example Qos implementation
Implementing the QoS feature in blade server chassis switches may be
necessary to prioritize the traffic from certain blades. For example, to
assign priorities to incoming traffic coming from each of 10 blades, admin-
istrators could assign default CoS values to the 10 internal ports of the
chassis switch that connects to the blade LAN on Motherboards (LOMs),
as shown in Figure 9.
Administrators could also assign default priority values for incoming
traffic on the six external ports, but typically they should designate all of
these ports with a common priority that allocates traffic to the best-effort
queue. They should enable the trust mode on all 16 ports so that if incom-
ing packets arrive with a CoS or DSCP value, the switch does not overwrite
these values with the default port setting.
For each egress port, the SP queues are defined starting from the
higher queue numbers; therefore, the higher CoS values are mapped to
higher queue numbers, as shown in Figure 10. The queues can be config-
ured using the parameters on the Global Queue Settings screen of the
Dell OpenManage Switch Administrator GUI, as shown in Figure 11. Queue
4 is defined as an SP queue, and weights are assigned to the three WRR
queues. With these settings, the traffic from blades 1 and 2 is assigned
to the SP queue, while traffic from the other blades is assigned using the
WRR algorithm to help ensure higher priority for higher CoS values.
Optimizing network traffic for blade servers
The advanced configuration options for the Dell PowerConnect 5316M
blade server chassis switch include MSTP for load balancing, QoS for prior-
ity management, and IGMP snooping for IP multicast traffic. Using these
capabilities enables administrators to optimize blade server data traffic
and enhance deployment flexibility in network infrastructures.
Surendra Bhat
is a test engineer senior analyst in the Enterprise System
Test Group at the Dell Bangalore Development Center. He has a bachelor’s
degree in Electronics Engineering from the University of Mumbai. His
interests include networking and storage technologies.
Saurabh Mallik
is a test engineer analyst in the Enterprise System Test
Group at the Dell Bangalore Development Center. He has a bachelor’s
degree in Electronics and Communications Engineering from the Peoples
Education Society Institute of Technology (PESIT).
Figure 9.
Example default CoS values used to assign incoming traffic
priorities for Dell PowerConnect 5316M internal ports
Port number
cos value
1
7
2
7
3
5
4
5
5
3
6
3
7
3
8
1
9
1
10
1
cos value
Queue
0
1
1
1
2
2
3
2
4
3
5
3
6
4
7
4
Figure 10.
Example CoS values mapped to queue numbers for the Dell
PowerConnect 5316M switch
Figure 11.
Example configuration using the Global Queue Settings
screen for the Dell PowerConnect 5316M switch
Queue
Priority
configuration
wrr
weight
wrr
bandwidth
1
Wrr
2
20%
2
Wrr
3
30%
3
Wrr
5
50%
4
SP
n/a
n/a
QUICK LINK
Dell PowerConnect 5316M User’s Guide:
support.dell.com/support/edocs/network/PC5316M
network and communications
DELL
POWER
SOLUTIONS |
May 2007
5
reprinted from
Dell Power Solutions,
May 2007. Copyright © 2007 dell inc. all rights reserved.
