Dave MartinVice President, Product Managementdmartin@edgewaternetworks.com

408.351.7209

Agenda

Challenges for converged networks Quality of Service Monitoring VoIP performance Troubleshooting

Solutions and best practices

Deployment examples Service Provider Enterprise

Wrap-up/summary

Quality Of Service - Why Is It Necessary?

PSTN has set the bar - VoIP as a replacement technology must offer the same quality experience

Users will tradeoff voice quality for mobility - not true for fixed line services

VoIP has very stringent jitter, latency and packet loss requirements…best effort IP forwarding is insufficient

“Becauszzzz wit_o_t it _sers w__l be unha_py!”

Ensuring A High Quality Voice Experience: Design Considerations

Prioritize voice over data traffic Take advantage of DiffServ routing if available in the network…

but remember… TOS bit setting is NOT traffic management !!

Implement traffic shaping

Provide call admission control

Route media shortest path

Pay Close Attention To Access Links

T-1/E-1Router

LAN and network core tend to be over-provisioned

Congestion Point

OC-x Multi-Gigabit

100Mbps

Managing Access Links

Traffic shapingPriority queuingDiffserv packet markingCall Admission Control

VideoData

T1 WAN Link1.544Mbits/Sec

•Video calls established•Data “shaped”

•New calls are blocked•Data not starvedcompletely

Data allowed to consume available bandwidth as calls are completed

High Priority Queue

Low Priority Queue

time

High PriorityQueue Low Priority

Queue

WAN/LAN Link

Route Media Shortest Path: Hosted PBX Scenario

Service Provider

Atlanta

San Francisco

Dallas

LegendSignaling path

Media path

Softswitch

VoIP Monitoring Issues

Distributed nature of IP networking means no natural demarcation point for problem resolution

I just had a poor quality call…...but why?

Difficult to monitor long term call performance and identify consistently poor performers

Create Demarcation Points

Location #1IP

network

Softswitchor

IP PBXIP Phone

Location #2

IP Phone

SignalingMedia

A

B CD

VoIP ManagerLocation #3

Mean Opinion Score (MOS) provides a simple listening quality scale the represents the user experience

Monitoring at points A, B, C and D provides a demarcation point between LAN and WAN

Use Call Quality Statistics To Isolate Network Problems

Common causes of jitter:

• Ethernet link set at half duplex• Ethernet link set to autonegotiate• Congestion in upstream router

Provide Proactive Support

Trend analysis at the network level can spot persistent problems

Set quality thresholds for advanced notification

Deployment Examples

• QoS • Monitoring

• QoS• Monitoring

• VPN

Best Practices Summary

Quality of Service Implement prioritization, traffic shaping, call admission

control Route calls shortest path to minimize jitter, latency, and

packet loss

Monitoring Create demarcation points Build quality monitoring into the network Use tools that report on the user experience and send

proactive notification of VoIP quality problems

Thank You!

Contact :Dave MartinVice President, Product Managementdmartin@edgewaternetworks.com408.351.7209