Queue Sets; Table 4: Ethernet Routing Switch 5500 Resource Sharing - Nortel 5530 Engineering Manual

Filters and QoS Configuration for ERS 5500
Technical Configuration Guide

4. Queue Sets

Prior to software release 4.0, the Ethernet Routing Switch 5500 supported a single queue set with
eight queues, one absolute queue and seven WRR queues.
With the introduction of software release 4.0, eight different queue sets where made available.
Each queue set has different characteristics in regards to number of queues and service weights
allowing the user to select a queue set based on the user's particular needs. With eight queue
settings and three resource sharing options, the Ethernet Routing Switch 5500 supports a total of
24 different queues and buffer setting combinations. Prior to making any changes to the egress
queue, the buffer resource sharing feature must be enabled.
Resource Sharing
The three (3) possible resource sharing settings in version 4.0 or greater software release are
regular, large, and maximum. These settings allow the user to change the amount of buffer
which can be allocated or shared to any port. Note that the switch must be rebooted if any
changes are made.

Table 4: Ethernet Routing Switch 5500 Resource Sharing

Setting Description
Regular 1 port may use up to 16% of the buffers for a group of 12 ports.
Large 1 port may use up to 33% of the buffers for a group of 12 ports.
Maximum 1 port may use 100% of the buffers for a group of 12 ports.
Resource Sharing Commands
•
5520-24T-PWR(config)# qos agent buffer <large | maximum | regular>
The qos agent buffer <regular | large | maximum > command allows the user to specify
the level of resource sharing on the switch. This parameter is global and requires a reset
to activate a change. This command is in the CLI priv-exec mode.
•
5520-24T-PWR(config)# default qos agent buffer
The default qos agent buffer command sets the switches agent buffer back to a default
setting of regular. In order for this command to take affect, a reset of the switch must
occur. This command is in the CLI priv-exec mode.
Resource Sharing Recommendations
Nortel Networks recommends you use the default resource-sharing setting of regular. If
you change the setting, the resulting performance may increase for some ports, and at
times, decrease for other ports.
Generally speaking, smaller buffers achieve lower latency (RTT) but reduce the throughput ability
which is better for VoIP etc. and sensible jitter application.
You should use the Maximum resource sharing setting:
•
If you are using your 5520 for big file transfers (like backup of servers)
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