CS335 Networking & Network Administration Tuesday, June 1, 2010

IP telephony Equipment is less costly than telephone switches Backward compatible with PSTN (public switched telephone network) Be able to work with calls that originate with PSTN and terminate with IP telephone and vice versa

Encoding Audio is encoded using Pulse Code Modulation (PCM) The digitized audio is transferred using Real- Time Transport Protocol (RTP) – RTP solves some of the problems of duplication, jitter, and out of order delivery Each RTP message is encapsulated in UDP datagram, which is further encapsulated in IP datagram

Basic IP telephone system IP telephone Media Gateway Controller

Interoperation Media Gateway Signaling gateway

SIP – Session Initiation Protocol Operates at application layer Encompasses all aspects of signaling, including location of a called party, notification and setup (ringing a phone), determination of availability, and termination Provides services such as call forwarding Relies on multicast for conference calls Allows the two sides to negotiate capabilities and choose the media and parameters to be used

Example SIP session

IP telephones and electrical power Analog phones don’t need power IP telephones need power also Power over ethernet

FTP BSD UNIX

FTP Establish connection Authorize Put or Get files List files cd, cdup, ls

File types Binary Text Verbose and quiet mode

TFTP Trivial file transfer protocol Uses udp Devices use this to update software to devices like switches, routers, etc.

NSF - Network File System Accommodates applications that only need to read or write a part of a file Integrated into a computer’s file system view.html view.html

WWW Browsing http https Html Xml Web caching

Dynamic Web CGI ASP JSP PHP Lasso Cold Fusion Java Javascript

RPC Remote Procedure Call Places procedures on more than one machine

RPC Remote

RPC Communication stubs – software to implement the RPC

Middleware ONC RPC CDE/RPC MSRPC CORBA MSRPC2 COM/DCOM JINI SOAP XML

RPC letin/MS mspx letin/MS mspx inition/0,,sid26_gci214272,00.html inition/0,,sid26_gci214272,00.html