3Com Switch 8807, Configuration Manual

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184 C
HAPTER
22: Q
O
S C
ONFIGURATION
sent can those in lower priority queue be sent. This manner of putting key-service
packets into high priority queue and non-key service packets into low priority
queue does ensure that key-service packets are sent first, while non-key service
packets are sent during the interval when no key-service packets needs to be
processed.
SP algorithm also has its disadvantages: If high priority queues are full, then
packets from the low priority queues may not be forwarded.
2 WRR algorithm
Each port supports eight outbound queues except that port of the
GV48D/GP48D/XP4 non-wire-speed card only supports four queues. In WRR
mode, the system processes the queues by turn, so every queue can have a service
period.
See the case where the port supports eight outbound queues. Every queue is
assigned with a weight value (respectively numbered as w7, w6, w5, w4, w3, w2,
w1 and w0), which indicates the weight in obtaining resources. For a 100 Mbps
port, the weight values are set as 50, 30, 10, 10, 50, 30, 10 and 10
(corresponding respectively to w7, w6, w5, w4, w3, w2, w1 and w0). The even
the queue with the lowest priority can be allocated with a 5 Mbps bandwidth.
Another merit for WRR algorithm: Though the queues are scheduled by turn, they
are not configured with fixed time quantum. If a queue has no packets, the system
immediately schedules the next queue. Then bandwidth resources can be fully
utilized.
Traffic mirroring
Traffic mirroring duplicates specified packets to CPU for network test and
troubleshooting.
Port mirroring
Port mirroring duplicates all packets at a specified port to the monitoring port for
network test and troubleshooting.
Flow-based traffic statistics
The system can make traffic statistics based on flow for further analysis.
Introduction to QoS
Configuration Based
on Port Groups
To help you configure the same QACL rule on multiple ports, Switch 8800 Family
series switches implement the function of configuring QACL based on port
groups. You only need to create a port group and configure QACL for the port
group. The configuration is valid for all the member ports in the port group, thus
avoiding configuring QACL on multiple ports respectively. After a port group is
configured, the QACL configuration of all the member ports in the port group
keeps the same all the time.
Configuring QoS Based
on Port Groups
Perform the following configuration to configure QoS based on port groups
(assume that the flow template and ACL have been defined):