What is MLAG network?

Hello Phany,

Have a good day.

M-LAG implements link aggregation among multiple devices. One device is connected to two devices through M-LAG to provide device-level link reliability.

On Layer 2, M-LAG can be considered as a horizontal virtualization technology, which virtualizes two physical devices into a single Layer 2 logical device. M-LAG prevents loops on a Layer 2 network and implements redundancy, without performing laborious spanning tree protocol configuration. M-LAG greatly simplifies the network and configuration. Compared with the traditional xSTP loop prevention mechanism, M-LAG provides a clearer logical topology and higher link efficiency.

Figure 5-3 M-LAG-based physical topology and Layer 2 as well as Layer 3 logical topologies

In Figure 5-3, the two M-LAG switches provide M-LAG interfaces for Layer 2 service access. A peer-link is configured between the two switches to exchange M-LAG packets and forward horizontal service traffic between the switches. In the Layer 3 logical topology, the two switches are two independent devices, can be managed by independent NMSs, and function as independent OSPF nodes. In addition, M-LAG supports preferential forwarding of local traffic, minimizing east-to-west traffic between the two switches. M-LAG supports dual-active detection (DAD). The two M-LAG devices are independent, so the in-band or out-of-band IP reachability detection can be used for DAD, without requiring additional cabling.

Deployment Scheme

• Scheme 1: Aggregation switches set up an M-LAG system.

M-LAG enables a loop-free logical network between aggregation and access switches, making STP deployment unnecessary. Two aggregation switches are configured to set up an M-LAG system and the link between the switches is configured as a peer-link. The ports on the two aggregation switches connected to the same access switch set up an inter-chassis Eth-Trunk.

Figure 5-4 Deploying M-LAG on aggregation switches

M-LAG provides a clearer logical topology and higher link efficiency than the traditional STP loop prevention mechanism. M-LAG devices have independent control and management planes and use the same protocol for information synchronization. M-LAG offers higher reliability than stack. Additionally, M-LAG devices can be upgraded independently, facilitating device maintenance.

• Scheme 2: Access switches set up an M-LAG system.

M-LAG also applies to scenarios where a server is dual-homed to two access switches with two NICs working in active-active mode. When a server is dual-homed to two access switches, the two NICs on the server use the same MAC address and implement flow-based load balancing. Therefore, in an M-LAG system, the ports on the two access switches connected to the server are configured as an Eth-Trunk, and MAC addresses and ARP entries of the two ports are synchronized between the two ports. Deploying M-LAG on access switches

Scheme Characteristics

M-LAG technology is essentially a control plane virtualization technology. Unlike stack technology, M-LAG only needs to synchronize information related to interfaces and entries, not all device information. This makes the control plane coupling of M-LAG much looser than that of stack. Some defects in stack technology are eased in M-LAG, including the three major issues facing stack, as follows:

Reliability issues: M-LAG does not need to synchronize all device information but only some protocol plane information, ensuring higher reliability than stack.

Maintenance issues: Two M-LAG devices can be upgraded independently. Only the protocol planes are coupled, shortening the service interruption time.

Limited scalability: M-LAG aims to solve the access-side multipath problem and typically works with routing or some large Layer 2 technologies to implement network-side multipath forwarding.

Thank you.

Hi friend!

The user-side device (switch or host) connects to SwitchA and SwitchB through M-LAG to constitute a dual-active system. SwitchA and SwitchB then forward traffic together to ensure network reliability.
Thanks!

Hi Phany, 

Multichassis Link Aggregation Group (M-LAG) implements link aggregation among multiple devices. In a dual-active system, one device is connected to two devices through M-LAG to achieve device-level link reliability.

For more information, please refer to https://support.huawei.com/hedex/hdx.do?docid=EDOC1100136524&id=EN-US_CONCEPT_0141112564&lang=en

I hope it helps!

When you implement MLAG to MLAG and if you don't use v-STP  ,
So if you wanna integrated to Juniper with MSTP so you need to disable stp on the peer-link .
I have done this config in Turkey.Also you need to do config same Bridge ID  at active and standby device.