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Example: Configuring a Large Delay Buffer on a Channelized T1 Interface

This example shows how to configure a large delay buffer on a channelized T1 interface to help slower interfaces avoid congestion and packet dropping when they receive large bursts of traffic.


Before you begin, enable the large buffer feature on the channelized T1/E1 PIM and then configure a buffer size for each queue in the CoS scheduler. See Scheduler Buffer Size Overview.


On devices, you can configure large delay buffers on channelized T1/E1 interfaces. Each channelized T1/E1 interface can be configured as a single clear channel, or for channelized (NxDS0) operation, where N denotes channels 1 to 24 for a T1 interface and channels 1 to 32 for an E1 interface.

In this example, you specify a queue buffer of 30 percent in scheduler be-scheduler and associate the scheduler to a defined forwarding class be-class using scheduler map large-buf-sched-map. Finally, you apply the scheduler map to channelized T1 interface t1-3/0/0.



CLI Quick Configuration

To quickly configure this example, copy the following commands, paste them into a text file, remove any line breaks, change any details necessary to match your network configuration, copy and paste the commands into the CLI at the [edit] hierarchy level, and then enter commit from the configuration mode.

Step-by-Step Procedure

The following example requires you to navigate various levels in the configuration hierarchy. For instructions on how to do that, see Using the CLI Editor in Configuration Mode in the Junos OS CLI User Guide.

To configure a large delay buffer on a channelized T1 interface:

  1. Enable the large buffer size feature on the channelized T1 interface.

  2. Create best-effort traffic and specify a buffer size.

  3. Configure the scheduler map to associate schedulers with defined forwarding classes.

  4. Apply the scheduler map to the channelized T1 interface.


From configuration mode, confirm your configuration by entering the show class-of-service and show chassis commands. If the output does not display the intended configuration, repeat the configuration instructions in this example to correct it.

If you are done configuring the device, enter commit from configuration mode.


Verifying Large Delay Buffers Configuration


Verify that the large delay buffers are configured properly.


From configuration mode, enter the show class-of-service and show chassis commands.