When examining the communications infrastructure and the major problems that are associated with using current technologies we see that the point of new technology is to over come deficiencies of current technologies.
The world is moving at fast pace, processors and applications just keep getting faster and faster, so we look at data communications and how it can improve the movement of information within a networked environment.
This chapter gives the general overview of the emerging technology to meet needs of applications.
Needs for Services
The Past
Development of high-speed inexpensive computers to meet the needs of the average person. This opened a vista to new powerful application. Examples of the applications that may be used are interactive real-time simulations, three dimensional modeling and color images.
The T1/E1 Legacies
1970s & 1980s = 1.5 to 2.048 Mbs
- T1/E1 meet the needs for most user applications
VPN - Share communications channels with other users
Switches - Relay traffic from multiple users.
Frame Relay fast packet service
-Lets the user support error recovery
-bandwidth and demand services
-data applications and some voice applications
-Suppose to solve WAN bottle neck services
MAN IEEE Standard 802.6
-distributed queue dual bus (DQDB) protocol to support integraded networks for multimedia applications
-interconnects LANs accross WANs
Switched Multimegabit Data Service (SMDS)
-Relies on the MAN technologies
-provides public high-speed transport system US and Eurpose
Services - highspeed ata applications that require bursts for high-speed data applications that require bursts of high bandwidth transmission for applications.
Such as, file transfer, CADéCAM, and imaging.
Asynchronous Transfer Mode
- part of B-ISDN solution
- cell relay technology
includes - high speed
- multiplexing and switching services for voice, data and video applications
Cell in ATM and IEEE 802.6 (MAN)
802.6 = basis of SMDS
CELL vs FR
Cell at the CPE a computer or PBX
which can be variable
is - segmented into smaller fixed length units called cells
5 header 48 payload
Supports transmission and reception of voice, video data and other applications
Interests = Large companies that have developed multiple networks to handle transmission schemes.
Why do we prefer cell
Cell is better then variable length frames, which provides the delay to be predictable in fixed length frames with the performance in the network then with variable length frames
-ATM queuing is done inside switch
-Fixed length buffers more easier to manage then variable.
-Cell relay has superior Quality of Service.
Wide spread commercial inception of computer and communication's networks in the 1960`s
1970`s - Communications archietecture was all software
Typically
Physical Layer = hardware
Datalink Layer = software
Late 1970`s early 1980`s
implemented into hardware some of the Data Link functions
Fostered HDLC which would
lead to -Link Access Procedure Balanced (LAPB)
-Link Access Procedure For the D channel (LAPD)
-Chip sets and firmware
Thats all I am going to introduce for now next post will continue Chapter 1, in later chapters Uyless Black goes into detail with every protocol mentioned here and that will be in next post. So don`t be to overwhelmed, I know I was the first time I read half the book.
Little note to me: Ch1 Pg5
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