Enterprise QoS Solution Reference Network Design Guide

Chapter 3 WAN Aggregator QoS Design
Version 3.3
WAN Edge Link-Specific QoS Design
The new setting can be verified quickly with the same show atm pvc command variation, as shown in
Example 3-25 (see Example 3-26).
Example 3-26 show atm pvc Verification of Tx-ring Setting After Tuning
WAG-7206-Left#show atm pvc 0/12 | include TxRingLimit
VC TxRingLimit: 3 particles
Slow-Speed (£ 768 kbps) ATM Links: ATM PVC Bundles
Recommendation: Queuing policies for voice are not required (because voice uses a dedicated ATM
PVC). Tune the ATM PVC Tx-ring to 3.
An alternative option to provisioning QoS on slow-speed ATM PVCs is to use PVC bundles, as
illustrated in Figure 3-15. PVC bundles consist of two (or more) PVCs with different ATM traffic
contracts, grouped together in a logical association in which IPP levels determine the PVC to which the
packet will be directed. The decision to use PVC bundles instead of MLPoATM for slow-speed ATM
links is usually a matter of economics (because service providers often offer attractive pricing for PVC
bundles) and configuration/management complexity comfort levels.
Figure 3-15 Slow-Speed ATM PVC Bundles
WAN Aggregator
ATM PVC for Voice
ATM PVC for Data
ATM
Cloud
Branch Router
In Example 3-27, one PVC (for voice) has a variable bit rate, non-real-time (VBR-nrt) ATM traffic
contract and an admission criterion of IPP 5, while another PVC (for data) has an unspecified bit rate
(UBR) ATM traffic contract and accepts all other precedence levels.
Again, it is also recommended that the TX-ring be tuned to 3 on such slow-speed ATM PVCs.
Example 3-27 Slow-Speed (ð 768 kbps) ATM PVC Bundles QoS Design Example
!
class-map match-any Call Signaling
match ip dscp cs3
match ip dscp af31
class-map match-any Critical Data
match ip dscp cs6
match ip dscp af21
match ip dscp cs2
!
!
policy-map WAN-EDGE-DATA-PVC ! Only data queuing is required (no voice)
class Call Signaling
bandwidth percent 5
class Critical Data
bandwidth percent 40
class class-default
fair-queue
!
vc-class atm VOICE-PVC-256 ! Voice PVC-class definition
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