For beginners, what equipment are needed for access network, backbone network, and core network, and how are signals transmitted?


 

As a beginner, it is very important to understand the hierarchical structure and equipment composition of the communication network. Below I will sort out the key equipment and signal transmission process of the access network, backbone network, and core network in an easy-to-understand way, and attach a schematic diagram to help you understand.

1. Network layered architecture

A typical communication network is divided into three layers (similar to the express delivery system):

A. Access network (last mile) → equivalent to the courier delivering the goods to your door

B. Backbone network (inter-city highway) → equivalent to inter-provincial highway

C. Core network (central dispatch center) → equivalent to the national logistics dispatch center

2. Key equipment and signal transmission at each layer

(1) Access Network

Function: Connect end users (mobile phones/computers) to the operator network.

Typical equipment:

— Wireless side:

。Mobile phones/IoT terminals → Connect via radio waves

。Base stations (4G/5G): including BBU (baseband processing unit), RRU (radio frequency unit), antenna

— Wired side:

。Home gateway (optical modem/ONU): used for fiber to the home (FTTH)

。DSLAM (for ADSL broadband)

。OLT (optical line terminal): manages fiber access for multiple homes

Signal transmission:

Mobile phone → radio wave → base station antenna → RRU → BBU → optical fiber transmission.

Home broadband → optical fiber/copper cable → ONU/optical modem → OLT → optical fiber transmission.

(2) Backbone Network

Function: long-distance high-speed data transmission, connecting networks in different cities

Key equipment:

。Router: high-end core router (such as Huawei NE5000E, Cisco CRS)

。Fiber optic transmission system:

。DWDM equipment: multiplex multiple signals into one optical fiber (similar to a multi-lane highway)

。OTN equipment: provides large-capacity optical transmission channels

。Relay amplifier: long-distance optical fiber signal regeneration

Signal transmission:

Access network equipment → aggregation switch → backbone router → DWDM/OTN → inter-city optical fiber → next-hop router

(3) Core Network

Function: Network-wide control center, responsible for user management and service scheduling

Key equipment:

。4G core network (EPC):

。MME (mobile management entity)

。S-GW/P-GW (service gateway/packet gateway)

。HSS (user database)

。5G core network (5GC):

。AMF (access management function)

。SMF (session management function)

。UPF (user plane function)

。General equipment:

。Cloud server (NFV virtualization deployment)

。Firewall/load balancer

Signal transmission:

Backbone network data → core router → divert control signaling and user data

Control signaling → MME/AMF (manage user access).

User data → S-GW/UPF (forward to the Internet or other networks).

3. End-to-end signal transmission example (taking mobile phone access to website as an example)

A. Mobile phone sends request:

Mobile phone → Base station (wireless signal) → BBU → Fiber transmission to access network aggregation point

B. Access network to backbone network:

Base station controller → aggregation router → Enter backbone network through OTN/DWDM

C. Transmission across backbone network:

Jumping through multiple backbone routers (may span multiple cities)

D. Core network processing:

。Backbone network → Core network gateway (P-GW/UPF) → Connect to the Internet.

。Core network simultaneously completes user authentication, billing, and traffic management.

E. Reaching the target server:

Arriving at the website server through the Internet, data returns along the original path

4. Equipment manufacturer reference

。Access network: Huawei, ZTE, Ericsson, Nokia

。Backbone network: Cisco, Juniper, Huawei (high-end routers), Ciena (optical transmission)

。Core network: Huawei, Ericsson, Nokia (traditional equipment vendors), AWS/Microsoft (cloud core network)

5. Summary of key technologies

Network layer Transmission technology Typical protocols

Access network Optical fiber/radio wave GPON, 5G NR

Backbone network Optical fiber DWDM/OTN BGP, MPLS

Core network IP/cloud virtual network HTTP/2, SIP

6. Learning suggestions

。Beginner’s experiment: Use Wireshark to capture packets and observe home broadband data flow.

。Simulation tool: GNS3 simulates router networking.

。Industry certification: CCNA (Network Basics), 5G-related certification (such as Huawei HCIA-5G).

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