21st April 2016 by Martin Flammia

Filed under Extreme Networks Configuration, Extreme Networks EXOS

Last modified 25th August 2017

Here are the some shortcuts to GTAC articles:




First off decide on ports to be used for the ISC, and if more than one configure them as a lag:

Then create a /30 (recommended) Vlan / Subnet for the ISC link, and put the proposed ISC ports into the Vlan, tagged:

Configure IP address for local ISC link:

Configure IP address too remote ISC link (peer)

Warning: In this case was displayed having not configured sharing as provided as first step in this example.

The example below is what will be shown should both ends of the MLAG be configured but yet to configure a lag to the edge. The point here is that ‘MLAG ports’ show’s 0 (zero), but the ‘Peer MAC’ is populated.

Now that the ISC link is working its time to configure the MLAG ports, of which in this example port 1 on each of the core’s will form the lag to the edge. Here you defining the port you want to configure, what ISC link (peer) to use and a common id for the lag:

The ‘show mlag peer’ now looks like the following:

For this post VRRP (active / active) is to be configured inline with MLAG. So the for the purpose of testing the following Vlan has been created and added tagged to the mlag port 1:

VRRP is then configured using as the VIP address:

In order to have VRRP work as active / active an ACL is written to block the VRRP multicast between the two cores:

Then added to the ISC port:

If when both cores are configured for MLAG and VRRP and VRRP gets stuck in INIT mode as per below:

Then make sure you have the three lines configured properly on both cores, but primarily that port 1 is up in order to bring VLAN up (unless you configure a loopback that is):

VRRP will then change:





Configure Vlan and lag:

With a laptop plugged into the edge switch port 10, with an IP address in the 10.100.10.x you should then be able to ping the VRRP VIP address. You can then test resiliency by pulling links.

One thing to be mindful of is if when looking at Vlan (lab), and with everything connected it is showing blocking as per below:

This is probably due to only one side of the lag configured for LACP.

If the core is the side that does not have LACP enabled the process is as follows:






  1. Rui Marques

    Hello, I believe there’s a typo on the following lines of configuration :

    SWITCH 2

    create vlan MLAG-ISC
    configure vlan “MLAG-ISC” tag 255
    configure vlan “MLAG-ISC” add ports 49 tagged
    enable sharing 49 grouping 49,53 lacp algorithm address-based l3_l4
    configure vlan “MLAG-ISC” ipaddress
    create mlag peer MLAG-PEER-254
    configure mlag peer “MLAG-PEER-254” ipaddress
    create vlan “lab”
    configure vlan “lab” tag 100
    configure vlan “lab” add ports 1 tagged
    enable mlag port 1 peer “MLAG-PEER-253” id 100
    create vrrp vlan lab vrid 1
    configure vrrp vlan lab vrid 1 add
    enable vrrp vlan lab vrid 1

    * It sould be (and correct me if I’m wrong) :
    enable mlag port 1 peer “MLAG-PEER-254” id 100

    18th July 2018 - 3:22 pm – Reply

    • Hi Rui, thanks for pointing that out, your absolutely correct! It’s an old article too, but I’ll get that updated. Cheers, Martin

      18th July 2018 - 9:18 pm – Reply

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