Candidates for communication questions and answers from various Huawei Engineers (IV)

Short answer

1. According to the new national standard, briefly describe China's new telephone network level structure

China's telephone network has gradually evolved from Level 5 to Level 3. The new level structure is long distance, level 1 switch center DC1 and level 2 switch center DC2; Local Level 2, the DTM of the Exchange Center and the DL Of the exchange center.

2. Briefly describe network organizations suitable for large cities and large cities

The partition structure is used. Divide the local network into several settlement zones, and set up two large-capacity communications bureaus in each settlement zone, covering each department in the region. When the Communications Bureau is an end/convergence Board (with DTM/dl) all the communications bureaus in the whole network are connected to one network. When the two communications bureaus in a certain area are pure communications bureaus, they do not need to be connected.

3. Briefly describe network organizations suitable for medium-sized cities

The full coverage structure of the Bureau is adopted. 2 ~ 3. The Bureau covers all the terminals of the network. The Bureau is generally located in the central city of the Region network and uses a mesh network structure between the two networks.

4. Briefly describe the network organization suitable for the small network

The first-level (no settlement Bureau) mesh network structure is adopted.

5. Briefly describe the connection relationship between the signaling network and the telephone network according to the telephone network level structure stipulated by the new national standard.

HSTP-DC1, LSTP-DC2, DTM, DL, in DC1 and DC2, LSTP-DC1.

6. Briefly describe the number of phone connections and the limit of the number of transfer segments

According to the relationship between the long-distance network and the domestic network stipulated by the new national standard, in the national long-distance telephone communication, the maximum number of connection circuit segments between the two sides is 5, and the maximum number of connection switching centers is 6.

7. Briefly describe the access path type of the ISDN user at the network interface (only the name and speed are required)
The 'Access path' at the ISDN User's network interface indicates the information load capability of the interface.

▲B path: it has a scheduled 64 kbit/s path, which is used to transmit a wide range of user information flows without transmitting the signaling information exchanged by the ISDN circuit.

▲D path: it is mainly used to transmit the signaling information exchanged by the ISDN circuit, as well as remote information and group exchange data. The D-path can have different bit rates,

▲H path: the H path has the following transmission rates:

H0 path: 384 kbit/s

H11 path: 1536 kbit/s

H12 path: 1920 kbit/s

The H-path is used to transmit various user information flows, such as high-speed fax, TV images, high-quality audio or sound Programs, high-speed data, and group exchange information. It does not transmit the signaling information exchanged by the ISDN circuit.

8. Briefly describe the meaning of the "T", "S", and "R" interfaces in the ISDN User-Network Interface

"T": the demarcation points between users and networks

"S": the inbound interface of a single ISDN Terminal

"R": Provides all non-ISDN standard terminal inbound Interfaces

9. Briefly describe the types and functions of ISDN User-network interfaces and terminal Devices

Nt1: User Transmission Line terminal device, equivalent to the physical layer.

Nt2: includes physical layer functions and high-level business functions. It is generally used between nt1 and terminals.

TE1: ISDN standard terminal

TE2: Non-ISDN standard terminal

Ta: Standard Interface for connecting TE2 to ISDN

10. briefly draw the hierarchical pattern of SDH Transmission Network

11. What is the TCP/IP layered model?

Application Layer: provides users with a set of common applications

Transport Layer: Provides communication between applications

Inter-network layer: responsible for communication between adjacent computers

Network Interface

Hardware: responsible for receiving and sending IP Datagram