EtoPE QoS for Frame Relay Access CE Outbound

Managed CE Outbound

WRED

Mark

FRTS

FRF.12

cRTP

RCL Head Office Campus

RCL Head Office Campus class-map match-all PREMIUM

match ip access-group 101 class-map match-all BUSINESS match ip acces s-group 102

policy-map OUT-POLICY class PREMIUM priority percent 25 set ip dscp ef class BUISNESS bandwidth remaining percent 75 set ip dscp af31 random-detect dscp-based class class-default bandwidth remaining percent 25 set ip dscp 0 random-detect dscp-based

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

Both the enterprise voice bearer and voice control traffic will be matched using access-list 101 and will be serviced by the LLQ with a maximum bandwidth guarantee of 25 percent of the link bandwidth.

The enterprise mission-critical traffic will be matched using access-list 102 and has a minimum guaranteed bandwidth of 75 percent of the remaining available bandwidth after the LLQ has been serviced.

All other traffic from the enterprise will be classified into the default class and has a minimum guaranteed bandwidth of 25 percent of the remaining available bandwidth after the LLQ has been serviced.

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

In the example, the CE and PE link is a Frame Relay link and traffic shaping is implemented on the PVC using Frame Relay traffic shaping (FRTS).

FRTS is configured using a Frame Relay map class with a CIR of 256 kbps, a Bc of 2560 bits, a Be of 0 (no bursting), and a minCIR of 256 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 of the VC. The Bc is the amount you will send per time interval. The CIR and Bc will be used to compute a committed time window (Tc), where Tc = Bc / CIR. For FRTS, CLI will only allow Bc values that would result in a Tc that is between 10 ms and 125 ms. A recommended value for Tc is 10 ms. To get a Tc of 10 ms, the Bc should be set to 1/100 of the CIR. The minCIR parameter is required, because Cisco IOS will only allow 75 percent of the minCIR to be reserved by the QoS policy applied to the FRTS map class. If the minCIR is not configured, it will default to 50 percent of the CIR, which is not desired.

FRF. 12 fragmentation 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 Frame Relay PVC is carrying VoIP traffic, the recommendation is to set the minCIR =

CIR and not use adaptive traffic shaping, because by the time the backward explicit congestion notification (BECN) is received by the sender, drops are already happening on the Frame Relay switch.

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