The third chapter, network architecture
1, network performance - Calculation delay
Test method [analysis]
The test sites generally present method is to find a test data frame sent from station A to station B receives the total time used
Points [analysis]
1, T total delay = T + T transmission propagation delay
2, T = transmission delay of the data frame / data rate refers to a data frame sent from the first bit to the last bit sent with the time
3, T = the propagation delay of the link length / propagation rate data frames on the link, a data frame refers to the propagation time on the link
4, a data frame on the circuit propagation velocity of light is two thirds i.e. $ 2 $ * 10 ^ 8 m / s, sometimes this condition does not inform the subject, bearing in mind
Remarks [coaching]
Apply Math
2, OSI model and the TCP / IP model
Test method [analysis]
This method involves examination of the test sites at various levels of the OSI model and the effect of the corresponding protocol, and various protocols encapsulated relationship between
Points [analysis]
| level |
name |
The main function |
Major equipment and protocols |
| 7 |
Application layer |
The achievement of specific application functions |
POP3、FTP、HTTP、Telnet、SMTP、DHCP、TFTP、SNMP、DNS |
| 6 |
Presentation layer |
Expression data format, encryption, compression |
|
| 5 |
Session Layer |
Build, manage and terminate sessions |
|
| 4 |
Transport Layer |
To-end connection |
TCP、UDP |
| 3 |
Network layer |
And routing the packet transmission |
Three switches, routers ARP, RARP, IP, ICMP, IGMP |
| 2 |
data link layer |
Transmitting information in units of frames |
Bridges, switches (multiport bridges), network card, PPTP, L2TP, SLIP, PPP |
| 1 |
Physical Layer |
Binary transfer |
Repeaters, hubs (multi-port repeaters) |
Remarks [coaching]
Memory above table