Technical data

DATA CENTER and CAMPUS NETWORKS DEPLOYMENT GUIDE
Deploying Brocade Networks with Microsoft Lync Server 2010 21 of 52
Configuring QoS
• To enable DSCP, enter the this simple command, which is all that is necessary for configuration to
honor DSCP on Brocade switches:
FastIron(config-if-e1000-11)trust dscp
• To change the DSCP value within Group Policy, refer to the Microsoft configuration guide. To assign
traffic that matches the ACL to a hardware forward queue and re-mark the packets that match the ACL
with the 802.p priority, use this command:
FastIron(config-if-e1000-11) access-list 101 permit ip any dscp-matching 46 802.1p-
priority-marking 7
• To change the DSCP internal forwarding priority mappings for all the DSCP ranges, enter commands
such as the following at the global CONFIG level of the Command Line Interface (CLI):
FastIron(config)#qos-tos map dscp-priority 48 to 7
This tells the switch that for any packet entering the switch with a DSCP value of 48, you should assign it to a
CoS (internal forwarding queue) value of 7 (the highest priority).
Scheduling
Scheduling is the process of mapping a packet to an internal forwarding queue based on its QoS information and
servicing the queues according to a mechanism.
QoS Queuing Methods
The following QoS queuing methods are supported in all IronWare releases for the Brocade FastIron
®
and TurboIron
®
devices:
• Weighted Round Robin (WRR). WRR ensures that all queues are serviced during each cycle. A
weighted fair queuing algorithm is used to rotate service among the eight queues on the Brocade
FastIron and TurboIron devices. The rotation is based on the weights you assign to each queue. This
method rotates service among the queues, forwarding a specific number of packets in one queue
before moving on to the next one. WRR is the default queuing method, and it uses a default set of
queue weights. The number of packets serviced during each visit to a queue depends on the
percentages you configure for the queues. The software automatically converts the percentages you
specify into weights for the queues.
Table 2. Default Minimum Bandwidth Percentages on Brocade Ethernet Switches Using WRR.
Queue
Without Jumbo Frames
With Jumbo Frames
QoS p7
75%
44%
QoS p6
7%
8%
QoS p5
3%
8%
QoS p4
3%
8%
QoS p3
3%
8%
QoS p2
3%
8%
QoS p1
3%
8%
QoS p0
3%
8%
These priorities can be changed. If you would like to change the recommended default configuration, please
refer to the configuration guide.