Administrator Guide

The benefit of supporting a dynamic LAG is that the Aggregator's server-facing ports can toggle between
participating in the LAG or acting as individual ports based on the dynamic information exchanged with a
server NIC. LACP supports the exchange of messages on a link to allow their LACP instances to:
• Reach agreement on the identity of the LAG to which the link belongs.
• Attach the link to that LAG.
• Enable the transmission and reception functions in an orderly manner.
• Detach the link from the LAG if one of the partner stops responding.
LACP Modes
The Aggregator supports only LACP active mode as the default mode of operation. In active mode, a port
interface is considered to be not part of a LAG but rather in an active negotiating state.
A port in active mode automatically initiates negotiations with other ports by sending LACP packets. If you
configure server-facing ports for LACP-based NIC teaming, LACP negotiations take place to aggregate the
port in a dynamic LAG. If you do not configure server-facing ports for LACP-based NIC teaming, a port is
treated as an individual port in active negotiating state.
Auto-Configured LACP Timeout
LACP PDUs are exchanged between port channel (LAG) interfaces to maintain LACP sessions. LACP PDUs are
transmitted at a slow or fast transmission rate, depending on the LACP timeout value configured on the
partner system.
The timeout value is the amount of time that a LAG interface waits for a PDU from the partner system before
bringing the LACP session down. The default timeout is long-timeout (30 seconds) and is not user-
configurable on the Aggregator.
Link Aggregation Control Protocol
(LACP)
The commands for Dell Networks’s implementation of the link aggregation control protocol (LACP) for
creating dynamic link aggregation groups (LAGs) — known as port-channels in the Dell Networking OS — are
provided in the following sections.
NOTE
: For static LAG commands, refer to the chapter), based on the standards specified in the IEEE 802.3
Carrier sense multiple access with collision detection (CSMA/CD) access method and physical layer
specifications.
Configuration Tasks for Port Channel Interfaces
To configure a port channel (LAG), use the commands similar to those found in physical interfaces. By default,
no port channels are configured in the startup configuration. In VLT mode, port channel configurations are
allowed in the startup configuration.
These are the mandatory and optional configuration tasks:
Link Aggregation 528