3Com 4007, Руководство по внедрению, Страница: 205 / 684

CoS in Your System 205
For example, if you enter any whole number between 88 and 99 as the
rate limit, the working rate limit will be 87.5; that is, for every 8 packets
received on a given port, 7 packets are selected from queue 1 and 1
packet is selected from queue 2.
Table 44 provides a reference chart:
Important Considerations
■
If the number of packets in queue 1 exceeds the rate limit, packets are
held in the queue 1 buffer. When this buffer becomes full, the module
begins to drop packets from that queue.
■
The default rate limit of 100 percent means that queue 1 can “starve”
queue 2 under the right conditions. That is, on a given port, packets in
queue 2 are always buffered if there are any packets in queue 1 on
that same port. Queue 2 packets are processed only after all packets
from queue 1 have been processed. If the queue 2 buffers become
full, the module begins to drop packets in that queue.
Table 44 Implementation Guidelines for the CoS Rate Limit
Operating
percentage Range of values that
you could enter
For every 8 packets received on
the port and processed, the
number of packets that are
selected from queue 1
12.5 1–24 1
25 25–37 2
37.5 38–49 3
50 50–62 4
62.5 63–74 5
75 75–87 6
87.5 88–99 7
100 100 8