Asr 5000 System Administration Guide, Staros Release 21.1 - Cisco ASR 5000 Administration Manual

System Settings
Use the following command to add a port as a member of the link aggregation group number N only if the
master port is assigned. Otherwise, it is added to the group when the master port is assigned:
port ethernet slot#/port#
link-aggregation member group N
exit
The VPN can only bind the master port, and a VLAN can only be created on the master port. A failure
Important
message is returned if you attempt to bind to a link aggregation member port.
Two redundant line cards and their controlling packet services card function as a system; this allows loopback
addressing between vertical slots. Each system that participates in link aggregation has a unique system ID
that consists of a two-byte priority (where the lowest number [0] has the highest priority) and a six-byte MAC
address derived from the first port's MAC address.
The following command sets the system priority used to form the system ID. P can be one of the following
options:
• a hexadecimal number in the range [0x0000..0xFFFF, default = 0x8000]
• an integer from 0 through 65535
• auto
card slot#
link-aggregation system-priority P
Ports in a system are assigned keys. The group number maps directly to the key, whereupon only ports with
the same key can be aggregated. Ports on each side of the link use a different aggregation key.
The system ID, port key and port ID of two peers form the Link Aggregation Group Identifier (LAGID). You
can aggregate links having the same LAGID. Systems are often configured initially with each port in its own
aggregation (requiring a separate key per port), or with all ports in the same aggregation (a single key for all
ports). Negotiation via LACP would qualify the actual aggregation.
Systems exchange information about system ID, port key and port ID with peers across the physical links
using LACP.
LACP packets are defined with the Slow Protocol format. Each system sends out its own ("actor") information
and its last received information about its peer ("partner") over the physical link.
Use the following commands to set the LACP parameters. LACP can run in active mode to send LACP packets
periodically, or in passive mode, in which it only responds to LACP packets it receives.
LACP can send packets at either a slow (30s) or fast (1s) rate. The defaults for this release are Active and
Slow; see the sample configuration below:
config
port ethernet slot#/port#
link-aggregation lacp { active | passive } [ rate { auto | fast | slow } | timeout { long | short } ]
Peers send out LACP packets when the state changes or if a difference is found from a received LACP packet
about its own state.
Corresponding ports on a QGLC or XGLC redundant pair cannot be active at the same time. Redundant ports
share the same MAC address, so after a failover is resolved, the original port rejoins the LAG.

ASR 5000 System Administration Guide, StarOS Release 21.1

Link Aggregation Control
77