The routers in the operator's network mainly provide 10M or 100M Ethernet interfaces for PSTN access, and set up an X.25 or frame relay wide area network, which is responsible for data forwarding, and calculates the optimal path through routing protocols such as OSPF and BGP. The longest match and one-by-one forwarding methods send packets to the destination.At that time, ADSL dial-up Internet access was very avant-garde. If anyone in the village used ADSL dial-up Internet access, it would definitely lead the trend. Walking on the road, they would be envied by others at any time.After ADSL, there are more dial-up Internet access methods based on DSL technology, such as ADSL2, ADSL2+, VDSL, VDSL+, etc., which are collectively referred to as xDSL (Digital Subscriber Line).At this time, the routers are also upgraded, and the access-side interface is upgraded from a 10M or 100M Ethernet interface to a Gigabit Ethernet interface, so that the network bandwidth is also upgraded to Gigabit Ethernet accordingly.At the same time, the router was upgraded to support ATM from the original only supporting X.25 or frame relay.ATM is a packet switching technology based on cells. It uses fixed-length labels and only needs to maintain a label table much smaller than the routing table. Compared with IP routing, the forwarding performance is greatly improved.The bandwidth of the WAN has also been greatly improved, reaching a maximum of 622 Mbps, which can already satisfy the Internet experience of most netizens.A wireless router is like a combination of a wireless AP and a broadband router. It not only has the wireless coverage function of the wireless AP, but also can realize all the functions of the broadband router, realize the Internet connection sharing in the home network, and realize the network based on xDSL, PON or community. Wireless shared access for broadband access.Functionally, routers began to support MPLS on a large scale, overcoming the limitations of expensive ATM and limited bandwidth in the WAN.Independent of Layer 2 and Layer 3 protocols, MPLS maps IP addresses to simple labels with a fixed length. During data forwarding, only IP packets are analyzed at the edge of the network instead of at every hop, thus saving processing time.In terms of performance, the access-side interface of the router (the interface between the router and the BRAS) has been upgraded to a 10G or 40G Ethernet interface.MPLS can combine the advantages of ATM and IP technology to provide high performance similar to ATM technology while maintaining the simplicity of IP technology.MPLS has no limit on bandwidth, and the single-port bandwidth capability of WAN has been increased to 100Gbps.ADSL (Asymmetric Digital Subscriber Line, Asymmetric Digital Subscriber Line)BRAS (Broadband Remote Access Server)OSPF (Open Shortest Path First)PAD (Portable Android Device, Tablet)PSTN (Public Switched Telephone Network)RADIUS (Remote Authentication Dial In User Service)VDSL (Very High Speed ​​Digital Subscriber Line)