As economic globalization and digital transformation accelerate, enterprises keep expanding their scales. More and more branches are located in different regions, with each branch network being considered as a local area network(LAN). The headquarters and branches need to cross geographical locations to communicate with each other. To better carry out services, an enterprise needs to connect these geographically dispersed branches through a wide area network(WAN). There are many WAN and LAN device like ZTE/HUAWEI optical modem and router, such as GPON
ONT HG8321V,
K662C.
The development of the WAN technologies is accompanied by the continuously increased bandwidth. In the early stage, X.25 provides only the bandwidth of 64 kbit/s. Later, the digital data network(DDN) and Frame Relay(FR) increased the bandwidth to 2 Mbit/s. Synchronous digital hierarchy(SDH) and asynchronous transfer mode(ATM) further increased the bandwidth to 10Gbit/s. Now, the current IP-based WANs provide 10 Gbit/s or even higher bandwidth.
What is WAN?
WAN is short for a wide area network, it is a network that connects LANs in different areas. A WAN generally covers tens of kilometers to thousands of kilometers. It can connect multiple regions, cities, and countries, or provide long-distance communication across several continents, forming an international remote network.
WAN network and LAN network
Figure 1: WAN network and LAN network
What is the main difference between the LAN and WAN?
Firstly, compared with the LAN, which provides high bandwidth but supports only a short transmission distance, WAN provides a low bandwidth but a long transmission distance.
Secondly, LAN usually implements the switches, while the WAN implement mostly routers.
Besides, LAN and WAN usually use different protocols or technologies only at the physical layer and data link layer.
At last, the Internet is only a type of WAN. Small enterprises use the Internet as the WAN connection.
LAN and WAN technologies
Figure 2: LAN and WAN technologies
WAN device roles
There are three basic roles of WAN devices: CE(customer edge), PE(provider edge), and P(provider).
CE: a device located at the customer premises and connected to one or more PEs for user access.
PE: a service provider's important edge device that is connected to both a CE and a P.
P: a service provider's device that is not connected to any CE.
WAN device roles
Figure 3: WAN device roles
Application of early WAN technologies
The early WAN technologies perform different Layer 2 encapsulation at the data link layer for different types of physical links. PPP, HDLC, and FR are commonly used between CEs and PEs to implement long-distance transmission of user access packets over a WAN. ATM is commonly used on ISP backbone networks for high-speed forwarding.
Application of early WAN technologies
Figure 4: Application of early WAN technologies