ExtremeSwitching (EXOS)

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Reasons for MLAG on Summits

  • 1.  Reasons for MLAG on Summits

    Posted 12-06-2016 06:30
    Hello, everybody!

    I am an engineer at partner company and we are going to make a business event for our customers. My presentation is about MLAG on BD8806 with VRRP.

    I suppose that I will be asked a question about why there is MLAG on Summit Switches, which could be stacked easily?

    Could you please give me some ideas?

    Many thanks in advance,

    Ilya



  • 2.  RE: Reasons for MLAG on Summits

    Posted 12-06-2016 06:33
    It's about downtime. When you upgrade a stack, the whole stack must be rebooted. When you upgrade a pair of MLAG-Switches you can upgrade and reboot one by one. With the right design you can achieve a always up core.

    Andre


  • 3.  RE: Reasons for MLAG on Summits

    Posted 12-06-2016 06:33
    Besides what André already said, When you stack, the control of the stack is made only by the master control plane. The other switches are serving only the ports. On a MLAG configuration, both control planes are active and processing, so load is shared, and processing capability is added.



  • 4.  RE: Reasons for MLAG on Summits

    Posted 12-06-2016 06:48
    The MLAG feature allows you to combine ports on two switches to form a single logical connection to another network device. The other network device can be either a server or a switch that is separately configured with a regular LAG
    to form the port aggregation.



  • 5.  RE: Reasons for MLAG on Summits

    Posted 12-06-2016 06:48
    The MLAG feature allows you to combine ports on two switches to form a single logical connection to another network device.

    Why couldn't I do the same with etherchannel? Make 2-summits stack and give a link from both to a required host. At host's side configure teaming or NIC bonding.

    I don't understand the diffrence, please, explain.


  • 6.  RE: Reasons for MLAG on Summits

    Posted 12-06-2016 06:48
    MLAG could support more complex scenario, and sometimes switches not Compatibility for stacking in your scenario.



  • 7.  RE: Reasons for MLAG on Summits

    Posted 12-06-2016 07:17
    Apart from the above features there are also single-tier MLAG which provides the redundancy at the access level.
    Second is the two-tier MLAG design provides the redundancy at the distribution level or the core-level.



  • 8.  RE: Reasons for MLAG on Summits

    Posted 12-06-2016 07:17
    Hello, could you please explain it in details?

    "single-tier MLAG which provides the redundancy at the access level."

    and

    "Second is the two-tier MLAG design provides the redundancy at the distribution level or the core-level. "

    Many thanks in advance,

    Ilya


  • 9.  RE: Reasons for MLAG on Summits

    Posted 12-06-2016 07:32
    You can even use two SummitStacks to create an MLAG pair. Stacking and MLAG are complementary features.


  • 10.  RE: Reasons for MLAG on Summits

    Posted 12-06-2016 07:32
    Hello, Eric!

    But why if I can connect two stacks via Etherchannel. This is much easily...


  • 11.  RE: Reasons for MLAG on Summits

    Posted 12-06-2016 07:32
    Hi Ilya,

    for example, you can use 8 switches to form 4 MLAG pairs, or you can use two stacks of 4 switches each and create one MLAG pair.

    Stacking can be viewed as a method to create a chassis-like virtual switch using standalone switches.

    MLAG allows to connect one downstream device, e.g. a server, to two independent upstream devices using port sharing (aka LAG or port-channel).

    Why would you set up MLAG between two chassis switches, if you can more easily use two modules inside the chassis for redundant connections?

    Erik


  • 12.  RE: Reasons for MLAG on Summits

    Posted 12-06-2016 08:04
    Please find below this article link which explains the two tier MLAG design in details:

    https://gtacknowledge.extremenetworks.com/articles/How_To/Sample-configuration-for-two-tier-MLAG/?q=...



  • 13.  RE: Reasons for MLAG on Summits

    Posted 12-08-2016 09:17
    This very question was asked about a year ago and I believe there are some very insightful responses that came from the community. I hope the following thread can help answer your questions: https://community.extremenetworks.com/extreme/topics/mlag-vs-stack-what-am-i-missing