Queues can be created for each forwarding class to determine the manner in which the queue output is scheduled and the type of parameters the queue accepts. The 7705 SAR supports eight forwarding classes per SAP. Table: Default Forwarding Classes shows the default mapping of these forwarding classes in order of priority, with Network Control having the highest priority.
FC Name |
FC Designation |
Queue Type |
Typical use |
|---|---|---|---|
Network Control |
NC |
Expedited |
For network control and traffic synchronization |
High-1 |
H1 |
For delay/jitter sensitive traffic |
|
Expedited |
EF |
For delay/jitter sensitive traffic |
|
High-2 |
H2 |
For delay/jitter sensitive traffic |
|
Low-1 |
L1 |
Best Effort |
For best-effort traffic |
Assured |
AF |
For best-effort traffic |
|
Low-2 |
L2 |
For best-effort traffic |
|
Best Effort |
BE |
For best-effort traffic |
The traffic flows of different forwarding classes are mapped to the queues. This mapping is user-configurable. Each queue has a unique priority. Packets from high-priority queues are scheduled separately, before packets from low-priority queues. More than one forwarding class can be mapped to a single queue. In such a case, the queue type defaults to the priority of the lowest forwarding class (see Queue Type for more information on queue type). By default, the following logical order is followed:
FC-8 - NC
FC-7 - H1
FC-6 - EF
FC-5 - H2
FC-4 - L1
FC-3 - AF
FC-2 - L2
FC-1 - BE
At access ingress, traffic can be classified as unicast traffic or one of the multipoint traffic types (broadcast, multicast, or unknown (BMU)). After classification, traffic can be assigned to a queue that is configured to support one of the four traffic types, namely:
unicast (or implicit)
broadcast
multicast
unknown