Toll-Quality for Each Call
There are three primary issues that impact VoIP quality: delay, jitter and packet loss. If there is too much delay, the conversation sounds like a two-way radio conversation where one party has to wait for the other to finish before they can speak. Variations in delay, or jitter, will cause choppy communications. Packet loss, generally caused by network congestion, will result in unintelligible speech. Achieving well-established “toll-quality” metrics requires a traffic management solution that enforces multiple bandwidth management policies on a per call basis. The Converged Access QoSWorks traffic management solution meets this objective with the ability to specifically manage precise latency, jitter and packet loss attributes. The solution is based on patent-pending technology that first allows IT managers to dynamically discover and guarantee performance for a full range of VoIP protocols (e.g., H.323, SIP, MGCP, Cisco's Skinny) and codecs ( such as G.711, G.726, G.729). Explicit bandwidth, latency and jitter requirements are then established and enforced for each individual. Strict admission control policies further protect the quality of calls that are in process. At the same time, QoSWorks assures that other applications using the network are fully protected.Per Call Performance Guarantees
The QoSWorks traffic management system classifies voice separately from data traffic. Each voice call has its own session bandwidth and priority. High priority data applications separately receive guaranteed bandwidth to ensure that the introduction of voice traffic does not degrade business application performance. To achieve toll quality voice, traffic must be controlled in both the inbound and outbound directions. Multiple bandwidth management techniques are then combined. Techniques like CBQ set priority with precise bandwidth allocations for each call. TCP packet sizes are limited to ensure that shorter VoIP packets are not dropped or delayed behind larger packets during periods of network congestion. Jitter is managed, in part, by controlling the duration of inter-packet delays. TCP Rate controls manage the arrival of other traffic, thus reducing queuing delays. Admissions controls are also applied, as described below. The result of this tightly integrated traffic management system is precise and accurate performance for individual VoIP calls.Voice Call Admission Controls
Admission control rules are implemented as new VoIP calls enter the network. Policies can include best-effort service, guaranteed minimum quality, and dropped call if the bandwidth is insufficient. This involves two techniques. "WAN-Aware" Call Provisioning : This technique brings an awareness of WAN conditions to the call provisioning process and is particularly important for managing VoIP quality. The gatekeeper or SIP proxy is signalled when set call thresholds are exceeded. This allows calls to be intelligently blocked or to proceed, ensuring that there is always adequate bandwidth to protect the quality of the call. Call Admission Control : Admission control is traditionally an admit/don't admit capability. With VoIP, admission control includes signalling intelligence to first determine the number of voice calls being initiated against current capacity of the network and then to signal the call controller whether to admit the call or not.Integration with the Existing Network
It is important to remember that other mission critical applications are operating on the converged network. These applications also require performance guarantees. QoSWorks combines the full suite of traffic management techniques to ensure that high priority applications are always protected while VoIP and other applications are added to the network.Other Products in this category:
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