Configuring Fr Qos; Fr Qos Parameters; Frts; Functionality - HP FlexNetwork MSR Series Configuration Manuals

Configuring FR QoS

On an FR interface, you can use generic QoS services to perform traffic shaping, traffic policing,
congestion management, and congestion avoidance. You can also use FR-specific QoS
mechanisms, including FR traffic shaping (FRTS), FR traffic policing (FRTP), FR congestion
management, FR discard eligibility (DE) rule list, and FR queuing management.
FR QoS works on a per-PVC basis and is more flexible than generic QoS. For more information
about Frame Relay, see Layer 2—WAN Configuration Guide.
Figure 35 FR QoS implementation
Traffic shaping
DTE
Router A
DE rule

FR QoS parameters

FR QoS uses the following parameters:
•
CIR ALLOW—Average transmission rate guaranteed on a PVC when no congestion occurs.
•
CIR—Minimum transmission rate guaranteed on a PVC even if congestion occurs in the
network.
•
CBS—Size of traffic that a PVC is committed to transmitting within the interval of Tc when
congestion occurs in the network.
•
EBS—Maximum size of traffic that can exceed CBS on a PVC within the interval of Tc. When
congestion occurs in the network, the traffic of the EBS size is dropped first. Transmitting traffic
of the EBS size is not guaranteed by the FR network.

FRTS

Functionality

FRTS limits the outgoing traffic rate and smoothes bursts for PVCs. Then, PVCs can transmit traffic
at a constant rate. FRTS applies to the outgoing interface of a switch. You can use FRTS to remove
the bottleneck created when the input rate of a device is slower than the output rate of the sending
device.
As shown in
•
Router B transmits packets to Router A at 128 kbps.
•
The maximum interface rate of Router A is only 64 kbps.
The disparity in traffic rate creates a bottleneck on the interface that connects Router A to the FR
network.
To avoid packet loss, you can configure FRTS with the CIR ALLOW 64 kbps and the CIR 32 kbps on
the outgoing interface Serial 2/1/1 of Router B. Then, the interface can transmit packets constantly at
Data flow direction
Traffic policing
NNI
DCE
Router B
Congestion
management
Figure 36:
Frame relay
network
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