Computer Network Technology Chapter One
Ethernet:
Traditional Ethernet 10Mb/s
Fast Ethernet 100Mb/s
Gigabit Ethernet 10Gb/s
CSMA/CD : Collision Detection Carrier Sense Multiple Access, a ring access used within the subnet Control method
CSMA/CA: Conflict detection, carrier monitoring, multiple access, use ack signal to avoid conflicts.
Wide area network type
1. ISDN: Integrated Services Digital Network
2. PSTN: Public Switched Telephone Network
3. DDN: Digital Data Network
4.X.25: Packet Switching Network
5.FR: Frame Relay
6. ATM: Asynchronous Transfer Mode Network
7. Gigabit Ethernet GE and Optical Ethernet OE
FDDI : Optical fiber distributed data interface, the transmission medium is optical fiber, the transmission rate is 100Mb/s high speed, can be used in 100km range LAN, high reliability, large range LAN, supports dual loops, and has fast loop self-healing capabilities.
Three-layer structure of metropolitan area network: core layer, convergence layer, access layer
1. Core layer : data exchange, network interconnection, provide ip data interface, provide network services, extract routing services, connect multiple convergence layers, and provide network guarantee Qos ;
2. convergence layer : routing and traffic aggregation, traffic forwarding, data processing, tandem access layer, transmission convergence, forward switching, flow equalization, security control, route filtering, Qos management, security control, ip conversion;
3. access Entry layer : user access, flow control, connection to users, providing network information services;
management of broadband metropolitan area network: internal network management, out-of-band network management, and simultaneous management (both internal and external)
(1) Qos service:
(2) RSVP : Resource reservation
(3) Diffserv: Differentiated service
(4) MPLS: Multi-protocol label switching
PRP: Resilient packet ring
structure Features:
(1) Double ring structure
(2) Two-node bare fiber up to 100Km
(3) Within minutes Ring outer ring, inner ring counterclockwise, outer ring clockwise
(4) can realize ring self-healing, and can transmit data packets, control packets, and statistically multiplex the transmission of ip packets.
Technical features :
1. Each node executes SRP Fairness algorithm, equal bandwidth
2. Support weighted fairness rule, ingress and egress rate peak limit, guaranteed service
3. Double ring structure, limit data frame transmission mode, data frame recovery after successful transmission
4. Different services with different priorities
5. Self-healing ring and self-healing time within 50ms Three
networks integration : computer network, TV communication network, telecommunications communication network
Digital convergence : communication, computer, broadcasting, television industry convergence
Broadband access technology :
1 .xDSL: Digital Subscriber Line: According to the upstream (user to exchange) and downstream rate, it is divided into rate
stacking and asymmetrical a.ADSL asymmetric digital subscriber line: upstream 64 640kbit/s; downstream 500kbit 7Mbit/s
b. HDSL high bit rate digital subscriber line:
1.544Mbit /s symmetrical upstream and downstream c. RADSL rate adaptive digital subscriber line: upstream 64kbit/s 1.5Mbit/s downstream 640kbit/s 6Mbit/s
d.VDSL very high bit rate digital subscriber line ：Downlink 2.3Mbit/s 51Mbit/s Downlink 640kbit/s 6Mbit/s
2.HFC : Optical fiber and coaxial cable hybrid network
① Two-way transmission system
② Provides an Internet access method
③ Provides services to users through coaxial cable down leads
④ Shared transmission, all cable signal transmission and reception use the same uplink and downlink channel
⑤ Connect the calculator and the cable TV coaxial cable through Cable Modem
⑥ Cable Modem uses frequency division multiplexing method to divide the two-way channel into uplink and downlink channels
⑦ Cable Modem can be divided into two-way transmission into symmetrical and asymmetrical. The
symmetrical transmission rate is 2~4Mbit/s; the highest can reach 10Mbit/s
asymmetrical, the downlink rate is 30Mbit/s; the uplink rate is 500kbit/s ~2.56Mbit/s
3. Fiber access technology
(1) Fiber to the Curb (FTTC)
(2) Fiber to the Zone (FTTZ)
(3) Fiber to the building (Fiber to the Building, FTTB)
(4) Fiber to the Office (FTTO)
(5) Fiber to the Home (FTTH)
4. Local Area Network Access Technology
Passive Optical Network (PON)
Passive Optical Network Press The ITU standard can be divided into two parts:
a. (0C-3, 155.520Mbit/s symmetric business.
b. Uplink 0C-3, 155. 520Mbit/s; downlink OC 12, 622. 080Mbit/s asymmetric business 。
0C-n: Optical Carrier level n (optical carrier level). "0C" is the abbreviation of Optical Carrier, which is a unit of optical fiber transmission, it is usually expressed as 0C-n, where n is the multiplex transmission technology The basic rate is a multiple of 51. 84Mbit/s.
5. Wireless access technology: wireless LAN access, wireless metropolitan area network access, wireless AD hoc access
IFEE 802.11 defines the use of infrared, frequency hopping spread spectrum and direct sequence spread spectrum technology at a rate of 1 Mbit/s or 2Mbit/ s
IEEE 802. 11a rate is 54Mbit/s
IEEE 802.11b defines the use of direct sequence spread spectrum technology, the data transmission rate is 1Mbit/s 2Mbit/s. 5. 5Mbit/s and 11Mbit/s
wireless mesh network (Ad hoc) technology
Ad hoc technology has two development directions:--It is a wireless sensor network (WSN) based on the development and application of military and specific industries; the other is to develop into the field of civilian access networks, and there is a wireless mesh network. (WMN).
Wireless access technologies mainly include: WLAN, WiMAX, Wi-Fi, WMAN and Ad hoc, etc.