Administrator Guide

Uplink LAG
When the Aggregator power is on, all uplink ports are congured in a single LAG (LAG 128).
Server-Facing LAGs
Server-facing ports are congured as individual ports by default. If you congure a server NIC in standalone, stacking, or VLT mode
for LACP-based NIC teaming, server-facing ports are automatically congured 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 rst 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 conguration 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 benet 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 congure server-facing
ports for LACP-based NIC teaming, LACP negotiations take place to aggregate the port in a dynamic LAG. If you do not congure
server-facing ports for LACP-based NIC teaming, a port is treated as an individual port in active negotiating state.
Auto-Congured 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 congured 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-congurable on the Aggregator.
Link Aggregation
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