DragonWave Horizon COMPACT - Management Traffic; Operation with 802.1 P Priority Queuing Disabled; Operation with 802.1 P Priority Queuing Enabled

DragonWave Inc. 36
Horizon Compact Release 1.01.00 Wireless Ethernet Product User Manual – Volume 2
3.3.6 Operation with 802.1P Priority Queuing Disabled
If 802.1P filtering is disabled in the Horizon Compact system, all incoming packets are treated equally and
are forwarded on a first-come first-served basis. The system operates in a FIFO (First In First Out) basis.
If the Pause Frames feature (see Section
3.4) is enabled, pause frames will be sent to the connected
switch when the input buffer is close to being full (internally set threshold). This allows time for the queue
to empty prior to more frames being received and thus avoids congestion.
3.3.7 Operation with 802.1P Priority Queuing Enabled
If 802.1P filtering is enabled in the Horizon Compact system, the scheduling mechanism can be
described as follows:
1. Select the highest priority queue which has a packet in it
2. Send that packet
If COS CIRs are set for the queues, then the scheduling mechanism can be described as follows:
1. Select the highest priority queue which has a packet in it, and hasn’t used up its CIR budget
2. Send that packet
The operation of the Scheduler is affected by both the user-configurable CIR and CoS Queue CBS
settings.
If the Pause Frames feature (see Section
3.4) is enabled, pause frames will be sent to the connected
switch when the input buffer is close to being full (internally set threshold).
The Horizon Compact system also allows any packets without a VLAN tag to be allocated an 802.1P CoS
level (“set untagged packet priority”). If the “set untagged packet priority” is not configured, then all
untagged packets will be forwarded through Queue 1.
Horizon Compact is also able to manage Q-in-Q or Super VLAN traffic. The system can be configured to
use either an encapsulated frame’s priority tag or the encapsulating frame’s priority tag, in determining
priority handling.
3.3.8 Management Traffic
Slow Ethernet services and multicast packets are handled by a special Queue inside the Horizon
Compact. The Queue is not user-accessible. It works similar to an Expedite Queue in that it ensures
management traffic is passed through in an “expedited” fashion. It does not affect, nor is related to the
four Queues within Horizon Compact.
Packets destined for the 01-80-C2-00-00-xx MAC addresses are sent to the internal Queue. Examples:
STP, RSTP, MSTP LACP, Pause Frames, GARP (GMRP,GVRP), bridge broadcasts, OAM, LLDP, Port
based authentication are all sent to the internal Queue and are transmitted in an expedited fashion.
Other packets that the user determines must be treated in an expedited fashion, such as “keep-alive”
packets and MRP packets, must be assigned a CoS within the switch, then assigned to the appropriate
Queue within Horizon Compact.