If you configure CoS components with LFI on a Services Router, we recommend that you follow certain recommendations for shaping rate, scheduling priority, and buffer size. For configuration instructions, see Configuring MLPPP Bundles and LFI on Serial Links. For more information about other CoS components, see the J-series Services Router Advanced WAN Access Configuration Guide.
When you configure LFI on a Services Router, we recommend that you configure the shaping rate on each constituent link of the multilink bundle. Shaping rate configuration on the constituent links is required to limit the jitter on the LFI queue. If you anticipate no delay-sensitive or jitter-sensitive traffic on the LFI queue, or if there is no LFI traffic at all, shaping rate configuration is optional.
For information about how to configure a shaping rate, see Applying Shaping Rates to Interfaces.
Services Routers support per-unit scheduling that allows you to configure scheduler maps on each MLPPP or MLFR multilink bundle. You can also configure scheduler maps on constituent links, but you must maintain the same relative priority on the constituent links and on the multilink bundle.
Table 90 shows an example of correct and incorrect relative priorities on a multilink bundle and its constituent link. In this example, you have assigned a high priority to LFI packets and a low priority to data packets on the multilink bundle. To maintain the relative priority on the constituent links, you can assign a high priority to the LFI packets and a medium-high priority to the data packets, but you cannot assign a medium-high priority to LFI packets and a high priority to data packets.
Table 90: Relative Priorities on Multilink Bundles and Constituent Links
All non-LFI traffic from the multilink bundle (from different queues) is transmitted to Q0 on the constituent links. On the constituent links, you must configure a large buffer size for Q0. If the Q0 buffer size on a constituent link is insufficient, the scheduler might drop overflowing packets.