ExtremeSwitching (EXOS)

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  • 1.  Jumbo Frame & IP MTU

    Posted 11-19-2015 01:21
    Hi,

    If I'm using "configure ip-mtu vlan" for specifying MTU size for a specific VLAN, should I use "enable jumbo-frame ports" for each port associated to that VLAN?

    What is the relation with "configure jumbo-frame-size" if there are more than one tagged VLAN with different MTU on "configure ip-mtu vlan" with same associated ports?

    Best regards,


  • 2.  RE: Jumbo Frame & IP MTU

    Posted 11-19-2015 04:55
    As per our implementation,"config ip-mtu size vlan" doesn't impact ipv4 jumbo frame data path traffic provided whether jumbo frame is enabled on ingress and egress L3 vlan ports using cmd "enable jumbo-frame ports".So, for fast path routing of ipv4 jumbo frame we need to enable jumbo-frame ports.

    I believe there is no relation of "configure jumbo-frame size" with different L3 MTU for more than one tagged VLAN as for as ipv4 data path traffic is concerned .

    L3 MTU size impact only l3 slow path traffic and some routing protocols.


  • 3.  RE: Jumbo Frame & IP MTU

    Posted 11-19-2015 06:52
    enable jumbo-frame ports is for L2 switching of packets.
    The IP-MTU setting on vlans is for L3 routing to route jumbo frames.

    You cannot increase the ip-mtu without also enabling jumbo frames on the involved ports.


  • 4.  RE: Jumbo Frame & IP MTU

    Posted 11-19-2015 10:06
    HI Oscar,

    Can you give me some example of mixed tagged and untagged VLAN configuration of a port with different MTU for each VLAN (some with normal 1500 MTU)?

    Best regards,


  • 5.  RE: Jumbo Frame & IP MTU

    Posted 11-19-2015 10:41
    Just enable jumbo-frames on the ports, keep the default jumbo-frame size.
    Then for each vlan you need to route bigger packets set the ip-mtu for that vlan to the value needed. Add the vlans to the ports.