcast,running,simplex,multicast>metric 0 mtu 1500
            options=60079b <rxcsum,txcsum,vlan_mtu,vlan_hwtagging,vlan_hwcsum,tso4,tso6,lro,rxcsum_ipv6,txcsum_ipv6>ether 00:0c:29:b2:e4:ab
            inet6 fe80::20c:29ff:feb2:e4ab%vmx0 prefixlen 64 scopeid 0x1
            nd6 options=21 <performnud,auto_linklocal>media: Ethernet autoselect
            status: active
    [2.2-RELEASE][root@pfSense.playgroup]/root: route get
       route to: google-public-dns-a.google.com
    destination: default
           mask: default
            fib: 0
      interface: pppoe0
          flags: <up,gateway,done,static>
     recvpipe  sendpipe  ssthresh  rtt,msec    mtu        weight    expire
           0         0         0         0      1500         1         0
    [2.2-RELEASE][root@pfSense.playgroup]/root: ping -c 4 -s 1472
    PING ( 1472 data bytes
    --- ping statistics ---
    4 packets transmitted, 0 packets received, 100.0% packet loss
    [2.2-RELEASE][root@pfSense.playgroup]/root: ping -c 4 -s 1462
    PING ( 1462 data bytes
    1470 bytes from icmp_seq=0 ttl=50 time=119.920 ms
    1470 bytes from icmp_seq=1 ttl=50 time=116.631 ms
    1470 bytes from icmp_seq=2 ttl=50 time=116.487 ms
    1470 bytes from icmp_seq=3 ttl=50 time=116.757 ms
    --- ping statistics ---
    4 packets transmitted, 4 packets received, 0.0% packet loss
    round-trip min/avg/max/stddev = 116.487/117.449/119.920/1.430 ms</up,gateway,done,static></performnud,auto_linklocal></rxcsum,txcsum,vlan_mtu,vlan_hwtagging,vlan_hwcsum,tso4,tso6,lro,rxcsum_ipv6,txcsum_ipv6></up,broadcast,running,simplex,multicast></performnud,auto_linklocal></up,pointopoint,running,noarp,simplex,multicast>

  • I suppose PPPoE in pfSense/FreeBSD is maximum of 1492

    Feb 6 10:36:14	ppp: mpd_wan.conf:31: Error in 'set link mtu 1500': max MTU on type "pppoe" links is 1492
    Feb 6 10:36:14	ppp: mpd_wan.conf:32: Error in 'set link mru 1500': max MRU on type "pppoe" links is 1492
    Feb 6 10:36:14	ppp: [wan_link0] Link: OPEN event
    Feb 6 10:36:14	ppp: [wan_link0] LCP: Open event

    More info
    Baby jumbo frames (MTU 1508) for PPPoe connections?

  • Anyone got it working already? Just like in the UK many Fiber optic providers in the Netherlands use PPPoE and support RFC4638. So it would be great if we can get it working.

  • I'm prepared to offer a bounty to anybody who makes this happen. Bounty thread started for those who would like to contribute
    RFC 4638 (PPPoE 1508 MTU) - let's pitch in