Monday, July 12, 2010

Networks specifications

Computers communicate over networks using unique addresses assigned by system software. A computer message, called a packet, frame, or datagram, includes the address of the destination computer and the sender’s return address. The three most common types of networks are broadcast, point-to-point, and switched. Once popular token-based networks (such as FDDI and token ring) are rarely seen anymore.

Speed is critical to the proper functioning of the Internet. Newer specifications (cat 6 and cat 7) are being standardized for 1000BaseT (1 gigabit per second, called gigabit Ethernet, or GIG-E) and faster networking. Some of the networks that form the backbone of the Internet run at speeds of almost 10 gigabits per second (OC192) to accommodate the ever-increasing demand for network services.


Network specifications
DS0
64 kilobits per second

ISDN
Two DS0 lines plus signaling (16 kilobits per second) or 128 kilobits per second

T-1
1.544 megabits per second (24 DS0 lines)

T-3
43.232 megabits per second (28 T-1s)

OC3
155 megabits per second (100 T-1s)

OC12
622 megabits per second (4 OC3s)

OC48
2.5 gigabits per seconds (4 OC12s)

OC192
9.6 gigabits per second (4 OC48s)

Source of Information : Prentice Hall A Practical Guide to Fedora and Red Hat Enterprise Linux 5th Edition

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