Chapter IV, LAN technology
Test sites 1, a transmission medium
Test method [analysis]
This test method is a test center substantially twisted pair, fiber concept and usage scenarios
Points [analysis]
1, the twisted pair transmission range within 100m, a total of four pairs of the core, wherein the core for transmitting data 1,2, 3,6 number core for receiving data. The remaining number 4,5,7,8 core is not being used
2, a plurality of multimode fiber angles from the incident light, which is thicker than the single-mode fiber core, cheaper than the single mode optical fiber, using an LED lamp as the light source, the maximum transmission distance of 550m
3, single-mode fiber to a single incident angle of the light, its core, more expensive than multimode fiber thinner than multimode fiber, using a laser as the light source, the transmission distance is greater than 550m
Remarks [coaching]
Memory knowledge points to keep in mind
Test sites 2, CSMA / CD protocol
Test method [analysis]
This test method is a test center substantially Comparative Carrier Sense three algorithms, and the minimum frame length of the data frame request
Points [analysis]
1, the carrier sense algorithm:
Non-stick type monitor algorithms: link utilization is low, the probability of conflict is low
1- adhere to monitor algorithm type: high link utilization, the probability of conflict is high
P- adhere to monitor algorithm type: high link utilization, low probability of conflict
2, the shortest frame length formula to keep in mind: sending delay $ \ geq2 $ propagation delay times
Remarks [coaching]
Monitor algorithm is conceptual knowledge points to keep in mind. For the calculation of the shortest frame length, generally only need to apply the formula.
3 test sites, the Ethernet frame format
Test method [analysis]
This test method is a basic test sites and the length of the MTU of an Ethernet frame
Points [analysis]
1, an Ethernet, the minimum frame length is 64 bytes, the maximum length is 1518 bytes
2, Ethernet, the data portion of the frame occupy bytes 46-1500
3, Ethernet, frame data MTU size is 1500 bytes, i.e. the maximum transmission unit MTU, i.e. the maximum length of the data portion of the data frame
Remarks [coaching]
Memory knowledge points to keep in mind
4 test sites, high-speed Ethernet
Test method [analysis]
This test method is a test center basic medium used in different standard Ethernet Type
Points [analysis]
| Ethernet species |
Transmission medium |
| 10BASE-T |
Twisted Pair (UTP-CAT3-5) |
| 10BASE-F |
Multimode fiber |
| 100BASE-TX |
Twisted Pair (UTP-CAT5 / STP) |
| 100BASE-T4 |
Twisted Pair (UTP-CAT3-5) |
| 100BASE-FX |
Multimode fiber |
| 1000BASE-SX |
Multimode fiber |
| 1000BASE-LX |
Multi-mode / single-mode fiber |
| 1000BASE-CX |
Shielded copper wire |
| 1000BASE-T |
Twisted Pair (UTP-CAT5) |
Remarks [coaching]
Memory of knowledge, understanding can do
5 test sites, conflict and broadcast domains
Test method [analysis]
This test method is a test center basic topology number given by the determination of a conflict and broadcast domains
Points [analysis]
1, the collision domain is a region transmit electrical signals conflicts
2, broadcast domain means a range of a broadcast frame can reach
3, All-port hub (HUB) are in the same collision domain, a port switch (SWITCH) is a collision domain router (ROUTE) is a port of a broadcast domain
Remarks [coaching]
Memory knowledge points to keep in mind
6 test sites, the working principle of the switch
Test method [analysis]
This test center to test the basic method is to understand the basic principles of the work process switch
Points [analysis]
1, the switch during operation, maintains a port -MAC address mapping table
2, frame data received through the switch to learn the source MAC address
3, the switch forwards the data received by the destination MAC address of the frame
4, Port -MAC address mapping table entries will not exist long. When an entry in the data frame is still not through 300s, the source can not receive MAC data frame is the entry, then the entry is deleted in the mapping table
Remarks [coaching]
Memory knowledge points to keep in mind
Test sites 7, VLAN virtual local area network technology
Test method [analysis]
This examination test center in the morning and afternoon exams may be related to the general study of the role of VLAN, VLAN division methods, scope and value of the VLAN to the type of interface
Points [analysis]
1, the role of the VLAN: effective control of the broadcast domain range (isolation broadcast), enhance the security of local area networks (operational security), Flexible virtual workgroup (planning, routing flexibility)
2, VLAN division manner: static and dynamic partitioning partitioning port based on the MAC address, protocol, etc. subnets
3, VLAN range of values is 1-4094,0 and make reservations 4095
4, VLAN interface type has access, trunk (usually two types of test) and hybird. Access through opening allowing only one vlan, trunk interfaces, by allowing multiple vlan.
5, an encapsulation protocol is used trunk IEEE802.1q
6, the communication between the three devices need to use VLAN
Remarks [coaching]
Memory knowledge points to keep in mind
Test sites 8, GVRP
Test method [analysis]
This basic test sites test to know if the receiving condition GVRP ports in the respective modes of the information vlan
Points [analysis]
1, normal mode: to allow the port to dynamically register or deregister VLAN, dynamic VLAN and propagate static VLAN information
2, fixed pattern: Disables the port to dynamically register or deregister VLAN, propagates only static VLAN, dynamic VLAN information is not propagated
3, forbidden mode: Disables the port to dynamically register or deregister VLAN, and to propagate VLAN information except to VLAN1
Remarks [coaching]
Memory knowledge points to keep in mind, since this is a new test center after the official textbook revision content, so the true problem is not too much, but need to know
Test sites 9, STP Spanning Tree Protocol
Test method [analysis]
This test method is a test center substantially the basic concepts and principles of the Spanning Tree Protocol, given topology and usage scenario type determination port
Points [analysis]
1, the spanning tree protocol a physical ring network, by blocking one or more logical ports, form a tree structure of a logical network
2, the bridge ID for selecting the root bridge, the bridge priority bridge ID and mac address components, the smaller the priority bridge ID
3, the bridge priority from 0 to 65535, the default value is 32768, to modify the bridge priority to grow in multiples of 4096
4, the root bridge is selected after completion, then select the root ports and designated ports. Root port is on a non-root bridge, rather than on the root bridge. Root port information is used to receive the root bridge port, designated port is used to send information to the root bridge port.
5, is 802.1d standard Spanning Tree Protocol
Remarks [coaching]
This conceptual knowledge and logic more content, it is recommended to do by learning the knowledge Zhenti
10 test sites, wireless local area network
Test method [analysis]
This test center to test the basic law is the wireless LAN standard, using the protocol and how to ensure the security of wireless local area network
Points [analysis]
1, there are multiple wireless LAN standards. Usually investigated under various standards and frequency bands corresponding to the operation speed.
IEEE802.11b and 11g running band, 802.11a operating in the 2.4GHz band, 802.11n 5GHz running in the 2.4GHz and 5GHz bands.
802.11n rate is generally up to 300Mbps, combined use of MIMO and OFDM technologies, can theoretically reach 600Mbps.
2, the wireless LAN using CSMA / CA protocol, rather than CSMA / CD protocol
3, wireless LAN encryption algorithms are WEP, WPA and WPA2, in order to increase security
Remarks [coaching]
Memory knowledge, study in general is not difficult. Topics usually appear in the morning exam more
11 test sites, integrated wiring technology
Test method [analysis]
This test center to test the basic law is the basis of the concept of integrated wiring technology
Points [analysis]
1, integrated wiring technology has six subsystems
Work area subsystem: the cable between the subsystems work zone information socket
Level subsystems: the wiring distribution frame to each floor between the cable outlet between the working area information is installed
Management subsystem: floor management subsystem within a variety of devices
Trunk subsystems: subsystem implemented attached Floors
Subsystem devices: the installation of large centralized equipment places
Complex subsystems: subsystem connected to each of the building
Remarks [coaching]
Memory of knowledge, the above can be done to understand