To represent a downstream network aggregation node in the local node scheduling hierarchy, a new scheduling node, referred to as virtual port (Vport in CLI) have been introduced. The Vport operates exactly like a port scheduler except multiple Vport objects can be configured on the egress context of an Ethernet port.
This feature applies to the 7450 ESS and 7750 SR only.
Figure: Applying a port scheduler policy to a Vport shows the use of the Vport on an Ethernet port of a Broadband Network Gateway (BNG). In this case, the Vport represents a specific downstream DSLAM.
The user adds a Vport to an Ethernet port using the following command:
config>port>ethernet>access>egress>vport vport-name create
The Vport is always configured at the port level even when a port is a member of a LAG. The Vport name is local to the port it is applied to but must be the same for all member ports of a LAG. However, it does not need to be unique globally on a chassis.
The user applies a port scheduler policy to a Vport using the following command:
config>port>ethernet>access>egress>vport>port-scheduler-policy port-scheduler-policy-name
A Vport cannot be parented to the port scheduler when the Vport is using a port scheduler policy. It is important that the user ensures that the sum of the max-rate parameter value in the port scheduler policies of all Vport instances on a specific egress Ethernet port does not oversubscribe the port’s rate. If it does, the scheduling behavior degenerates to that of the H/W scheduler on that port. A Vport that uses an agg-rate, or a scheduler-policy, can be parented to a port scheduler. This is described in Applying aggregate rate limit to a Vport. The application of the agg-rate rate, port-scheduler-policy, and scheduler-policy commands under a Vport are mutually exclusive.
Each subscriber host policer or queue is port parented to the Vport that corresponds to the destination DSLAM using the existing port-parent command:
config>qos>sap-egress>queue>port-parent [weight weight]
[level level] [cir-weight cir-weight] [cir-level cir-
level]config>qos>sap-egress>policer>port-parent [weight
weight] [level level] [cir-weight cir-weight] [cir-
level cir-level]This command can parent the policer or queue to either a port or to a Vport. These operations are mutually exclusive in CLI. When parenting to a Vport, the parent Vport for a subscriber host policer or queue is not explicitly indicated in the command; it is determined indirectly. The determination of the parent Vport for a specific subscriber host queue is described in the 7450 ESS, 7750 SR, and VSR Triple Play Service Delivery Architecture Guide.
Subscriber host policers or queues, SLA profile schedulers, subscriber profile schedulers, and PW SAPs (in IES or VPRN services) can be parented to a Vport.