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Examples: Configuring CoS on Aggregated Interfaces

This example illustrates how CoS scheduler parameters are configured and applied to aggregated interfaces.

Applying Scaling Formula to Absolute Rates

Configure queues as follows when the total speed of member link interfaces is 100 Mbps (the available bandwidth is 100 Mbps):

[edit class-of-service]schedulers {be {transmit-rate 10m;}af {transmit-rate 20m;}ef {transmit-rate 80m;}nc {transmit-rate 30m;}}

The total configured transmit rates of the aggregated interface is 10m + 20m + 80m + 30m = 140 Mbps, meaning the transmit rate is overconfigured by 40 percent. Therefore, the software scales down the configuration to match the 100 Mbps of available bandwidth, as follows:

be = (10/140) * 100 = 7 percent of 100 Mbps = 7 Mbpsaf = (20/140) * 100 = 14 percent of 100 Mbps = 14 Mbpsef = (80/140) * 100 = 57 percent of 100 Mbps = 57 Mbpsnc = (30/140) * 100 = 21 percent of 100 Mbps = 21 Mbps

Applying Scaling Formula to Mixture of Percent and Absolute Rates

Configure the following mixture of percent and absolute rates:

[edit class-of-service]schedulers {be {transmit-rate 20 percent;}af {transmit-rate 40 percent;}ef {transmit-rate 150m;}nc {transmit-rate 10 percent;}}

Assuming 300 Mbps of available bandwidth, the configured percentages correlate with the following absolute rates:

schedulers {be {transmit-rate 60m;}af {transmit-rate 120m;}ef {transmit-rate 150m;}nc {transmit-rate 30m;}}

The software scales the bandwidth allocation as follows:

be = (60/360) * 100 = 17 percent of 300 Mbps = 51 Mbpsaf = (120/360) * 100 = 33 percent of 300 Mbps = 99 Mbpsef = (150/360) * 100 = 42 percent of 300 Mbps = 126 Mbpsnc = (30/360) * 100 = 8 percent of 300 Mbps = 24 Mbps

Configuring an Aggregated Ethernet Interface

Configure an aggregated Ethernet interface with the following scheduler map:

[edit class-of-service]scheduler-maps {aggregated-sched {forwarding-class be scheduler be;forwarding-class af scheduler af;forwarding-class ef scheduler ef;forwarding-class nc scheduler nc;}}schedulers {be {transmit-rate percent 10;buffer-size percent 25;}af {transmit-rate percent 20;buffer-size percent 25;}ef {transmit-rate 80m;buffer-size percent 25;}nc {transmit-rate percent 30;buffer-size percent 25;}}

In this case, the transmission rate for the member link scheduler map is as follows:

• be—7 percent
• af—14 percent
• ef—57 percent
• nc—21 percent

If you add a Fast Ethernet interface to the aggregate, the aggregate bandwidth is 200 Mbps, and the transmission rate for the member link scheduler map is as follows:

• be—10 percent
• af—20 percent
• ef—40 percent
• nc—30 percent

Published: 2010-04-15

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