Dell PowerEdge FX2/FX2s - Manual (Page 120)

number is assigned based on the first available number in the range from 1 to 127. For each unique
remote system-id and port-key combination, a new LAG is formed and the port automatically becomes a
member of the LAG.
All ports with the same combination of system ID and port key automatically become members of the
same LAG. Ports are automatically removed from the LAG if the NIC teaming configuration on a server-
facing port changes or if the port goes operationally down. Also, a server-facing LAG is removed when
the last port member is removed from the LAG.
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)
This chapter contains 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 Operating System (OS).
NOTE: For static LAG commands, refer to the Interfaces 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:
120 Link Aggregation