Computer network (top-down method) Learning notes 1.2 network Edge

1. End system = Host. The host is divided into clients (client and server)
2. Black box: Routers, other detailed member links and Internet services.

3.C/S and P2 are two architectures.
4. Access network:
(1) Residential access:
a.pc-Dial-up modem (converts a digital signal to an analog signal for transmission over a telephone line)-Phone line-isp modem (converts analog signal to digital signal)-ISP router
(Slow (much less than 56kbps) and cannot call and surf the Internet at the same time)
B.DSL (short-distance transmission between residential and ISP modems): Similar to a dial-up modem, transmission of data in two directions has an incorrect claim.
Communication Link Partitioning:
Fast downlink channel (50khz-1mhz band)
Medium-speed upstream channel (4khz-50khz)
Common bidirectional telephone channel (0-4khz)
(The higher the frequency, the greater the amount of information carried)
C.HFC: Optical Cables-Cable Modems (Ethernet port)-Home PC

Important features (shared broadcast media. The number of active users determines the upstream and downstream rates)

D. Satellite link
(2) Company access: End user-edge router-local area network (LAN)
LAN technology is most prevalent in Ethernet technology (shared Ethernet and switched Ethernet).
(3) Wireless access:
Wireless LAN: Wireless User-base station-wired Internet (WiFi in university)

Wide Area Wireless access network: Wireless user-base station (Telecom)-Wireless internet (3G)

4. Physical media:
(1) Conductor type: Optical cable, twisted pair copper wire, coaxial cable
(2) Non-conductor type: Air and outer space (radio waves)


Twisted-pair copper wire: LAN dial modulation and demodulation technology DSL
Coaxial Cable: HFC
Optical Cable: long-distance transmission

Terrestrial radio channel: Wireless LAN technology-wide area radio channel for WLAN and cellular access technology
Satellite Radio channels: Accelerated Reproduction (Gbps), long delay (280ms)

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Computer network (top-down approach) Learning notes 1.2 network edge