Technical data

BLADE OS 5.1 Application Guide
BMD00136, November 2009 Chapter 4: Ports and Trunking
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A port’s Link Aggregation Identifier (LAG ID) determines how the port can be aggregated. The
Link Aggregation ID (LAG ID) is constructed mainly from the system ID and the port’s admin key,
as follows:
System ID is an integer value based on the switch’s MAC address and the system priority assigned
in the CLI.
Admin key
A port’s Admin key is an integer value (1-65535) that you can configure in the CLI. Each switch
port that participates in the same LACP trunk group must have the same admin key value. The
Admin key is local significant, which means the partner switch does not need to use the same
Admin key value.
For example, consider two switches, an Actor (the G8000) and a Partner (another switch), as shown
in Table 8.
In the configuration shown in Table 8, Actor switch port 7 and port 8 aggregate to form an LACP
trunk group with Partner switch port 1 and port 2.
LACP automatically determines which member links can be aggregated and then aggregates them.
It provides for the controlled addition and removal of physical links for the link aggregation.
Each port on the switch can have one of the following LACP modes.
 off (default)
The user can configure this port in to a regular static trunk group.
 active
The port is capable of forming an LACP trunk. This port sends LACPDU packets to partner
system ports.
 passive
The port is capable of forming an LACP trunk. This port only responds to the LACPDU
packets sent from an LACP active port.
Each active LACP port transmits LACP data units (LACPDUs), while each passive LACP
port listens for LACPDUs. During LACP negotiation, the admin key is exchanged. The LACP
trunk group is enabled as long as the information matches at both ends of the link. If the admin key
value changes for a port at either end of the link, that port’s association with the LACP trunk group
is lost.
Table 8 Actor vs. Partner LACP configuration
Actor Switch Partner Switch 1
Port 7 (admin key = 100) Port 1 (admin key = 50)
Port 8 (admin key = 100) Port 2 (admin key = 50)