TYPES OF WAN :: (TECHNOLOGIES OF WAN) IMP
using components such as bridges & routers etc , lan can be expanded to wan
- CIRCUIT SWITCHING ::
''Dedicated communications path established for the duration of a connection.''
i.e to select one way from many ways & switch over to that part .
LOGICAL PATH :: all the routs available from source to destination
DEDICATED PATH :: the way which we select outof all logical paths s known as dedicated path
data is transferred from source to 1st node where it is checked for errors, if that data is fine then it's transferred to next node & a copy of it is kept here on 1st node (for if data become corrupted on 2nd node )…but if the data is corrupted on 1st node then it s moved back to the source for correcting that…e,g telephone network
- PACKET SWITCHING ::
data s trasferred on dedicated path in form of packets/chunks of variable (different)size.
every packet is data by it self..data packet is transferred to node then it decided where it will go
then all packets r receieved
at destination & r oredered
wth every data packet 12 bits r attached on each side of packet ..1st 12 bits r known as header
last 12 bits r known as trailer
these 12 bits contain :: source info , dest info , error checking
theses two 12 bits makes data tranfer slow the max speed is 64 kb
e,g terminal to computer & computer to computer communications.
- FRAME RELAY ::
only ist packet will have header & the last packet of trailer ..attaching a 8-12 bit overhead to every packet maked data trasferr rate very slow so in frame relay was made .it's also a packet-switiching network service but the advancement was that it used fiber-optic networks.12mb(bits)ps..
- ATM (ASYNCHRONOUS TRANSFERR MODE)
same rule as frame relay & packet switching
but the size of packets would be of equal size & they would be called cells not chunks ,,,max speed 10 -100 mb/s
synchronous means : when 2 things have same speed & time period
- ISDN ::integrated services digital network
data & telephone r integrated on same line one connection speed no busy signal
two types r ::::
narrow band : 64 kbps
broad band : 100 kbps
FDDI : FIBER DISTRIBUTED DATA INTERFACE
SONET : SYNCHRONOUS OPTICAL NETWORK..uses fiber optic technology , more than 1Gbps.
SMDS : SWITCHED MULTIMEGABIT DATA SERVICE…uses the fixed length cell relay technology as ATM..