Multi-Chassis Link Aggregation Group (M-LAG) is a high-availability technology on Huawei

CloudEngine (CE) series switches, where two switches appear as a single logical device to

downstream devices. The peer-link between the M-LAG peers synchronizes critical information to

ensure seamless failover if one device fails. Let’s evaluate the entries:

A. MAC Address Entries: MAC address tables map device MACs to ports. In M-LAG, synchronizing

MAC entries ensures that both switches know the location of connected devices. If one switch fails,

the surviving switch can forward Layer 2 traffic without relearning MAC addresses, preventing

disruptions. Required.

B. Routing Entries: Routing entries (e.g., OSPF or BGP routes) are maintained at Layer 3 and typically

synchronized via routing protocols, not M-LAG peer-link packets. M-LAG operates at Layer 2, and

while Layer 3 can be overlaid (e.g., with VXLAN), routing table synchronization is not a standard M-

LAG requirement. Not Required.

C. IGMP Entries: IGMP (Internet Group Management Protocol) entries track multicast group

memberships. While useful for multicast traffic, they are not critical for basic unicast traffic

forwarding in M-LAG failover scenarios. Huawei documentation indicates IGMP synchronization is

optional and context-specific, not mandatory for general traffic continuity. Not Required.

D. ARP Entries: ARP (Address Resolution Protocol) entries map IP addresses to MAC addresses,

crucial for Layer 2/Layer 3 communication. Synchronizing ARP entries ensures the surviving switch

can resolve IP-to-MAC mappings post-failover, avoiding ARP flooding or traffic loss. Required.

Thus, A (MAC address entries) and D (ARP entries) are essential for M-LAG synchronization to

maintain traffic forwarding during failover, per Huawei CE switch M-LAG design.

Reference: Huawei CloudEngine Series Switch Configuration Guide – M-LAG Section; HCIP-Data

Center Network Training – High Availability Technologies.