Basics of protocols

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(No Transcript)
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Basics of protocols

• David Duffett, Aculab

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Our agenda for today

• Introduction
• Background
• A quick game of which protocol am I?
• Strengths and weaknesses
• Real life examples

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But first a quick test

• Clasp your hands in front of your face
• Which thumb is closest to your face?
• Left thumb closest
• You are the sexy people
• Right thumb closest
• You think youre the sexy people

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Introduction

• What is a protocol?
• protocol    (pr? t? -kôl) n.
• The forms of ceremony and etiquette observed by
  diplomats and heads of state
• A preliminary draft or record of a transaction
• The plan for a course of medical treatment or for
  a scientific experiment
• Computer science a standard procedure for
  regulating data transmission between computers

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Introduction

• In the crazy world of VoIP
• We can generally take protocol to mean the way
  in which the calling and called end points must
  communicate with each other in order to set up,
  tear down and otherwise manage a session (call)
• There are a number of these protocols
• Even having two end points claiming to use the
  same protocol is not a guarantee of a working
  solution
• People interpret the standards for their own
  purposes

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Introduction
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Background

• As VoIP has developed, various protocols used for
  call control have appeared
• Telecoms standards bodies
• Internet standards bodies
• Individual developers trying to solve a problem
• Commercial entities

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Background

• For VoIP to work, both (all) the end points
  involved must use the same protocol for call
  control unless a gateway is in use

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Which protocol am I?

• Developed by a telecoms standards body
• Based on the tried and tested Q.931
• Adopted in early VoIP deployments, I am still
  very much in use today
• I am very efficient in that I use short codes for
  messages
• Some of the really big players developed their
  systems around me

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Yes Im H.323

• Developed by the ITU
• Very telecomsy way of doing things
• Good record on compatibility
• Cisco were heavy H.323 users
• Early protocol, but still very much in use
• Used for video sessions, as well as voice

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Which protocol am I?

• Developed by an Internet standards body
• Arrived at by successful RFCs
• Most VoIP developers talk about me
• I use messages that humans can easily understand
• Some backbone networks are based on me
• I am very flexible, useable for more than just
  voice

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Yes Im SIP (session initiation protocol)

• Developed by the IETF
• People contribute RFCs, once agreed they become
  part of the standard
• Probably more SIP end points than anything else
• BTs 21CN is based on SIP
• Amazing potential with 3PCC (third party call
  control)
• The initiated session may be used for voice

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Which protocol am I?

• Originally developed by an individual
• My name references an Open Source PBX
• I am bandwidth efficient
• A lot of end points are capable of supporting me,
  even though the big players dont yet use me

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Yes Im IAX2 (pronounced eeks)

• Originally developed by Jared Smith, an Asterisk
  developer
• Full name is Inter-Asterisk eXchange version 2
• Ongoing development encouraged within the Open
  Source community
• Aggregates RTP payloads together in order to make
  more efficient use of the packet headers, and
  therefore bandwidth

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Which protocol am I?

• Developed by a commercial organisation
• I am probably the most widely used protocol today
• I have been described as a car with hood welded
  shut
• I enable peer-to-peer voice and video
  communications
• I am probably the most widely known VoIP brand

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Yes Im the Skype protocol

• Developed around 2003 by the people that brought
  us the KaZaa file sharing service
• Uses an overlay peer-to-peer network made of
  ordinary hosts and supernodes
• Very little is known of the details of the
  protocol
• Great at traversing NATs and firewalls
• Over 100,000,000 downloads to date

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Real life situations

• Person away on business wants to communicate with
  their spouse from hotel room
• Skype would allow voice and video
• Same person wants to call normal landlines
• Skype Out (costs)
• ATA using IAX2 would remove NAT hassles
• Telco wants multi-functional network and the
  ability to separate voice and call control
  signalling
• SIP

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In summary

• VoIP call control protocols are used to set up,
  tear down and otherwise manage calls
• H.323 well deployed, but not seen as the future
• SIP all the talk is SIP, has trouble with NATs
  and firewalls
• IAX2 popular with Asterisk installations, on
  the ascendancy and bandwidth-efficient
• Skype the most popular, but bespoke and only
  for peer-to-peer

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In summary

• Choice of protocol must be a function of
  requirements, both now and in the future
• Safe bet is to go with equipment that can support
  multiple protocols and codecs

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Thank you

• david.duffett_at_aculab.com

See us at booth 115