Question

What is the difference between a LAG and a MLAG?

Answer 1

What Is MLAG Networking?

MC-LAG networking is a networking type achieved by MC-LAG technology. MLAG (MC-LAG), abbreviation for Multi-Chassis Link Aggregation Group, is a new multi-device link aggregation technology for data center Ethernet switches. MLAG configuration centralizes constituent ports on separate chassis, mainly serves as reliable load functionality to increase bandwidth and provide redundancy in emergent breakdown of one of the device. MC-LAG networking is introduced by Arista in 2012. LAG is defined in the IEEE 802.1AX-2008 standard, where MC-LAG is not involved. Instead, MLAG implementations are vendor-specific. Say MC-LAG Juniper and mLACP Cisco. However, the combined chassis is still compliant to the IEEE 802.1AX-2008 standard.

Differences

• Rooted in LAG but not ceased to advance, MC-LAG adds node-level redundancy to the normal link-level redundancy. As thus MLAG networking enables more virtual switches to simultaneously share the same LAG endpoint. In this way bandwidth is expanded and redundancy is enhanced once again.
• MLAG is the ability of switches to appear as a single switch at layer 2, so that bundles of links in the form of LAGs can be diversely connected to each switch and appear as one. LAGs are typically created North & South i.e. between host and switch, whereas MLAG is created and expanded in an East & West direction.