Nokia 7705 - 3.1.8 Per-VLAN Network Egress Shapers

Quality of Service Guide QoS and QoS Policies
Edition: 01 3HE 11014 AAAC TQZZA 41
The second-tier shaper—that is, the per-SAP aggregate shaper—is used to limit the
traffic at a configured rate on a per-SAP basis. The per-queue rates and behavior are
not affected when the aggregate shaper is enabled. That is, as long as the aggregate
rate is not reached then there are no changes to the behavior. If the aggregate rate
limit is reached, then the per-SAP aggregate shaper throttles the traffic at the
configured aggregate rate while preserving the 16-priority scheduling priorities that
are used on shaped SAPs.
3.1.8 Per-VLAN Network Egress Shapers
This section provides information on per-VLAN network egress shapers for Gen-1
and Gen-2 adapter cards and platforms. For information on Gen-3 adapter cards and
platforms, see QoS for Gen-3 Adapter Cards and Platforms.
The 7705 SAR supports a set of eight network egress queues on a per-port or on a
per-VLAN basis for network Ethernet ports. Eight unique per-VLAN CoS queues are
created for each VLAN when a per-VLAN shaper is enabled. When using per-VLAN
shaper mode, in addition to the per-VLAN eight CoS queues, there is a single set of
eight queues for hosting traffic from all unshaped VLANs, if any. VLAN shapers are
enabled on a per-interface basis (that is, per VLAN) when a network queue policy is
assigned to the interface. See Per-VLAN Shaper Support for a list of cards and
nodes that support per-VLAN shapers.
On a network port with dot1q encapsulation, shaped and unshaped VLANs can
coexist. In such a scenario, each shaped VLAN has its own set of eight CoS queues
and is shaped with its own configured dual-rate shaper. The remaining VLANs (that
is, the unshaped VLANs) are serviced using the unshaped-if-cir rate, which is
configured using the config>port>ethernet>network>egress>unshaped-if-cir
command. Assigning a rate to the unshaped VLANs is required for arbitration
between the shaped VLANs and the bulk (aggregate) of unshaped VLANs, where
each shaped VLAN has its own shaping rate while the aggregate of the unshaped
VLANs has a single rate assigned to it.
Per-VLAN shapers are supported on dot1q-encapsulated ports. They are not
supported on null- or qinq-encapsulated ports.
Figure 5 illustrates the queuing and scheduling blocks for network egress VLAN
traffic.
Note: Due to space limitations in Figure 5, the second-tier, per-VLAN aggregate shapers
are represented as a single loop containing the label “per VLAN”, even though they are
dual-rate shapers similar to the third-tier network aggregate shaper.