Network administrator Knowledge points (2)

Comparison of baseband systems and broadband systems

(1) Baseband system

Advantages: Do not need modem, low price, structure, technology simple, easy to install;

Disadvantages: only one channel; limited capacity; limited distance;

(2) Broadband system

Advantages: Large capacity, multiple communication modes, flexible structure, large coverage range, and mature CATV.

Disadvantages: Need modem, expensive, installation and maintenance complex, two times the propagation delay.

I. IEEE802.3 Local Area network

(1) IEEE802.3 is a local area network that supports the CSMA/CD algorithm, the most commonly used baseband IEEE802.3 LAN has four kinds:

A.10base5

B.10base2

C.10base-t

D.10base-f

two. Ring Type network

1. Ring Type Network Working principle

(1) Repeater provides three basic functions of ring network: Data inserting ring, receiving data, deleting data from ring

(2) The method of deleting the message into the ring:

A. When a message is received by the destination station, the message is removed from the ring at the destination station;

B. The destination station receives the greeting, the message is still in the ring, until the return to the sending station to delete the message, this method has three advantages:

A. Relative to the first method, you can reduce the delay generated in order to identify the address as a delay;

B. A sign that changes the message from the receiving station, which is sent back to the transmitter to answer the response;

C. Allow multi-point broadcasts.

(3) repeater in the ring-type network operation of four states

A. Listening Status:

B. Send Status

C. Receive Status

D. Bypass state

three. Tag Ring media access Control

(1) Marker ring three different change schemes

A. The number of messages that can be sent when the site obtains control marks;

B. The situation and position of the control mark are contained within the information frame or outside the information frame;

C. When the sending station releases the tag to the next site.

(2) Three kinds of marking ring network: Dcs,esm,prime

(3) The greatest advantage of the ring topology is that the transmitted signal is regenerated at each node due to the use of point-to-points communication links , so

Transmission errors can be minimized, and the transmission distance of the entire network can be very long. The ring-type structure of point-to communication can adopt fiber as transmission medium,

It has the advantages of high speed and strong anti-jamming ability. The biggest drawback is the reliability issue.

For more information, please go to the Greek school of soft exams.

Network administrator Knowledge points (2)