Update 2.3.4_1-> 2.4.0 -> broken ospf over gre[SOLVED]



  • Hello

    After update 2.3.4_1-> 2.4.0  ospf over gre looks broken

    #site1 ( 2.3.4_1 )
    logs
    Nov 4 09:47:58 ospfd 45632 Packet[DD]: Neighbor 10.10.10.18 MTU 1400 is larger than [gre1:10.10.10.25]'s MTU 1376
    Nov 4 09:47:53 ospfd 45632 Packet[DD]: Neighbor 10.10.10.18 MTU 1400 is larger than [gre1:10.10.10.25]'s MTU 1376
    Nov 4 09:47:48 ospfd 45632 Packet[DD]: Neighbor 10.10.10.18 MTU 1400 is larger than [gre1:10.10.10.25]'s MTU 1376
    Nov 4 09:47:43 ospfd 45632 Packet[DD]: Neighbor 10.10.10.18 MTU 1400 is larger than [gre1:10.10.10.25]'s MTU 1376

    #site2 ( updated to 2.4.0 ) <- ospf broken
    #route
    10.10.10.25 link#12 UH 2322 1376 gre2

    #logs
    Nov 4 16:50:04 ospfd 52879 *** sendmsg in ospf_write failed to 224.0.0.5, id 0, off 0, len 64, interface gre2, mtu 1400: Permission denied

    It looks like site2 after upgrade it not sending correct MTU info to it peer on site1
    GRE header ignored may be .

    Please advice .



  • Can you try adding a floating rule for this?



  • workaround was :

    MTU settings for GRE interfaces
    new 2.4 version MTU 1376
    old 2.3.4 version MTU 1400

    in this case
    old<–> old <--working
    old<--> new <--working
    new<--> new <--working