Operation Manual

192
Step
Operation
Description
1
Configure the mapping
relation between
the 802.1P
priority Tag/CoS and the TC
Required. On QoS→DiffServ→802.1P/CoS mapping
page, configure the mapping relation between the
802.1P priority Tag/CoS and the TC.
2 Select a schedule mode Required. On QoS→DiffServ→
Schedule Mode
page,, select a schedule mode.
11.1.4 Schedule Mode
On this page you can select a schedule mode for the switch. When the network is congested,
the problem that many packets compete for resources must be solved, usually in the way of
queue scheduling. The switch will control the forwarding sequence of the packets according to
the priority queues and scheduling algorithms you set. On this switch, the priority levels are
labeled as TC0, TC1…TC3.
Choose the menu QoS→DiffServ→Schedule Mode to load the following page.
Figure 11-9 Schedule Mode
The following entries are displayed on this screen:

Schedule Mode Config
SP-Mode: Strict-Priority Mode. In this mode, the queue
with higher priority
will occupy the whole bandwidth. Packets in the queue with
lower priority are sent only when the queue with higher priority is
empty.
WRR-Mode:
Weight Round Robin Mode. In this mode, packets in all the
queues are sent in order based
on the weight value for each
queue. The weight value ratio of TC0, TC1, TC2 and TC3 is
1:2:4:8.
SP+WRR-Mode: Strict-
Priority + Weight Round Robin Mode. In this mode, this
switch provides two scheduling groups, SP group and WRR
group. Queues in SP group an
d WRR group are scheduled
strictly based on strict-
priority mode while the queues inside
WRR group follow the WRR mode. In SP+WRR mode, TC3 is in
the SP group; TC0, TC1 and TC2 belong to the WRR group and
the weight value ratio of TC0, TC1 and TC2 is 1:2:4
. In this way,
when scheduling queues, the switch allows TC3 to occupy the
whole bandwidth following the SP mode and the TC0, TC1 and
TC2 in the WRR group will take up the bandwidth according to
their ratio 1:2:4.