Session Border Control in IMS

Overview

IMS provides the new model for next generation telecommunications networks. Building on the flexibility and cost effectiveness of an IP-based infrastructure, IMS adds an all-new architecture for QoS, access control and charging to enable voice and video service delivery with guaranteed performance.

IMS enables operators to deploy the innovative services that are required to be competitive in today's market. It allows them to provide the same voice and multimedia services to all their users: mobile, fixed and nomadic, using a single converged network for the data, voice and video traffic.

This new network environment requires active management and intelligent control of access links if it is to provide the flexible, reliable platform on which operators can roll out their next generation, revenue-generating services.

One solution to these requirements is for service providers to deploy Session Border Controllers (SBCs) to protect their network border and retain control of this new network environment.

In IMS terms, a Session Border Controller implements the following signaling and control functions: P-CSCF, I-BCF, BGF and TrGW. However, its advanced capabilities go well beyond that defined by the IMS standards.

Session Border Controllers (SBCs) also allow operators to monitor and tune performance to meet agreed SLAs, tailor the service bundle to each customer with multi-level, fine-grained policy rules, facilitate services between incompatible equipment and through NATs and firewalls, and comply with legal regulations regarding privacy, reliability and lawful intercept.

For greenfield deployments, Session Border Controllers enable compatibility between the broadest set of devices. Within existing deployments, Session Border Controllers ease migration by enabling protocol-matching with legacy devices.

Metaswitch has extensive experience in supplying Session Border Control (SBC) software products to communications equipment manufacturers, enabling them to build SBC products that meet IMS requirements.

Features and Benefits

The Metaswitch Session Border Controller solution for IMS offers the following features and benefits.

• Protects from malicious and faulty devices – controlling signaling access to the enterprise network, and normalizing signaling traffic (call attempt rate limits, concurrency limits (number of calls, bandwidth requirements), ANI / DNIS).
• Controls routing of traffic to peer networks and subscribers, including prioritized location-aware handling of emergency calls.
• Maximizes usable capacity of shared-usage, bandwidth-constrained links using flexible enterprise-configured policy to apply QoS marking, bandwidth limits and prioritization to signaling and media traffic based on numerous inputs including: end-user identity, network loading, and resources requested.
• Enforces privacy of operator and customer information – strips private headers from messages leaving the core, enforces security policy on trusted and untrusted links, provides NAT for private to public address mapping, and topology hiding.
• Monitors usage and generates billing records for the media resources used by each call – the billing records are cached locally in the event of failure to contact a billing server.
• Supports wire-tapping by national intelligence agencies.
• Enables interworking with non-IMS carriers, enterprises and end-users, including H.323 / SIP interworking, DTMF and codec interworking, and NAT and firewall traversal.
• Supports multiple standard profiles e.g. IMS, SIP, H.323, including interworking between variants, extended with multi-layer policy rules and flexible customization options to support non-standard requirements.
• Provides a multi-stage policy engine to control media and signaling flows per user / user group / source / destination.
• Supports NAT, NAT traversal, codec interworking, and media policy enforcement.
• Delivers carrier-class scalability, performance and high availability – maintaining active calls over failover and in-service upgrade of signaling and media components.
• Scales to hundreds of thousands of concurrent calls and millions of BHCAs with integrated and distributed deployment models, including optimized multi-core and multi-processor support.

Solution Elements

The Metaswitch Session Border Controller solution for IMS is based on the following elements.

• DC-SBC is a fully portable source-code Session Border Controller solution for equipment vendors.
• DC-SIP is a robust, high function, flexible, portable Session Initiation Protocol (SIP) toolkit.
• DC-Diameter is a flexible, portable source code implementation of the Diameter Authorization, Authentication and Accounting (AAA) protocol.
• DC-MGCP/Megaco is a complete, scalable, and fault-tolerant source code implementation of the MGCP and Megaco/H.248 protocols.
• High Availability Framework (HAF) - Metaswitch's architecture for delivering fault tolerance and reduced downtime across the range of network protocols.
• N-BASE - Metaswitch's portable operating environment for network protocols.
• Metaswitch professional services, training, and support directly from the Metaswitch engineering organization.