Enabling Jumbo Frames

[fma]

Enabled jumbo frames at Device, Setup, Session.  Question is, do I still have to go to each interface and specify the MTU size per interface or is the default value what I set at the device level?    Basically, if I don't touch the interfaces what MTU will each interface use by default (assuming I enabled jumbo's)?

Thanks!!!

[kadak]

Hello fma,

If you enable Jumbo Frames on the Device tab, it will be a global setting as you mentioned.  Any interface that has NOT CHANGED its default MTU size will inherit the jumbo frame size set in the global settings.  If you want a different interface setting then you can change it in the interface’s Advanced Tab.

Best to set the interfaces that you don’t want to have the jumbo frame size first and then set the global value after these have been configured.  This way, they don’t inherit the jumbo frame size unexpectedly.

In my lab, I checked the setting for Jumbo frames under Device tab, committed the changes and rebooted the firewall. All the connected interfaces inherited the global setting for MTU.

admin@55-PA-5060(active)> show system state filter-pretty sw.dev.interface.config

sw.dev.interface.config: {

ethernet1/3: {

    hwaddr: 00:1b:17:00:01:12,

    mtu: 9192,

  },

  ethernet1/5: {

    hwaddr: 00:1b:17:00:01:14,

    mtu: 9192,

  },

  ethernet1/6: {

    hwaddr: 00:1b:17:00:01:15,

    mtu: 9192,

  },

}

Hope the above recommendation helps you!

Thanks and regards,

Kunal Adak

[fma]

Hi Kunal,

Appreciate the fast response, and what I'm seeing is this -

(active)> show system setting jumbo-frame

Device Jumbo-Frame mode:                           on

Maximum of frame size excluding Ethernet header:   9192

Current device mtu size:                           9192

Indicating jumbo frames are enabled (and rebooted), but if I look at the interfaces I see:

(active)> show system state filter-pretty sw.dev.interface.config

sw.dev.interface.config: {

  ethernet1/21: {

    hwaddr: 00:1c:17:00:02:24,

    mtu: 1500,

  },

  ethernet1/22: {

    hwaddr: 00:1c:17:00:02:25,

    mtu: 1500,

  },

  ethernet1/23: {

    hwaddr: 00:1b:17:00:02:26,

    mtu: 1500,

  },

  ethernet1/24: {

    hwaddr: 00:1c:17:00:02:27,

    mtu: 1500,

  },

}

The 4 interfaces above form 2 aggregate interfaces and I'm using sub-ints within them.  Guessing I need to set each interface to 9192 to be certain.

Sub-Int config

ae3.12 {

                              ipv6 {

                                neighbor-discovery {

                                  router-advertisement {

                                    enable no;

                                    min-interval 200;

                                    max-interval 600;

                                    hop-limit 64;

                                    reachable-time unspecified;

                                    retransmission-timer unspecified;

                                    lifetime 1800;

                                    managed-flag no;

                                    other-flag no;

                                    enable-consistency-check no;

                                    link-mtu unspecified;

                                  }

                                  enable-dad no;

                                  reachable-time 30;

                                  ns-interval 1;

                                  dad-attempts 1;

                                }

                                enabled no;

                                interface-id EUI-64;

                              }

                              ip {

                                10.96.12.1/24;

                              }

                              adjust-tcp-mss no;

                              interface-management-profile ICMP;

                              tag 12;

Appreciate the help!

P

[kadak · Accepted solution]

Hello fma,

That's correct. For aggregate interface you would need to explicitly change it through the web-interface by inside the aggregate group.

In my lab, I tested it with ae1 having two interfaces 1/7 and 1/8.

admin@PA-3050> show system state filter-pretty sw.dev.interface.config   (Notice how 1/7 and 1/8 are still at 1500. )

sw.dev.interface.config: {

  ethernet1/1: {

    hwaddr: 00:1b:17:89:94:10,

    mtu: 9192,

  },

  ethernet1/15: {

    hwaddr: 00:1b:17:89:94:1e,

    mtu: 9192,

  },

  ethernet1/2: {

    hwaddr: 00:1b:17:89:94:11,

    mtu: 9192,

  },

  ethernet1/3: {

    hwaddr: 00:1b:17:89:94:12,

    mtu: 9192,

  },

  ethernet1/4: {

    hwaddr: 00:1b:17:89:94:13,

    mtu: 9192,

  },

  ethernet1/7: {

    hwaddr: 00:1b:17:89:94:16,

    mtu: 1500,

  },

  ethernet1/8: {

    hwaddr: 00:1b:17:89:94:17,

    mtu: 1500,

  },

}

MTU settings can be changed by  under ae1 > Advanced > Other info > MTU

Hope that answers your question!

Thanks and regards,

Kunal Adak

[fma]

Perfect, thanks Kunal!