3Com 8807 Configuration Manual page 193

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Configuring Traffic
Shaping
Configuring Traffic
Priority
retrieval. You can also assign a system index for it when delivering an ACL rule
with this command, but the index value may change while the system is running.
However, you are not recommended to assign a system index if not urgently
necessary.
tc-index index here is traffic policing index. If you configure the same index for
different ACL rules during setting traffic policing, then the sum of traffic shall be
limited by the traffic policing-related parameters predefined. For example, if CIR
(committed information rate) of the traffic that matches ACL1 is set to 10 kbps
and that for ACL2 to 10 kbps, and their traffic policing indexes are the same, then
the average rate of the traffic that matches ACL1 and ACL2 shall be limited to
10kbps.
When you specify the same tc-index for different traffics, the traffic
policing-related parameter settings must be consistent with each other. Otherwise,
the system will prompt an error.
See the corresponding Command Manual for details of the commands.
Traffic shaping controls the rate of outbound packets, to ensure they are sent at
relatively average rates. Traffic shaping measure tries to match packet transmission
rate with the capacity of downstream devices. Its major difference from traffic
policing is: Traffic shaping buffers packets at over-threshold rates to make them
sent at average rates, while traffic policing drops excessive packets. Therefore,
traffic shaping may increase transmission delay, but not for traffic policing.
Perform the following configurations in Ethernet port view.
Table 166 Configure traffic shaping
Operation
Configure traffic shaping
Remove traffic shaping setting
The switch supports traffic shaping based on port, that is, all traffic on the port is
shaped. It also supports traffic shaping for a specific queue. You can choose to
achieve one of them by selecting different parameters in the command.
See the corresponding Command Manual for details of the commands.
This configuration re-labels priority value for the packets that match the ACL in
these ways: using the service parameters allocated by the switch, re-allocating
service parameters by searching the mapping table based on the packet DSCP
value, re-allocating service parameters by searching the mapping table based on
the specified DSCP value and EXP value, customizing service parameters for the
packets.
For interface cards, perform the following configurations in Ethernet port view.
Command
traffic-shape [ queue queue-id ] max-rate burst-size
undo traffic-shape [ queue queue-id ]
QoS Configuration 193