Link Services IQ CoS Components

For link services IQ (lsq) interfaces, you can specify a scheduler map for each logical unit. A logical unit represents either an MLPPP bundle or a DLCI configured on a FRF.16 bundle. The scheduler is applied to the traffic sent to an AS or MultiServices PIC running the Layer 2 link service package.

If you configure a scheduler map on a bundle, you must include the per-unit-scheduler statement at the [edit interfaces lsq-fpc/pic/port] hierarchy level. If you configure a scheduler map on an FRF.16 DLCI, you must include the per-unit-scheduler statement at the [edit interfaces lsq-fpc/pic/port:channel] hierarchy level. For more information, see the JUNOS Class of Service Configuration Guide.

If you need latency guarantees for multiclass or LFI traffic, you must use channelized IQ PICs for the constituent links. With non-IQ PICs, because queueing is not done at the channelized interface level on the constituent links, latency-sensitive traffic might not receive the type of service that it should. Constituent links from the following PICs support latency guarantees:

• Channelized E1 IQ PIC
• Channelized OC3 IQ PIC
• Channelized OC12 IQ PIC
• Channelized STM1 IQ PIC
• Channelized T3 IQ PIC

For scheduling queues on a logical interface, you can configure the following scheduler map properties at the [edit class-of-service schedulers] hierarchy level:

• buffer-size—The queue size; for more information, see Scheduler Buffer Size.
• priority—The transmit priority (low, high, strict-high); for more information, see Scheduler Priority.
• shaping-rate—The subscribed transmit rate; for more information, see Scheduler Shaping Rate.
• drop-profile-map—The random early detection (RED) drop profile; for more information, see Drop Profiles.

When you configure MLPPP and FRF.12 on M-series and T-series routing platforms, you should configure a single scheduler with non-zero percent transmission rates and buffer sizes for queues 0 through 3, and assign this scheduler to the link services IQ interface (lsq) and to each constituent link.

When you configure FRF.16 on M-series and T-series routing platforms, you can assign a single scheduler map to the link services IQ interface (lsq) and to each link services IQ DLCI, or you can assign different scheduler maps to the various DLCIs of the bundle, as shown in Examples: Configuring an NxT1 Bundle Using FRF.16. For the constituent links of an FRF.16 bundle, you do not need to configure a custom scheduler. Because LFI and multiclass are not supported for FRF.16, the traffic from each constituent link is transmitted from queue 0. This means you should allow most of the bandwidth to be used by queue 0. The default scheduler transmission rate and buffer size percentages for queues 0 through 3 are 95, 0, 0, and 5 percent, respectively. This default scheduler sends all user traffic to queue 0 and all network-control traffic to queue 3, and therefore it is well suited to the behavior of FRF.16. You can configure a custom scheduler that explicitly replicates the 95, 0, 0, and 5 percent queuing behaviors, and apply it to the constituent links.

Note: On T-series and M320 platforms, the default scheduler transmission rate and buffer size percentages for queues 0 through 7 are 95, 0, 0, 5, 0, 0, 0, and 0 percent.

For link services IQ interfaces (lsq), these scheduling properties work as they do in other PICs, except as noted in the following sections.

Note: On T-series and M320 platforms, lsq interfaces do not support DiffServ code point (DSCP) and DSCP-IPv6 rewrite markers.