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mlwebster's avatar
mlwebster
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Jan 03, 2024

F5 appliances failing to establish OSPF with attached devices

Hi all, there is a little known 'feature' in the underlying Linux OS that has a hard limit of 20 network statements. If you go beyond 20, the additional networks will not be advertised in OSPF. I ...
application delivery
network
ospf
  • mlwebster's avatar
    mlwebster
    Icon for Cirrus rankCirrus
    Jan 04, 2024

    Hi,

    the networks are all in the same area

    pre super-netting (21 statements)

    networks 10.x.x.0/24 area n
    networks 10.x.x.0/24 area n
    networks 10.x.x.0/24 area n
    networks 10.x.x.0/24 area n
    networks 10.x.x.0/24 area n
    networks 10.x.x.0/24 area n
    networks 10.x.x.0/24 area n
    networks 10.x.x.0/24 area n
    networks 10.x.x.0/24 area n
    networks 10.x.x.0/24 area n
    networks 10.x.x.0/24 area n
    networks 10.x.x.0/24 area n
    networks 10.x.x.0/24 area n
    networks 10.x.x.0/24 area n
    networks 10.x.x.0/24 area n
    networks 10.x.x.0/24 area n
    networks 10.x.x.0/24 area n
    networks 10.x.x.0/24 area n
    networks 10.x.x.0/28 area n
    networks 10.x.x.0/22 area n
    networks 192.168.x.0/29 area n

    here, the 192.168 subnet wasn’t advertised

     

    post super-netting (12 statements)

    networks 10.x.x.0/24 area n
    networks 10.x.x.0/24 area n
    networks 10.x.x.0/24 area n
    networks 10.x.x.0/24 area n
    networks 10.x.x.0/24 area n
    networks 10.x.x.0/24 area n
    networks 10.x.x.0/24 area n
    networks 10.x.x.0/20 area n
    networks 10.x.x.0/21 area n
    networks 10.x.x.0/28 area n
    networks 10.x.x.0/22 area n
    networks 192.168.x.0/29 area n

    now working fine

    If I was unable to super-net I’d need to use – I tested this before implementing the super-netting

    net.ipv4.igmp_max_memberships=25 (>20)

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