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

Softphones

• Internet phones

– Magic Jack

– Skype

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.