MLAG VS. Stacking: What Is Your Option?

2022-09-15 10:00:00
MLAG vs. stacking is something that has been thrown around many times – both of them are valid options to bond separate switches and manage them as a single logic switch, MLAG and stacking significantly improve network efficiency while simplify system management. So what makes the differences? When should we choose MLAG instead of switch stacking? We try to clear out some confusions by comparing MLAG vs. stacking features, pros and cons, then analyzing how to make a proper decision over MLAG vs. stacking.

MLAG vs. Stacking

Let’s start with the basics of MLAG and Stacking. Short for Multi-Chassis Link Aggregation, MLAG is the ability of two or more switches to act like a single switch when forming link bundles. This allows a host to uplink to two switches for physical diversity, while only have a single bundle interface to manage. Also, two switches could connect to two other switches using MLAG, with all links forwarding. Most MLAG implementation are totally proprietary, that means you are not able to an MLAG between different vendors.

Stacking, however, is usually something you may expect at the edge rather than the core of the network. It allows you to manage multiple switches as a single entity, which can be achieved by linking switch backplane or connecting uplink ports at the front. Likewise, stacking is supposed to happen between Ethernet switches in the same product line of the vendor.

Pros and Cons

Here we take a review of some of the pros and cons of MLAG and stacking, helping you to understand the benefits and limitations of each technology.

Pros of MLAG

· Traffic is more evenly distributed to each of the switches through the use of LAG hashing. And each switch is independently able for forward / route traffic without · passing to a switch
· Can simply bundle more links into the LAGs to increase bandwidth for North & South as well as East & West
· Offers more stability over stacking since it has dual management and control planes
· More suitable for switches that are geographically separate. However, when stacking remotely separated switches, the exponential of error increasing with distance
· Can upgrade one switch at a time without affecting service. Besides, it could expands port capacity beyond the limitation that you could with stacking - simply adding another switch East or West by creating another MLAG to another switch.

Cons of MLAG

· More complex to configure
· Have to configure/maintain each switch individually when using MLAG

Pros of Stacking

· Much simpler and easier to configure and manage
· Possibly easier to add more ports by adding an additional switch to the stack

Cons of Stacking

· Limited to number of switches that can be added to the stack or bond. Not able to add more bandwidth to stacking (but you can for bonding)
· Single control and management plane
· More inter-switch communication, as opposed to the ISC for MLAG

MLAG vs. Stacking: Which to Choose?

MLAG is useful to present diverse physical paths to hosts, and it also allows you to do software upgrade of the core. It can be an efficient tool to eliminate blocked Layer 2 links due to spanning-tree. MLAG can be used at various places in the network to eliminate bottlenecks and provide resiliency – at the leaf layer it offers active/active redundant connections from the server to the switches. While at the spine layer, it greatly enhances the Layer 2 scalability without increasing the cost. So if you need redundant Layer 2 connections and access to large portions of bandwidth, or your application servers require multi-path fabric architectures, MLAG would be a better design.

Stacking is a great fit for limited space deployment where flexibility trumps availability. As a pay-as-you-grow model, switch stacking is attractive for users that need flexibility in their physical network. However, the connecting distance is limited by the length of stacking cable – often within wiring closet. So if you have a small site that configuration simplicity is a matter, and bandwidth distribution to switches less of a concern, or your switches are in close proximity of each other, stacking could be your choice.

Lanbras offers a large portfolio of network switches with various port design and feature sets, including 10GbE switch, 25GbE switch, 40GbE switch and 100GbE switch. Some of them also have the function of MLAG and stacking.
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