Administrator Guide

Dell Networking W-Series ArubaOS 6.4.x| User Guide Link Aggregation Control Protocol | 225
Chapter 6
Link Aggregation Control Protocol
The ArubaOS implementation of Link Aggregation Control Protocol (LACP) is based on the standards specified
in 802.3ad. LACP provides a standardized means for exchanging information, with partner systems, to form a
Link Aggregation Group (LAG). LACP avoids port channel misconfiguration.
Two devices (actor and partner) exchange LACP Data Units (DUs) when forming a LAG. Once multiple ports in
the system have the same actor system ID, actor key, partner system ID, and partner key, they belong to the
same LAG.
The maximum number of supported port-channels is eight. With the introduction of LACP, this number
remains the same. A port-channel group (LAG) is created either statically or dynamically through LACP. This
chapter contains the following topics:
l Understanding LACP Best Practices and Exceptions on page 225
l Configuring LACP on page 226
l LACP Sample Configuration on page 227
For information on configuring LACP on W-AP220 Series and W-AP270 Series access points, see Link Aggregation
Support on W-AP220 Series and W-AP270 Series on page 618
Understanding LACP Best Practices and Exceptions
l LACP is disabled by default.
l LACP depends on periodical Tx/Rx of LACP Data Units (LACPDUs). Any failure is noticed immediately and
that port is removed from the LAG.
l The maximum LAG supported per system is eight groups; each group can be created statically or through
LACP.
l Each LAG can have up to eight member ports.
l The LAG group identification (ID) range is 0–7 for both static (port-channel) and LACP groups.
l When a port is added to a LACP LAG, it inherits the port-channel’s properties such as, VLAN membership,
trunk status, and so on.
l When a port is added to a LACP LAG, the port’s property (like speed) is compared to the existing port
property. If there is a mismatch, the command is rejected.
l The LACP commands cannot be configured on a port that is already a member of a static port-channel.
Similarly, if the group assigned in the command lacp group <number> already contains static port
members, the command is rejected.
l The port uses the group number as its actor admin key.
l All ports use long timeout values (90 seconds) by default.
l The output of the command show interface port-channel now indicates if the LAG is created by LACP
(dynamic) or static configuration. If the LAG is created through LACP, you cannot add or delete any ports
under that port channel. All other commands are allowed.