The following guidelines apply to the ETH-BN configuration:
In a committed information rate (CIR) loop, scheduling is packet-based round robin with weight 1. This scheduling applies to SAP and port queues, and between SAP aggregates and network aggregates when the node is operating in the SAP scheduler mode. Refer to the 7210 SAS-Mxp, R6, R12, S, Sx, T Quality of Service Guide for more information about schedulers.
When the node is operating in the port-scheduler-mode, the access egress QoS policy is attached to the access port. Users can configure queue rates for the access egress QoS policy using either the rate or percent-rate command. The percent-rate command configures queue rates as a percentage of the port shaper rate that is currently in effect.
When using the ETH-BN feature, Nokia recommends using the percent-rate command to configure queue rates in the access egress QoS policy so that the system can update queue rates based on the ETH-BN port egress rate changes and oversubscription of the port scheduler is avoided.
To implement port-level policy attachment changes or queue mode changes for access egress or network queue policies, Nokia recommends shutting down the ports to which the policy is attached and waiting until the queues clear before modifying the QoS policy.
When modifying the queue mode on a queue for a SAP egress QoS policy that is already attached to SAPs, or when modifying a SAP egress QoS policy attached to any SAP, Nokia recommends shutting down the SAPs that the policy is attached to and waiting until the queues clear before modifying the QoS policy. Use the show pools access-egress and network-egress commands to check for zero queue depth.
Egress rate changes because of ETH-BN may lead to CIR oversubscription, which is not supported on the 7210 SAS-Mxp, 7210 SAS-R6, and 7210 SAS-R12. Use the following guidelines to avoid CIR oversubscription:
To use SAP scheduler mode for access or hybrid port mode, configure the CIR on queues in the SAP egress policy and SAP aggregates or network aggregates based on the lower ETH-BN expected rate, and ensure that the CIR is not oversubscribed. A change in the ETH-BN rate will not cause CIR oversubscription because the values are based on the lowest ETH-BN rate.
After an ETH-BN rate change is detected, update the QoS policy CIR and PIR values, and SAP and network aggregate rates from the management station to prevent CIR oversubscription.