Reasons for MLAG on Summits


Userlevel 4
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

12 replies

Userlevel 4
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
André Herkenrath wrote:

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

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.
Userlevel 4
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.
Userlevel 4
Steven Lin wrote:

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.

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.
Userlevel 4
Steven Lin wrote:

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.

MLAG could support more complex scenario, and sometimes switches not Compatibility for stacking in your scenario.

Userlevel 4
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.
Userlevel 4
Tripathy, Priya Ranjan wrote:

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.

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
Userlevel 7
You can even use two SummitStacks to create an MLAG pair. Stacking and MLAG are complementary features.
Userlevel 4
Erik Auerswald wrote:

You can even use two SummitStacks to create an MLAG pair. Stacking and MLAG are complementary features.

Hello, Eric!

But why if I can connect two stacks via Etherchannel. This is much easily...
Userlevel 7
Erik Auerswald wrote:

You can even use two SummitStacks to create an MLAG pair. Stacking and MLAG are complementary features.

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
Userlevel 4
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=...
Userlevel 5
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

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