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Voice and Video over IP
Topics
• Use Terminology specific to converged networks
• Explain VoIP• Explain video over IP• Describe VoIP and video over IP
signaling and transport protocols• Understand QoS
Terminology
• IP telephony:– Carries VoIP over TCP/IP network.
• VoATM:– When using VoIP over an ATM network.
• VoDSL:– When using VoIP over a DSL network
• FoIP:– Fax using TCP/IP network.
• Video Conferencing• Streaming video• Webcasts• IPTV
VoIP Applications and Interfaces
• Advantages:– Lower costs– New or enhanced features and
applications– Centralize voice and data network
management
Analog Telephones
• Works like a dial up connection.– Signals must be converted from
digital to analog.– One way is using a ATA (analog
telephone adapter).– Second way is connecting an
analog telephone to a switch, router, or gateway capable of accepting analog voice signals, converting them into packets.
Analog Telephones
– Third is an analog-to-digital voice conversion device (IP-PBX).
– Fourth is the traditional phone connection to an analog PBX.
– Vonage
Video over IP Applications and Interfaces
• Cisco Systems, the largest supplier of networking hardware, estimates that by 2011, 60% of the traffic carried by the Internet will be video traffic.
• Three Categories:– Streaming video– IPTV– Videoconferencing
Streaming Video
• YouTube is an example• Two ways of providing this:
– Video-on-demand– Live streaming video
• Examples of both Public and Private.– YouTube videos– TV episodes on Hulu.com
IPTV
• Best example of this is Telus TV.• Set Top Boxes:
– Google TV
– HD IPTV Nuclius
– Boxiee
– Celrun
Videoconferencing
• This now provides a means of interaction.– Telemedicine– Tele-education– Judicial proceedings– Surveillance
Signaling Protocols
• Some functions performed include:– Requesting a call– Locating clients– Acknowledging a request– Managing ringing, dial tone, call waiting– Detecting and reestablishing dropped
calls– Properly terminating a call
H.323
• ITU standard that describes an architecture and a group of protocols for establishing and managing multimedia sessions on a packet-switched network.
• Key elements include:– Terminal– Gateway– Gatekeeper (the nerve centre)– MCU (multipoint control unit)– Zone
SIP (Session Initiation Protocol)
• A protocol that performs functions similar to those performed by H.323
• Modeled on the HTTP protocol.
• SIP’s capabilities are:– Determining the location of an endpoint.
– Determining the availability of an endpoint.
– Establishing a session between the endpoints
– Negotiating features of a call
– Changing features of a call
Transport Protocols
• RTP (Real-Time Transport Protocol)– RFC1889, at the application layer relies on
UDP at the transport layer.
• RTCP (Real-Time Transport Control Protocol)– RFC 3550, provides feedback on the quality
of a call.
• Although RTP and RTCP provide information about the packet order, loss, and delay, they cannot correct transmission flaws
QoS Assurance
• This measures how well a network service matches its expected performance.
• Three techniques standardized by IETF– RSVP (Resource Reservation Protocol)
• RFC 2205 a transport lay protocol– DiffServ (Differentiated Service)
• Because of its simplicity and low overhead, it is better suited to large networks.
– MPLS (Multiprotocol Label Switching)• Contains information about where the
router should forward the packets.