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Uplink LAG
When the Aggregator power is on, all uplink ports are configured in a single LAG (LAG 128).
Server-Facing LAGs
Server-facing ports are configured as individual ports by default. If you configure a server NIC in standalone, stacking, or VLT
mode for LACP-based NIC teaming, server-facing ports are automatically configured as part of dynamic LAGs. The LAG range 1
to 127 is reserved for server-facing LAGs.
After the Aggregator receives LACPDU from server-facing ports, the information embedded in the LACPDU (remote-system
ID and port key) is used to form a server-facing LAG. The LAG/port-channel 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)
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:
● Reassigning an Interface to a New Port Channel (optional)
Link Aggregation
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