Enhanced Subscriber Management Subscriber Logical Interfaces or Interface Sets Over Underlying Logical Interfaces for a CoS scheduler Hierarchy

In certain Broadband Remote Access Server (B-RAS) deployments, when you use an interface set to denote a home network, it might be necessary to configure the home network and the access node (such as a digital subscriber line access multiplexer, or DSLAM) in a scheduler hierarchy. This method of hierarchical scheduler is necessary in agent circuit identifier (ACI) VLANs because a home or an ACI is always an interface set in such topologies. You can now enable an enhanced subscriber management logical interface, such as an MPLS pseudowire logical interface to function as a Layer 2 node in a CoS hierarchical scheduler. A subscriber logical interface is considered to operate at Layer 2 only if you configure three-level hierarchical scheduling on the logical tunnel anchor point on the physical interface (the IFD). An MPLS pseudowire is a virtual device that is stacked above the logical tunnel anchor point. Implicit hierarchy processes the interface stack properly in such a setup. To configure three-level hierarchical scheduling, include the implicit- hierarchy option at the [edit interfaces “$junos-interface-ifd-name” hierarchical-scheduler] or the [edit interfaces lt-device hierarchical-scheduler] hierarchy level. If the implicit-hierarchy option is not set on the logical tunnel anchor point, logical interfaces behave normally with the hierarchical-scheduler mode configured with or without the hierarchical-scheduler maximum-hierarchy-levels option under the [edit interfaces interface-name hierarchical-scheduler] statement.

In this case, when you apply a traffic-control profile to the pseudowire and service logical interfaces, they both reside in level 3 scheduler nodes and do not form a scheduling hierarchy, which might not be the desirable behavior. Subscriber logical interfaces at Layer 3 that are stacked over the underlying logical interfaces at Layer 2 are supported if the Layer 2 logical interface is an underlying interface of the Layer 3 interface.

For example, if a PPPoE logical interface contains an underlying logical interface, ge-1/0/0.100, the ge-1/0/0.100 interface can be at Layer 2 and the PPPoE logical interface can be at Layer 3. You can also configure PPP or IP demux interfaces in such a fashion at Layer 3. Similarly, you can configure logical interfaces at Layer 2 that serve as underlying interfaces for logical interface sets, such as PPPoE ACI interface sets or IP demux interface sets, where all the member logical interfaces of the interface set contain the same underlying logical interface at Layer 2. You can configure the logical interfaces at Layer 2 in a dynamic profile or in a static CoS configuration.

Dynamic profile CoS configuration for underlying logical interfaces is supported because two interface stanzas with TCPs in one dynamic profile are considered valid. For dynamic underlying logical interfaces, you can configure in a profile different from the client logical interface profile or in the same profile as the client profile. If the underlying logical interface is static and CoS is configured dynamically in a dynamic profile, it must be specified in the same profile as the client logical interface. However, CoS for the underlying logical interfaces must be configured either in a dynamic profile or in a static CoS because both static CoS and dynamic CoS are not supported on the same logical interface.

Reparenting is a technique that denotes the movement of the CoS hierarchical scheduler from one node to another node, such as moving all logical interfaces stacked over an underlying logical interface on top of the base physical interface to be over the underlying logical interface directly and adding the scheduling node. This movement might occur when when CoS for the underlying logical interface or the underlying interface set is configured later than the client logical interface (IP demux or PPPoE).

Reparenting is not supported for enhanced subscriber management logical interfaces in a CoS hierarchical scheduler that includes enhanced subscriber management logical interfaces over a purely dynamic column and enhanced subscriber management logical interfaces over a partially static column. The following describes real-world network environments where reparenting might be required and the alternative approaches that can be adopted in such conditions:

Adding or removing static CoS configuration from an IFL set or an underlying IFL with enhanced subscriber management logical interface on top of it—In such a scenario, adding or removing static CoS is not supported after a subscriber has logged in to the interface column in an environment where enhanced subscriber management is enabled. A commit error occurs when you attempt this CoS configuration change. This commit failure is not a problem in customer networks because the networks are previously designed, Layer 2 nodes specified, and CoS is configured much before clients are logged in.

Two dynamic profiles for Client logical interfaces over a single CVLAN (or an ACI VLAN) with underlying CoS configuration in one client profile and not in the other profile—In such a scenario, you can maintain dynamic profiles with underlying configuration to be consistent – either all profiles contain underlying CoS config or none of them contain CoS configuration. A negative acknowledgment is sent when a subscriber attempts to log in if a differing way of CoS configuration is observed in the client profiles.

A client profile for an internal node (for example, C-VLAN or IFL set) that does not contain CoS initially and CoS is applied later using a service profile—In such a scenario, it is required that you always specify CoS scheduling in the client profile if you want to reapply some of the settings using a service profile. If this method of configuration is not adopted, a negative acknowledgment is sent when a subscriber attempts to log in. Static or dynamic demux, PPPoE, or PPP interfaces over aggregated Ethernet logical interfaces are not supported.

Consider a scenario in which three subscriber queues, namely, PPPoE subscriber queue 1, PPPoE subscriber queue 2, and DHCP subscriber queues, are established. A Gigabit Ethernet interface, ge-1/0/0 is at Layer 1. Two Layer 2 interface nodes are stacked over the Layer 1 base interface. The Layer 2 interfaces are ge-1/0/0.x or demux0.x and ge-1/0/0.y or demux0.y. Logical interface sets, pppoe-iflset (for access node) and demux-iflset (for home network), are configured at Layer 3 to handle two sets of PPPoE subscriber queues respectively over the Layer 2 interface, ge-1/0/0.x or demux0.x. A traffic control profile, subscriber-tcp, is attached to both these Layer 3 IFL sets. ppp-demux-iflset (demux and pppoe) is the interface set over the Layer 2 interface of ge-1/0/0.y or demux0.y. A traffic control profile, subscriber-tcp, is attached to this interface set. ge-1/0/0.X or demux0.X is the UIFL for all logical interfaces that belong to the pppoe-iflset and demux-iflset. In this topology, ge-1/0/0.Y or demux0.Y is the UIFL for all logical interface that belong to ppp-demux-iflset.

Consider another scenario in which three susbcriber queues, PPPoE subscriber queues, demux subscriber queues, and DHCP subscriber queues, are established. A Gigabit Ethernet interface, ge-1/0/0 is at Layer 1. Two Layer 2 interface nodes are stacked over the Layer 1 base interface. The Layer 2 interfaces are ge-1/0/0.X or demux0.X, and ge-1/0/0.Y or demux0.Y. At Layer 3, pp0.XX is configured over the underlying Layer 2 interface of ge-1/0/0.X or demux0.X, demux0.ZZ is configured over the underlying Layer 2 interface of ge-1/0/0.X or demux0.X, and pp0.YY is configured over the underlying Layer 2 interface of ge-1/0/0.Y or demux0.Yge- 1/0/0.Y or demux0.Y. Traffic control profiles, subcriber-tcp, are applied to pp0.xx for PPPoE subscriber queues, to demux0.yy for demux subscriber queues, and pp0.yy for DHCP subscriber queues. In this topology, ge-1/0/0.X or demux0.X is the underlying IFL for pp0.XX and demux0.ZZ. ge-1/0/0.Y or demux0.Y is the underlying IFL for pp0.YY.