Alcatel-Lucent 7450 Quality Of Service Manual page 783

The standard ingress service queues are separated into two types, point-to-point and
multipoint. point-to-point queues are used either for VLL services such as Epipe or for
unicast traffic within a VPLS, VPRN or IES service. Multipoint queues are used by VPLS,
VPRN and IES services for packets that must be replicated by the switch fabric. Within the
IES and VPRN services, only IP multicast routed packets are forwarded through the
multipoint queues. Within VPLS services, broadcast (MAC DA = ff:ff:ff:ff:ff:ff), multicast
(non-broadcast destination with multicast bit set) and packets with an unknown destination
MAC address are forwarded through the multipoint queues. The standard service queues
within the SAP Ingress QoS policy are numbered 1 through 32 of which 8 may be point-to-
point queues and 24 multipoint queues. Since the HSMDA queues are not required to handle
multipoint forwarding into the switch fabric, a distinction between point-to-point and
multipoint is not present for HSMDA queues. Also, HSMDA queues are not created or
dynamically assigned to a SAP or subscriber context. Instead eight queues (numbered 1
through 8) always exist for each queue group on the XMA or MDA. Since the queue group
is assigned to the ingress SAP, all eight queues within the group automatically are available
for the SAP. This means that although a SAP ingress QoS policy does not reference a
particular queue ID, that queue is available for forwarding class mappings.
Another difference between standard service queues and HSMDA service queues is that they
cannot be associated with a port or service level virtual scheduler and so the port-parent and
parent commands are not available. Instead, each queue is implicitly mapped directly to the
HSMDA port or ingress scheduler based on the queue ID. Queue 1 is mapped to scheduling
class 1 and queue 8 is mapped to scheduling class 8. Scheduling class eight has the highest
priority and one has the lowest unless a scheduling class is grouped with another scheduling
class in which case the group itself inherits the scheduling priority of the highest class within
the group (the classes within the group are handled based on the weight assigned to each
class).
The last major difference between standard service queues and HSMDA service queues are
the support for RED slopes within the HSMDA queues. The HSMDA uses the Slope policy
the queue is associated with to configure the contour of the high and low slope within the
queue.
The SAP ingress QoS policy classification rule actions are also modified to allow for a
counter override capability. The counter override function allows for one of the eight extra
sets of counters per queue group to be used instead of the per queue counters. This is intended
for diagnostic or exception based accounting purposes.
SAP Egress QoS Policy
The SAP egress QoS policy requires the same type of modifications as the SAP ingress
policy. The policy supports queue definitions for both standard service queues and HSMDA
service queues and the forwarding class mappings to the individual queue IDs.
Quality of Service Guide
High Scale Ethernet MDA Capabilities
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