Scheduling and Shaping in Hierarchical CoS Queues for Traffic Routed to GRE Tunnels

Understanding Scheduling and Shaping of Traffic Routed to GRE Tunnels

On MX Series routers running Junos OS Release 12.3R4 or later revisions, 13.2R2 or later revision, or 13.3R1 or later, you can manage CoS scheduling and shaping of traffic routed to generic route encapsulation (GRE) tunnel interfaces configured on MPC1 Q, MPC2 Q, or MPC2 EQ modules.

A single egress logical interface can be converted to multiple GRE tunnel interfaces. A GRE tunnel physical interface can support many logical interfaces, but one or more of those logical interfaces might not have an output traffic control profiles attached. If a GRE tunnel logical interface is not attached to an output traffic control profile, the router does not assign the interface a dedicated scheduler. Instead, the interface uses a reserved scheduler intended for all unshaped tunnel traffic (traffic entering a GRE tunnel logical interface that does not have an explicit traffic control profile configuration).

Configuration Overview

At GRE tunnel interfaces, the output-traffic-control-profile configuration statement can apply an output traffic scheduling and shaping profile at the physical or logical interface level, while the output-traffic-control-profile-remaining configuration statement can apply an output traffic scheduling and shaping profile for remaining traffic at the physical interface level only. Interface sets (sets of interfaces used to configure hierarchical CoS schedulers on supported Ethernet interfaces) are not supported on GRE tunnel interfaces.

By default—if you do not attach an output traffic control profile to the GRE tunnel physical interface—traffic entering the interface is scheduled and shaped using the default 95/5 scheduler with parameters as specified in the tunnel-services configuration.

If you use an output traffic control profile to configure the shaping rate at the GRE tunnel physical interface, the shaping-rate specified by the attached traffic control profile overrides the bandwidth specified as the tunnel services default value.

Configuration Caveats

When configuring hierarchical CoS scheduling and shaping of traffic routed to GRE tunnels, keep the following guidelines in mind:

• You must first configure and commit a hierarchical scheduler on the GRE tunnel physical interface, specifying a maximum of two hierarchical scheduling levels for node scaling. After you commit the hierarchical-scheduler configuration, you can configure scheduling and queuing parameters at the GRE tunnel physical or logical interfaces.

• GRE tunnel interfaces support eight egress queues only. For interfaces on MPC1 Q, MPC2 Q, and MPC2 EQ modules, you can include the max-queues-per-interface 4 statement at the [edit fpc slot-number pic pic-number] hierarchy level to configure four-queue mode for the interface. However, any GRE tunnel interfaces configured on those ports have eight queues.

• Queuing and scheduling calculations include Layer 3 fields. For GRE interfaces, Layer 3 fields include the delivery header (the outer IP header), the 4-byte GRE header, and the payload protocol header and data.