When you change the priority, you specify a number from 0 through 7. The priority number specifies the IEEE 802.1 equivalent to one of the
eight QoS queues on Ruckus devices. The numbers correspond to the queues as shown in the QoS queues table.
Although it is possible for a packet to qualify for an adjusted QoS priority based on more than one of the criteria, the system always gives a
packet the highest priority for which it qualifies. Thus, if a packet is entitled to the premium queue because of its IP source and destination
addresses, but is entitled only to the high queue because of its incoming port, the system places the packet in the premium queue on the
outgoing port.
Buffer allocation and threshold for QoS queues
By default, Ruckus FastIron software allocates a certain number of buffers to the outbound transport queue for each port based on QoS
priority. The buffers control the total number of packets permitted in the outbound queue for the port. If desired, you can increase or
decrease the maximum number of outbound transmit buffers allocated to all QoS queues, or to specific QoS queues on a port or group of
ports. For more information, refer to the
Ruckus FastIron Layer 2 Switching Configuration Guide
.
QoS marking
QoS marking
is the process of changing the packet QoS information (the 802.1p and Differentiated Services Code Point [DSCP or DiffServ]
information in a packet) for the next hop.
As an example of marking traffic coming from a device that does not support DSCP, you can change the packet IP precedence value into a
DSCP value before forwarding the packet.
You can mark a packet’s Layer 2 CoS value, its Layer 3 DSCP value, or both values. The Layer 2 CoS or DSCP value that the device marks
in the packet is the same value that results from mapping the packet QoS value into a Layer 2 CoS or DSCP value.
Marking is optional and is disabled by default. For configuration syntax, rules, and examples of QoS marking, refer to the "QoS options for
IP ACLs" section in the
Ruckus FastIron Security Configuration Guide
.
DSCP and CoS global re-marking
When marking is not used, the device performs the mappings listed for scheduling the packet, but leaves the packet QoS values
unchanged when the device forwards the packet. For more information, refer to
Quality of Service overview
on page 11. When marking is
not enabled using ACLs, a rogue host that wants preferential treatment for all its traffic can mark the DSCP field as per its requirements and
send the traffic to the device.
The internal forwarding priority can be set using an ACL only for flows that require preferential QoS treatment. For all other flows, you can
re-mark DSCP and CoS fields globally. Traffic marked by the ACL method always has a higher priority than the global marking.
When DSCP marking is configured on a given port, the DSCP field of any IPv4 packet received on the port is re-marked to the configured
value.
When CoS marking is configured, the PCP bit value in the VLAN header is re-marked to the desired value for all tagged packets. CoS
marking can be configured on a port. When configured on a port, the PCP bit in the VLAN header for all packets that egress the port is re-
marked to the configured value.
Both DSCP and CoS global marking can be configured on the ports of the modules that are configured but not physically present. When
the modules are hot-swapped, the marking is automatically applied or removed.
Quality of Service
DSCP and CoS global re-marking
Ruckus FastIron QoS and Traffic Management Configuration Guide, 08.0.70
Part Number: 53-1005294-01
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