Digisol DG-GS4826S, Management Manual

Page: 241 / 1344

– 241 –
11
C
LASS OF
S
ERVICE
Class of Service (CoS) allows you to specify which data packets have
greater precedence when traffic is buffered in the switch due to congestion.
This switch supports CoS with eight priority queues for each port. Data
packets in a port’s high-priority queue will be transmitted before those in
the lower-priority queues. You can set the default priority for each
interface, and configure the mapping of frame priority tags to the switch’s
priority queues.
This chapter describes the following basic topics:
u
Layer 2 Queue Settings – Configures each queue, including the default
priority, queue mode, and queue weight, and mapping of packets to
queues based on CoS tags.
u
Layer 3/4 Priority Settings – Maps TCP ports, IP precedence tags, or IP
DSCP tags to class of service values.
L
AYER
2 Q
UEUE
S
ETTINGS
This section describes how to configure the default priority for untagged
frames, set the queue mode, set the weights assigned to each queue, and
map class of service tags to queues.
S
ETTING THE
D
EFAULT
P
RIORITY FOR
I
NTERFACES
Use the Traffic > Priority > Default Priority page to specify the default port
priority for each interface on the switch. All untagged packets entering the
switch are tagged with the specified default port priority, and then sorted
into the appropriate priority queue at the output port.
CLI R
EFERENCES
u
"switchport priority default" on page 971
C
OMMAND
U
SAGE
u
This switch provides eight priority queues for each port. It uses
Weighted Round Robin to prevent head-of-queue blockage, but can be
configured to process each queue in strict order, or use a combination
of strict and weighted queueing.
u
The default priority applies for an untagged frame received on a port
set to accept all frame types (i.e, receives both untagged and tagged
frames). This priority does not apply to IEEE 802.1Q VLAN tagged
frames. If the incoming frame is an IEEE 802.1Q VLAN tagged frame,
the IEEE 802.1p User Priority bits will be used.