2. SBC - Session Border Control

Crosslynx - Session Border Controller


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NAT Traversal Solutionl


iPICO Mobile SIP Client                     PICO Mobile SIP Client


NAT firewall traversal represents the single largest barrier to your success as a VoIP provider. WWWT’s CrossLynx has overcome that barrier. It allows all SIPend-point devices to traverse NATS without compromising on security and ensures reliable VoIP services to customers.


WWWT’s CrossLynx is a standard based SBC (Session Border Controller), a highly integrated software package that allows all SIP end-point devices to traverse NATS irrespective of the end point’s NAT awareness capabilitiy. NGNs (Next Generation Networks) and other VoIP service providers now have a highly scalable solution to this increasingly pervasive network problem at a low entry level price.


WWWT’s CrossLynx is compliant with the latest SIP specification standard – RFC 3261. It provides a highly scalable, load balanced solution with failover in a highly distributed architecture.


WWWT's CrossLynx is based on two component parts:


  • WWWT’s CrossLynx is based on two component parts:

  • Outbound SIP Proxy server
  • Media Relay

Outbound SIP Proxy Server with Media Relay Configuration - SBC


Outbound SIP Proxy Server

The Outbound SIP Proxy server module is composed of a SIP proxy server, a SIP registrar server and a SIP B2BUA (Back to Back User agent).


This specialized SIP Proxy Server detects SIP UAs (User Agents) NAT/Firewall status. It is based on the SIP proxy architeture with protocol level interoperability.


For NAT aware SIP clients, it acts as a SIP proxy server.


For non NAT aware SIP clients or for SIP clients behind symmetric NATs ro firewalls, it acts as a dialog stateful proxy (B2BUA), rewriting specific data in the SIP message.

Media Relay

The media relay component is composed of a high performance IP packet routing and a controller application interface.


The media relay supports multiple network interfaces and provides real time statistics.

It has a configurable bandwidth capacity and is scalable for any number of relays (typical sizes are 200-500 relays per server).

Advanced applications of the media relay include:


  • RTP (voice/video/IM) relay

  • Media Recording

  • Codec Transcoding

CrossLynx Benefits:


  • Scalable redundancy with failover capabilities

  • Fully integrated with SIP proxies and SIP application servers

  • Agnostic to the capabilities of the SIP end point

Specifications

NATs & Firewalls Supported


  • Residential-style firewalls
  • Strong, corporate firewalls
  • Full Cone NAT
  • Restricted NAT
  • Port Restricted NAT
  • Symmetric NAT
  • Multiple nested NAT of all kinds

General

User Agents Supported


SIP hard phones

SIP soft phones

SIP video phones

SIP presence/IM agents

Analog Terminal Adaptors (ATAs)

Other endpoints (ie: gateways) with registration capability or not (using ACL)


Underlying Technology

SIP Proxy Server

SIP Registrar Server

SIP Location Server

Back to Back User Agent for SIP

Back to Back Media Relay for RTP and RTCP


Management

Web Base Monitoring and Statistics

Packet Routing Statistics

Signaling Protocols

  • SIP (RFC2543, RFC3261)
  • and SIP extensions
  • SDP (RFC 2327)

Media Relay Features

Media Protocols

RTP (RFC1889, RFC3550 - Including encryption)

RTCP (RFC1889, RFC3550 – Including encryption)

Derivatives relying on RTP and RTCP (eg: RFC2833)

for DTMF

VoIP/Calls Supported

  • Audio
  • Video
  • Multi media
  • Instant Messaging
  • Presence



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