What is Session Border Controller(SBC). And What is the Advantages of SBC. How Does It Works?

  • Unfortunately, all "education, certification, or homework" questions are explicitly off-topic here.
    – Ron Maupin
    Mar 13 '18 at 14:14

For Cisco ASR Series:

SBC Overview

SBC functions are becoming very popular in the voice-over-IP (VoIP) industry; they are the key components used for interconnecting enterprise and service provider VoIP and multimedia networks.

Because the SBC meets the growing need for secure, IP-centric interconnections between enterprise and service provider networks, a critical need for intelligent border element functions has grown. With the SBC, you can make voice or video calls without worrying about protocols, network reachability, or security of your network. Such elements provide physical and logical ingress and egress demarcations, signaling and media control, consolidated security, and management features. The SBC is in a sense a toolkit of functions such as Signaling Interworking, network hiding, security, quality of service (QoS), and much more.

The SBC facilitates simple and cost-effective connectivity between independent networks. It provides direct IP signaling and media interconnections, thereby lowering cost and performance latencies and improving media quality for multimedia sessions. Additionally, it offers greater flexibility in migrating from traditional time-division multiplexing (TDM) to unified communications services.

Challenges in Direct VoIP Interconnect

When a voice call connects from one service provider to another service provider, usually TDM interconnects are used. With the emergence of VoIP technologies, service providers started using IP connectivity to connect to other networks so that calls originating from an IP phone could stay on the packet network from end to end. Service providers then found new challenges in passing VoIP calls to other service providers.

Because VoIP subscribers can have unique environments with respect to protocols, IP addresses, codecs, the way they carry dual tone multifrequency (DTMF) traffic, etc., interconnecting two network domains can be very difficult. In addition, each provider wants to protect its own network from other providers' networks. Furthermore, service providers face other concerns with regard to call detail records (CDRs), billing records, quality of voice calls, troubleshooting, and feature interactions - all of which make end-to-end VoIP performance extremely challenging.

Role of SBC in VoIP Interconnect

VoIP, video streaming, instant messaging, multimedia conferencing, and interactive gaming are just some of the real-time, IP-based applications enjoying rapid growth in today's competitive communications market. Service providers are now finding it efficient and economical to directly interconnect their real-time VoIP and multimedia networks to their subscribers as well as to other service provider networks. This trend has created a requirement for SBCs to help service providers control and manage real-time multimedia communications sessions at the borders between their IP networks. In addition, SBCs are also useful for the following requirements:

  • Creating proper points of demarcation between service providers, or between enterprises and service providers, for manageability in the rich-media deployments such as VoIP and video
  • Hiding internal network topology from the peering partner or the outside world for security purposes
  • Using the SBC to provide interworking of protocols between H.323 and SIP, or between SIP and SIP (because of the rapidly changing standards and implementation of SIP)
  • Media transcoding, routing VoIP traffic to traverse firewalls, performing Network Address Translation (NAT) and Port Address Translation (PAT), and ensuring QoS

To overcome some challenges, devices such as SBCs are needed at various interconnect points.

SBCs are generally deployed in one of two models: unified and distributed deployment.

Complete Overview:


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