Traffic class to queue assignment
The assignment of the traffic classes to the egress queues is as follows:
Transparent tagging IEEE 802.1Q VLAN tagging and IEEE 802.1ad VLAN
tagging (provider bridge mode)
Traffic class Queue Traffic class Queue
3, and Internal
use
4 Internal use 3
2 3 3(and3-) 4
1 2 2 (and 2-) 2
0 1 1 (and 1-) and 0 (and 0-) 1
Notes:
1. “Internal use” means that the queue is used for network management traffic (spanning
tree BPDU’s or GVRP PDU’s, for example).
Queueing
The egress treatment is the same for customer-role and network-role ports.
Every port has four associated egress queues. The queues 1 and 2 are to be used for
delay-insensitive traffic (for instance file transfer); the queues 3 and 4 are to be used
for delay-sensitive traffic (for instance voice or video).
Please refer to “Traffic class to queue assignment” (p. 11-61) for the assignment of the
traffic classes to the egress queues.
Repeater mode
In the repeater mode, there is no queueing process as described above. All frames go
through the same queue.
Scheduler
The preceding functional blocks assure that all packets are mapped into one of the
egress queues, and that no further packets need to be dropped.
The scheduler determines the order, in which packets from the four queues are
forwarded. The scheduler on each of the four queues can be in one of two operational
modes, strict priority or weighted bandwidth. Any combination of queues in either of
the two modes is allowed. When exactly one queue is in weighted bandwidth mode, it
is interpreted as a strict priority queue with the lowest priority.
Provided that Quality of Service - Classification, Queueing and Scheduling (QoS CQS,
cf. “Quality of Service configuration options” (p. 11-52)) is enabled, the queue
scheduling method can be configured as follows:
Ethernet Overview
Classification, queueing and scheduling
....................................................................................................................................................................................................................................
365-312-801R7.2
Issue 3, May 2007
Alcatel-Lucent - Proprietary
See notice on first page
11-61
To Next Page
Loading...
