Configuring Load Rebalancing for 802.3ad Link Aggregation Groups
You can configure
the parameters that the system uses to rebalance the links in a LAG.
You can also configure the system to dynamically rebalance the links
in the LAG.
Tasks to configure load rebalancing are:
Configuring Load–Rebalancing Parameters
To configure load–rebalancing
parameters:
- Specify the LAG interface.
- host1(config)#interface lag lg1
- Configure parameters that guide the system to rebalance.
- host1(config-if)#load-rebalance period 120
start-threshold 20 percent stop-threshold
100 percent maximum-improvement 300
This example specifies that the system
rebalance within 120 seconds, can accept imbalance in the LAG in the
range 20–100 percent, and can move 300 subscribers to other
ports during that time.
Table 1 describes
the load balancing algorithm parameters that you can configure.
Table 1: Load Balancing
Algorithm Parameters
|
Keyword
|
Description
|
|
period
|
Specifies the time period for rebalancing. For example,
a period of 120 specifies that rebalancing occurs once every 2 minutes.
|
|
start-threshold
|
Specifies the amount of imbalance in the LAG that triggers
the algorithm to start rebalancing. The default is 0 percent. Optionally,
you can specify one of the following units of measure:
-
percent—Specifies that
the amount of imbalance is measured as a percentage of the average
load per link. The range is 0–100 percent.
For example, the average load per link in a LAG is 500. Specifying start-threshold 5 percent indicates that the algorithm
rebalances any link that deviates from the average load per link by
25 (5 percent of 500).
-
subscribers—Specifies
that the amount of imbalance is measured by the number of subscribers
from the average subscriber count in the LAG. The range is 0–10000.
For example, specifying start-threshold 20 subscribers indicates that the algorithm rebalances any link with a subscriber
count that differs from the average subscriber count by more than
20.
|
|
stop-threshold
|
Specifies the amount of imbalance in the LAG that triggers
the algorithm to stop rebalancing. The algorithm continues rebalancing
until this value is reached. The default is 0 percent. Optionally,
you can specify one of the following units of measure:
-
percent—Specifies that
the amount of imbalance is measured as a percentage of the average
load per link. The range is 0–100 percent.
For example, the average load per link in a LAG is 500. Specifying
the stop-threshold 2 percent command indicates
that the algorithm stops within 10 of 500 (2 percent of 500). In this
case, the algorithm stops when the links are at 510 and 490.
-
subscribers—Specifies
that the amount of imbalance is measured by the number of subscribers.
The range is 0–10000.
For example, specifying stop-threshold 100 subscribers indicates that the algorithm continues until each link in the LAG
is within 100 subscribers of the average subscriber count.
|
|
maximum- improvement
|
Specifies the maximum number of links to rebalance in
the LAG per period. The default is 100 percent. Optionally, you can
specify one of the following units of measure:
-
percent—Specifies that
the maximum number of links is measured as a percentage of the total
links. The range is 0–100 percent.
For example, specifying maximum-improvement 1 percent indicates that the algorithm rebalances 10 links per period (1 percent
of 1000).
-
subscribers—Specifies
that the maximum number of links is measured by the number of subscribers.
The range is 0–10000 subscribers.
For example, specifying maximum-improvement 40
subscribers indicates that the algorithm rebalances
40 subscribers per period.
|
Configuring the System to Dynamically Rebalance the LAG
To configure the system
to dynamically rebalance the LAG:
- Specify the LAG interface.
- host1(config)#interface lag lg1
- Issue the load balance command with no keywords:
- host1(config-if)#load-rebalance