"The Covergence Session Manager’s high-performance design and flexible distributed architecture allows us to scale performance and capacity without increasing management complexity.”
Bob Decker, Senior Vice President, New Global Telecom

Registration Scaling
Registration scaling is one of the most common pain points on the access edge. The CSM was purpose-built to address the requirements of the access edge.

User agents such as phones and terminal adapters register periodically with their home servers and this traffic imposes a processing burden on the access edge session border (SBC) controller. Poor registration processing capability forces many organizations to have to purchase additional SBC capacity, artifically driving up the costs and management complexity. As a result many of our customers first come to us because problems managing registrations and re-registrations.

Problem #1 Degraded Performance:
Most SIP servers require user agents to register at a low rate (e.g. once per hour) to maintain registration state. However, when a user agent running SIP over a connectionless transport protocol (i.e. UDP) is located on the “far side” of a network address translation (NAT) function, the user agent registration rates are much more frequent (e.g. every 30, 45 or 60 seconds) in order to maintain the address and port bindings in the far-end NAT. This significantly increases the registration load on the access edge SBC. To estimate the registration load you need to know the total number of registered users, the normal registration rate, the number of SIP/UDP user agents located behind far-end NATs and the accelerated (NAT traversal) registration rate. By way of example an environment with 1M SIP/UDP user agents, all located behind far-end NATs, with registration rates set to 30 seconds would generate over 33,000 registrations per second.

Problem #2 Service Outages:


A registration flood is tidal wave of registrations that occur simultaneously as a result of a network outage, a power fluctuation or a mis-configured or bug ridden device. An “all in” registration flood (from a power outage) for the 1M SIP/UDP user agents example above could create a registration flood of 100,000 – 500,000 registrations a second. Even a few bug-ridden devices can generate tens-of-thousands to hundreds-of-thousands of registrations per second and bring performance and quality below acceptably levels.

The Covergence Solution
The Covergence Session Manager (CSM) family of high-capacity access solutions are designed to scale the access edge. A single CSM mid-range and high-end system can support hundreds of thousands of concurrent connectionless (UDP) or connection-oriented (TCP, TLS) sessions with high re-registration rates.

The CSM's high capacity registration processing handles up to 9,000 re-registrations per sec per chassis (equivalent to 270,000 users at 30 seconds per re-reg per user). In addition the CSM Stateful Registration Architecture smooths out positive and negative registration spikes and maintains connectivity through wide variations in registration traffic load.

The CSM's ability to scale registrations is unique in the industry.