Enterprise QoS Solution Reference Network Design Guide

ATM
WAN Edge Link-Specific QoS Design
3-32
Enterprise QoS Solution Reference Network Design Guide
Chapter 3 WAN Aggregator QoS Design
Table 3-2 Recommended Fragment Sizes, CIR, and Bc Values for Distributed Platform Frame Relay
Links (continued)
PVC Speed
Maximum Fragment
Size (for 10-ms Delay)
256 kbps 320 bytes 240,000 bps 1920 bits per Tc
512 kbps 640 bytes 480,000 bps 3840 bits per Tc
768 kbps 960 bytes 720,000 bps 5760 bits per Tc
1536 kbps — 1,440,000 bps 11520 bits per Tc
2048 kbps — 1,920,000 bps 15360 bits per Tc
Example 3-21 Distributed Platform Frame Relay QoS Design (Slow-Speed Link) Example
!
!
ip cef distributed ! 'distributed' keyword required on 7500 for ip cef
!
…
!
policy-map MQC-DTS-768
class class-default
shape average 720000 5760 0 ! Enables Distributed Traffic Shaping
service-policy WAN-EDGE ! Queues packets headed to the shaper
!
…
!
interface Serial1/1/0
no ip address
encapsulation frame-relay
no fair-queue
!
interface Serial1/1/0.12 point-to-point
description 768kbps FR DLCI to RBR-3745-Left
ip address 10.1.121.1 255.255.255.252
frame-relay interface-dlci 102
class FR-MAP-CLASS-768 ! Binds the map-class to the FR-DLCI
!
…
!
map-class frame-relay FR-MAP-CLASS-768
service-policy output MQC-DTS-768 ! Attaches nested MQC policies to map-class
frame-relay fragment 960 ! Enables FRF.12
!
Verification commands:
show policy map
show policy-map interface
Recommended
CIR Values
show frame-relay fragment (on slow-speed links only)
Recommended
Bc Values
As with Frame Relay, ATM is an NBMA medium that permits oversubscription and speed mismatches,
and thus requires shaping to guarantee service levels. In ATM, however, shaping is included as part of
the PVC definition.
Version 3.3