Q
Problem solve Get help with specific problems with your technologies, process and projects.

When does latency become an issue to the flow of voice traffic?

We are decommissioning Newbridge MUXs and tie lines and redirecting voice traffic from existing PBXs to a Cisco VG200 and across leased lines (T1 or E1) that incorporate existing Expand compressors and Cylink encryptors on both ends of circuits. The edge routers use LLQ for QoS. My concern is when does latency become an issue to the flow of voice traffic as these packets traverse the WAN.

We are decommissioning Newbridge MUXs and tie lines and redirecting voice traffic from existing PBXs to a Cisco VG200 and across leased lines (T1 or E1) that incorporate existing Expand compressors and Cylink encryptors on both ends of circuits. The edge routers use LLQ for QoS. My concern is when does latency become an issue to the flow of voice traffic as these packets traverse the WAN.

I believe the amount and ratio of data to voice traffic will determine when latency starts to become an issue. Currently, there is an average 250ms response time (ping test) between the States and a remote branch in Argentina. The compressors have caching mechanisms to assist with traffic flow and may employ QoS mechanisms. Is this a recommended design? What are our alternatives?

Your thoughts are appreciated.
Rick
 

The amount of data and voice traversing your private lines (for WAN connectivity) will definitely affect the quality of the voice. The primary performance metric you should be looking at is jitter. Even if the latency may be high (not unreasonably high though), if the jitter is good the quality of the voice will be good. An alternative you may want to consider is running some or all of the traffic over an IP VPN. Most public IP networks have immense capacity so you're likely to have no problems delivering great quality for applications over them. You may have to prioritize traffic on the last mile circuit if the utilization is high.

For more information, view this tip to learn how to optimize voice over WAN.

 

This was last published in September 2002

Dig Deeper on Network Infrastructure

Have a question for an expert?

Please add a title for your question

Get answers from a TechTarget expert on whatever's puzzling you.

You will be able to add details on the next page.

Start the conversation

Send me notifications when other members comment.

Please create a username to comment.

-ADS BY GOOGLE

SearchUnifiedCommunications

SearchMobileComputing

SearchDataCenter

SearchITChannel

Close