Hierarchical CoS

This section details Hierarchical CoS. Before the deep dive, let’s get some terminology and basic concepts out of the way via Table 5-9 and its terminology definitions.

Table 5-9. H-CoS and MX Scheduling Terminology.




Committed information rate, also known as “guaranteed rate.” This parameters specifies the minimum bandwidth for an IFL-Set or VLAN/IFL.


A Customer VLAN, the inner tag on a dual tagged frame, often used interchangeably with IFL as each customer VLAN is associated with a unique IFL. See also S-VLAN.


Keyword in a class of service scheduler container. Specifies the priority of excess bandwidth. Excess bandwidth is the bandwidth available after all guaranteed-rates have been satisfied. Options are Excess High or Low (EH/EL).


Keyword in class of service traffic control profile and scheduler containers. Specifies how excess bandwidth is distributed amongst peers in a scheduler-hierarchy.

Guaranteed-rate (G-Rate)

See “CIR.” In the Trio Queuing Model, the guaranteed rate is denoted as “G” for guaranteed. G-Rate priority is Strict-High/High, Medium, or Low (SH, H, M, L). Queues transmit rate is considered a G-Rate when not overbooked, else the committed information rate in Traffic Control Profiles (TCPs).

Interface Set (IFL-Set)

A logical grouping of C-VLANs/IFLs or S-VLANs. Allows aggregate-level shaping and scheduling over a set of IFLs or S-VLANs.


A scheduler node is the entity that manages dequeueing traffic from ...

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