Management and Configuration Guide K/KA/KB.15.15

7 Link Aggregation Control Protocol-Multi-Active Detection
LACP configuration
The following command defines whether LACP is enabled on a port, and whether it is in active or
passive mode when enabled. When LACP is enabled and active, the port sends LACP packets and
listens to them. When LACP is enabled and passive, the port sends LACP packets only if it is spoken
to. When LACP is disabled, the port ignores LACP packets. If the command is issued without a
mode parameter, 'active' is assumed. During dynamic link aggregation using LACP, ports with the
same key are aggregated as a single trunk. MAD passthrough applies only to trunks and not to
physical ports.
Syntax
[no]interface <port-list> lacp [mad-passthrough
[enable|disable]|active|passive|key <key>]
Viewing LACP-MAD configuration
Syntax
show lacp [counters [<port-list>] | local [<port-list>] |peer
[<port-list>] | distributed | mad-passthrough [counters [<port-list>]]]
Show LACP-MAD passthrough configuration on LACP trunks.
Syntax
show lacp mad-passthrough counters [<port-list>]
Show LACP-MAD passthough counters on ports
Clear all LACP statistics
Syntax
clear lacp statistics
Clear all LACP statistics including MAD passthrough counters. Resets LACP packets sent and
received on all ports.
LACP-MAD Operations
Link Aggregation Control Protocol-Multi-Active Detection (LACP-MAD) is a detection mechanism
deployed by switches to recover from a breakup of the Intelligent Resilient Framework (IRF) stack
due to link or other failure.
LACP-MAD is implemented by sending extended LACP data units (LACPDUs) with a type length
value (TLV) that conveys the active ID of an IRF virtual device. The active ID is identical to the
member ID of the master and is thus unique to the IRF virtual device. When LACP MAD detection
is enabled, the members exchange their active IDs by sending extended LACPDUs.
• When the IRF virtual device operates normally, the active IDs in the extended LACPDUs sent
by all members are the same, indicating that there is no multi-active collision.
• When there is a breakup in the IRF stack, the active IDs in the extended LACPDUs sent by the
members in different IRF virtual devices are different, indicating that there are multi-active
collisions.
LACP-MAD passthrough helps IRF-capable devices detect multi-access and take corrective action.
These devices do not initiate transmission of LACP-MAD frames or participate in any MAD decision
LACP configuration 267