Chapter V, wide area network and access network technology
1 test sites, WAN exchange
Test method [analysis]
The basic features of the present test method is a test sites were able to exchange a variety of
Points [analysis]
1, exchange circuit switched and packet switched
2, there datagram packet switching exchange, exchange virtual link and the cell exchange
3, the cell switching and virtual links need to establish a virtual connection, and the data packets do not need to exchange
4, the virtual link switching, the network is a frame relay network typically two (operating in the second layer) and the X.25 network (in the third working layer)
Remarks [coaching]
Memory of knowledge, we can understand
2 test sites, a common wide area network protocols
Test method [analysis]
This test center test method is to examine the basic HDLC and PPP protocol basic concepts
Points [analysis]
1, HDLC is a high-level data link control protocol A widely bit-oriented, a Cisco proprietary protocol.
2, HDLC 01111110 used as a frame boundary, will be used to zero bit stuffing method
3, PPP protocol is developed in HDLC, character-oriented protocol
4, the frame contains the PPP LCP packet and NCP packet. LCP packets to establish, configure, and test the data link connection verification, the NCP packet establishing and configuring different network-layer protocols
5, PPP protocol frame with an optional authentication protocols: PAP and CHAP, wherein the safety CHAP, using the 3-way handshake
Remarks [coaching]
Memory of knowledge, we can understand
Test sites 3, SONET / SDH
Test method [analysis]
This test method is a test center examine basic SONET / SDH signal corresponding to each rate
Points [analysis]
Remarks [coaching]
Rate memory knowledge, the main memory STS (OC) -1/3 and the STM-1 can be
4 test sites, access network technology -xDSL
Test method [analysis]
This test center to test the basic law is the basic concept of the study xDSL
Points [analysis]
1, xDSL is a generic term for a variety of Digital Subscriber Line DSL, by using frequency division multiplexing, the digital data utilizing telephone lines
2, channel ADSL, VDSL, RADSL asymmetric.
3, HDSL, SDSL is symmetric channel
Remarks [coaching]
X is A / V is an asymmetric channel, the rest channel is symmetrical
5 test sites, access network technology -HFC
Test method [analysis]
This test method is a test center substantially HFC examine the basic concepts
Points [analysis]
1, HFC network is a hybrid fiber coax
2, HFC cable modem using modem
3, the access from the operator to the user fiber cell is used, access to the user from the cell using a coaxial cable
Remarks [coaching]
Memory of knowledge, we can understand
6 test sites, access network technology - Optical Access Network
Test method [analysis]
The basic test method of the present test sites is the basic concept of optical fiber access network visits
Points [analysis]
1, PON (passive optical network) by the optical line terminal (OLT), an optical distribution network (ODN), an optical network unit (ONU) Composition
2, the use of multipoint mode, which broadcasts the downlink, using an uplink TDMA TDMA
3, the flexibility to form a tree, star, bus topology, etc. (a typical tree structure)
4, according to the position of the ONU, and the investment of different application types, divided FTTH (fiber to the home), FTTC, FTTB, FTTZ.
5, the difference between the active optical network: the main features of a passive optical network (PON) is used in all ODN passive optical components, active devices to avoid electromagnetic interference and lightning effects, reducing the failure rate of the external lines and equipment , engage in high system reliability
Remarks [coaching]
Memory of knowledge, we can understand