Enhanced Transmission Selection Configuration

Enhanced Transmission Selection (ETS) queuing provides for configuring two or more traffic class queues (transmit queue (TxQ)) to be allocated for bandwidth that will not be serviced until all non-ETS queues are empty. The firmware services non-ETS selection queues first using strict priority, based upon the priority assigned to the queue. Enhanced Transmission Selection queue contents are forwarded to a fair queue scheduler on a strict priority basis. The fair queue scheduler distributes the remaining bandwidth, after all non-Enhanced Transmission Selection queues are empty, based upon the bandwidth allocation configured for the Enhanced Transmission Selection queues.

Note

Enhanced Transmission Selection queuing is restricted to configurable queues. S- K- and 7100-Series modules support both configurable and non-configurable queues. Non-configurable queues are Low Latency Queues (LLQ). LLQs are labeled LLQ in the show cos port-config command display. See Low Latency Queuing for LLQ details.

Enhanced Transmission Selection traffic classes (TxQs) and bandwidth allocation are configured using the set cos port-config txq command.

Enhanced Transmission Selection (ETS) Queuing presents an Enhanced Transmission Selection queuing example. Priority queues 7, 6, and 5 are assigned traffic classes 7, 6, and 5, respectively. These non-ETS queues are serviced first by the strict priority scheduler based upon priority.

Enhanced Transmission Selection (ETS) Queuing

802.1 priorities 0 - 4 are configured for Enhanced Transmission Selection queuing. Priorities 4 and 3 are assigned to traffic class 4. Priorities 0, 1, and 2 are assigned to traffic class 2. If all non-ETS queues are empty and there is remaining bandwidth, traffic classes 4 and 2 will be serviced using weighted fair queue scheduling. Based upon Enhanced Transmission Selection bandwidth allocation, the weighted fair queue scheduler will service traffic class 4 at 70 percent and traffic class 2 at 30 percent of remaining bandwidth. Within each traffic class group (4 and 2 in this example), each priority is serviced based on a strict priority scheduler.

Note

The 7100-Series supports up to two ETS groups (traffic classes).

This example shows how to create a CoS transmit queue port group entry named testTxq with a:

• Port Group ID of 2
• Port Type ID of 0 (7100-Series)
• Port Type ID of 1 (S-, K-Series)

The example assigns ETS groups to an 8 queue 7100-Series device or and 11 queue S- K-Series device, followed by allocation of ETS bandwidth to the assigned groups. Using the enhanced-groups option of the set cos port-config txq command, ETS group to queue assignment is:

• Group 2 to queues 0, 1, and 2
• Group 4 to queues 3 and 4

Using the enhanced-percentage option of the set cos port-config txq command, the assigned ETS bandwidth allocation is:

• 30 percent to group 2
• 70 percent to group 4

  7100-Series(rw)->set cos port-config txq 2.0 name testTxq enhanced-groups 2,2,2,4,4,0,0,0 enhanced-percentage 0,30,0,70,0,0,0,0
  S-K-Series(rw)->set cos port-config txq 2.1 name testTxq enhanced-groups 2,2,2,4,4,0,0,0,0,0,0 enhanced-percentage 0,30,0,70,0,0,0,0

Use the Enhanced Transmission Selection configuration TLV to advertise this ETS configuration to the peer:

System(rw)->set lldp port tx-tlv enhanced-trans-config

Use the Enhanced Transmission Selection recommendation TLV to recommend that the peer use this ETS configuration:

System(rw)->set lldp port tx-tlv enhanced-trans-rec