1.12 Network Facts

 

• Speeds often measured in bps (bits per second) but we are more interested in the bytes per second. There is approximately an 11:1 ratio.

T1 is 1.544 Mbps

T3 is 44.54 Mbps

 

• Network transmission,

baseband - single frequency- only one station may transmit at any time (Ethernet, ARCnet, Token ring). These must be in discrete digital packets.

boradband - multiple frequencies allow multiple simultaneous data streams. This network can reach higher speeds by multiplexing and can have continuous and/or analog channels (ISDN, CATV,ATM)

 

• Networks are some mix of clients and servers.

server - will share reseaources (eg, files) with many remote computers

client - a computer that typically talks to a limited number of servers

 

• Token based networks rotate talk permissions between machines by passing a “token”

 

• ARCnet - a token passing network that is relatively immune to noise

 

• IBM token ring - a star topology token passing network

 

• FDDI - fiber based token passing rings that rotate in opposite directions

 

• Ethernet - both bus and star topologies

 

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