Telecom network operators, cable companies, and ISPs are now realizing what voice-over-IP (VOIP) vendors have known for some time: Any VOIP deployment will require session border control functionality in one form or another.
A session border controller (SBC) is a piece of network equipment or a collection of functions that control real-time session traffic at the signaling, call-control, and packet layers as they cross a notional packet-to-packet network border between networks or between network segments. SBCs are critical to the deployment of VOIP networks, because they address the inability of real-time session traffic to cross network address translation (NAT) device or firewall boundaries. Signaling protocols such as H.323, MGCP, and Session Initiation Protocol (SIP) transfer information including media session endpoint IP addresses and UDP port numbers in different layers above OSI Layer 4 (IETF TCP/UDP). This information cannot be seen by a normal firewall or NAT device, so the subsequent sessions set up are not recognized, do not pass through firewalls, and have incompatible IP addresses across NAT boundaries. SBCs allow NAT and firewall traversal, normally by incorporating those elements with signaling controllers for the required signaling protocols.
VOIP Session Border Controllers: A Heavy Reading Competitive Analysis presents the most detailed, comprehensive competitive analysis of session border controllers ever undertaken. In key product categories, it provides granular information on every important aspect of the functionality and performance of each vendor's offering, in matrix format. It then uses a weighted system to provide a high-level view of which SBCs represent the best overall choice for different applications.
This report is based on extensive one-on-one interviews with service providers and equipment vendors, as well as an exclusive online survey of telecom operators worldwide. Sixty-six respondents, representing more than five dozen network operators, participated in the survey. Their responses offer insights into current network utilization levels, convergence plans, carrier interest in "packet-aware" metro and access networks, and finally, carrier awareness of pseudowires and the values associated with their use.
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