Intelligent traffic-management policies can be applied to assure the performance of existing business-critical applications (e.g., CRM, SAP), while non-critical traffic is limited in the most efficient manner possible. In most cases, traffic-management policies that specifically guarantee bandwidth and response time for each application session and/or flow are required.
VolP-specific controls should be applied to assure real-time VoIP call performance (e.g., latency, jitter, bandwidth) on a call-by-call basis. This requires granular and accurate enforcement of bandwidth policies and priority control for each individual call. Given that a VoIP call is a two-way exchange, these policies should be enforced in both the inbound and outbound direction.
In addition, because a VoIP session consists of multiple flows (e.g., call setup, call control and call media) each flow should be individually protected to guarantee the integrity of the call. This means the traffic-management solution should be session aware and enforced on a per-flow basis. For example, if the call control information for a single call is compromised by the media traffic, calls may be dropped midstream.
While proactive traffic management provides a first level of control against other applications running on the network, techniques such as packet size optimization and burst control are necessary to manage the impact at a packet level. These are not available when a router alone is used to perform the traffic-management functions.
Call admission control is needed to protect VoIP calls already in progress. This should be network aware (knowledgeable about calls running on the network), with policies that establish directives on what to do when the next call is placed. In addition, the policy-management process should be kept simple, using VolP-aware defaults that apply policies dynamically based on the VoIP protocol, the codec and the number of concurrent calls to be supported.