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Aruba 8325 VSX not routing jumbo frames

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  • 1.  Aruba 8325 VSX not routing jumbo frames

    Posted Feb 14, 2020 12:38 AM

    We have just migrated our core L3 interfaces and routing from Juniper switches to a Aruba 8325 VSX.

     

    Since doing this we have found that Jumbo frames are no longing routing between VLANs. Such as a client on VLAN 2 trying to access a server on VLAN 3 with a packet larger than 1500.

     

    We have enabled the command (MTU 9198) on the physical interfaces that uplink to the rest of the network already.

     

    We have logged a call with support but they appear to be just guessing what is required and don't really know. Basically just saying try this or that.

     

    We believe we need to enable the command (ip mtu 9198) but do we need to do this under the physical interface or the VLAN interface?

     

    Below is some snipits of the related sections of our config.

     

    interface lag 22 multi-chassis
    no shutdown
    description Uplink to Juniper_Core
    no routing
    vlan trunk native 1
    vlan trunk allowed all
    lacp mode active

     

    interface 1/1/55
    no shutdown
    mtu 9198
    description Uplink to Juniper_Core
    lag 22

     

    interface vlan2
    vsx-sync active-gateways
    vrf attach vr-default
    ip address 10.46.2.2/23
    active-gateway ip mac 00:00:00:00:46:02
    active-gateway ip 10.46.2.1
    interface vlan3
    vsx-sync active-gateways
    vrf attach vr-default
    ip address 10.46.4.2/23
    active-gateway ip mac 00:00:00:00:46:04
    active-gateway ip 10.46.4.1

     

     

     

    Thanks,

    Nathan



  • 2.  RE: Aruba 8325 VSX not routing jumbo frames

    EMPLOYEE
    Posted Feb 14, 2020 03:40 AM

    Hello Nathan,

    Absolutely, you need larger ip mtu on the SVI (L3 vlan interface).

    MTU and IP MTU are covered in the VSX Best Practices guide:

    https://support.hpe.com/hpsc/doc/public/display?docId=a00094242en_us

     

    You may check configuration examples in appendix as well as explanation of MTU values in the step-by-step sections.