PEtoCE QoS for Frame Relay Access PE Outbound

class-map match-all PREMIUM match ip dscp ef class-map match-all BUSINESS match ip dscp af31 af32 af33

policy-map OUT-POLICY class PREMIUM

priority percent 25 class BUSINESS

bandwidth percent remaining 75 random-detect dscp-based class class-default bandwidth percent remaining 25 bandwidth percent remaining 25 random-detect dscp-based

The figure shows the QoS configurations on the egress PE router outbound interface to implement the required QoS policy required for each of the three service provider traffic classes.

In this case, a traffic policy called "OUT-POLICY" is configured to provide the LLQ or CBWFQ, and WRED. Each traffic class bandwidth guarantee is configured using a percentage rather than a fixed bandwidth in kbps.

No inbound policy is required on the CE router.

PE-to-CE QoS for Frame Relay Access PE Outbound (Cont.)

Systems, Inc. All rights reserved

In this example, the PE-CE link is a Frame Relay link and FRTS is enabled on the PVC.

FRTS is configured using a Frame Relay map class with a CIR of 512 kbps, a Bc of 5120 bits, a Be of 0 (no bursting), and a minCIR of 512 kbps. The CIR is the rate at which you want to normally send when there is no congestion. The CIR needs to be the remote end-link speed or the actual CIR on a virtual circuit. The Bc is the amount you will send per time interval. The CIR and Bc will be used to compute a Tc, where Tc = Bc / CIR. For FRTS, CLI will only allow Bc values that would result in a 125 ms > Tc >10 ms. A recommended value for Tc is 10 ms. To get a Tc of 10 ms, the Bc should set to 1/100 of the CIR.

FRF. 12 fragmentation and interleaving and cRTP are also enabled within the Frame Relay map class. The fragment size in bytes is set to derive a maximum delay of 10 ms to 15 ms. The fragment size should be the same on both ends.

The "OUT-POLICY" traffic policy is applied within the Frame Relay map class.

Note If the FR PVC is carrying VoIP traffic, the recommendation is to set the minCIR = CIR and not use adaptive traffic shaping, because by the time the BECNs are received by the sender, drops are already happening on the Frame Relay switch.

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