Wednesday, April 23, 2008

Network Media

The common problems on the Network Media are:
* Attenuation is signal degradation due to capacitance, conductance, and resistance over distance.
* Crosstalk occurs when the signal from one cable affects the signal on a nearby cable.
* Noise is erroneous signal that is present on the media.
* Eavesdropping is a security problem that happens when data signals are intercepted.

The most dangerous to the less dangerous mediums are:
* Wireless
* Coaxial
* Fiber optics

* Shielding
* Padding


Is highly susceptible to attenuation, crosstalk, and noise.
Is highly vulnerable to eavesdropping. You must encrypt wireless traffic to protect it from interception.


Is not suitable for ring or star topologies because the ends of the cable must be terminated.
Are rarely used in modern networks. Coaxial is difficult to install and maintain.
Types: 10Base5 (ThickNet) and 10Base2 or (ThinNet).

Twisted Pair

Shielded Twisted Pair (STP) has a grounded outer copper shield (or foil) around the bundle of twisted pairs or around each pair. This provides added protection against EMI.

Unshielded Twisted Pair (UTP) does not have a grounded outer copper shield. UTP cables are easier to work with and are less expensive than shielded cables.

Cat 2 is used with 4 megabit Ethernet.
Cat 3 is used with 10 megabit Ethernet or 16 megabit Token Ring.
Cat 4 is used with 16 megabits Token Ring or token bus.
Cat 5 is used with 100 megabit and 1 Gigabit Ethernet and ATM networking.
Cat 5e is similar to Cat 5 but provides better EMI protection. Cat 5e supports 1 and 10 Gigabit Ethernet (Gigabit connections require the use of all four twisted pairs).
Cat 6 is designed for high-bandwidth, broadband communications such as full-motion video.

Fiber Optic

It is made of plastic or glass.
* he core carries the signal. It is made of plastic or glass.
* The cladding maintains the signal in the center of the core as the cable bends.
* The sheathing protects the cladding and the core.

Fiber optic cables are classified as one of two types:

* Single mode cables use a single light ray. The core diameter is around 10 microns. Cable lengths can extend a great distance (less attenuation).
* Multi-mode cables use multiple light rays in a single cable. The core diameter is around 50 to 100 microns. Cable lengths are limited in distance (higher attenuation).

Fiber optic cables:

* Allow for very high speeds and high bandwidth.
* Are immune from crosstalk and noise.
* Allow for greater distances than wireless or other wired media.
* Require specialized equipment to tap, making eavesdropping difficult.

1 comment:

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