Specifications

Chapter 5. IBM System Networking RackSwitch implementation 183
In Example 5-32 on page 181, you can see that the current switch (ACC-1) is the root for
VLAN 10 and the ACC-2 switch is the root for VLAN 20, by checking the MAC addresses of
the root bridge for each STG.
You can find the MAC address of the current root by running show system:
ACC-1#show system | include MAC
MAC address: 08:17:f4:34:4d:00 IP (If 10) address: 10.0.10.2
MGMT-A Port MAC Address: 08:17:f4:34:4d:fe
MGMT-B Port MAC Address: 08:17:f4:34:4d:ef
ACC-2#show system | include MAC
MAC address: 08:17:f4:34:4c:00 IP (If 10) address: 10.0.10.3
MGMT-A Port MAC Address: 08:17:f4:34:4c:fe
MGMT-B Port MAC Address: 08:17:f4:34:4c:ef
ACC-2#
5.2.4 Quality of Service
A Quality of Service (QoS) implementation in IBM Networking OS is not in the scope of the
reference architecture used in this book. However, a summary of configuration topics and
commands is presented for completeness.
QoS commands configure the 802.1p priority value and DiffServ Code Point value of
incoming packets, so you can differentiate between various types of traffic, and provide
different priority levels.
802.1p configuration
This feature provides the switch the capability to filter IP packets based on the 802.1p bits in
the packet's VLAN header. The 802.1p bits specify the priority that you should give to the
packets while forwarding them. The packets with a higher (non-zero) priority bits are given
forwarding preference over packets with numerically lower priority bits value.
You can use the following commands to complete the configuration:
򐂰 Run qos transmit-queue mapping <priority (0-7)> <COSq number> to map the 802.1p
priority of to the Class of Service queue (COSq) priority. Enter the 802.1p priority value
(0 - 7), followed by the Class of Service queue that handles the matching traffic.
򐂰 Run qos transmit-queue weight-cos <COSq number> <weight (0-15)> to configure the
weight of the selected Class of Service queue (COSq). Enter the queue number (0 - 1),
followed by the scheduling weight (0 - 15).
򐂰 Run show qos transmit-queue to show the current 802.1p parameters.
DSCP configuration
The following commands map the DiffServ Code Point (DSCP) value of incoming packets to
a new value or to an 802.1p priority value:
򐂰 Run qos dscp dscp-mapping <DSCP (0-63)> <new DSCP (0-63)> to map the initial
DiffServ Code Point (DSCP) value to a new value. Enter the DSCP value (0 - 63) of the
incoming packets, followed by the new value.
򐂰 Run qos dscp dot1p-mapping <DSCP (0-63)> <priority (0-7)> to map the DiffServ
Code point value to an 802.1p priority value. Enter the DSCP value, followed by the
corresponding 802.1p value.