Shulou(Shulou.com)11/24 Report--

Original title: "do you know what a router is?" "

In the early morning of the Tang Dynasty, a fast horse galloped down the Imperial Avenue, an emergency of eight hundred miles. The war ahead is tight, and information on the war situation urgently needs to be sent to the capital. On the way, we have to change people and horses at every post station. We can travel 800 miles a day without a moment of delay. Even so, it would take several days for the emperor to get the information, and I do not know how many horses were tired to death during the journey.

In the 19th century, with the invention of Telegraph, telephone and fax, the efficiency of information transmission has been greatly improved, but how to transmit large-capacity data in real time is still a difficult problem. It was not until the birth of Internet in the 1990s that large-capacity data information could be transmitted in real time through the network. In Internet, there is a kind of device that silently undertakes the important task of data information forwarding, which is the protagonist we are going to talk about today-the router.

A router is a hardware device that connects two or more networks and acts as a gateway between networks. It determines how to transmit by reading the IP address in each packet. One function of a router is to connect different networks, and the other is to choose the optimal route for information transmission.

It is estimated that the concept is still too abstract, so let's start from the familiar speed of the Internet and take a look at the development and changes of routers in the network era.

Router in Modem era

In 1994, China connected to Internet with full function through a 64K international dedicated line. From then on, it was officially recognized as a country with full function Internet, and the Internet era in China began. At first, the Internet was mainly used by universities and research institutes as a scientific research tool for academic discussion. With the rise of portals such as Sina, Sohu and NetEase, more and more ordinary people use portals to visit Internet. At that time, most netizens used modems (Modem, also known as "cats") to dial up the Internet through telephone lines.

With a squeak of cats, after waiting for a minute or two, the computer was finally connected to the Internet, and netizens began to enjoy the super "slow" speed of 56 kbps. The high cost of 6 yuan per hour makes it a luxury to surf the Internet. The posture of smart netizens to unlock the Internet is as follows: after dialing up the Internet, quickly open all the web pages you want to see, then disconnect the network, and then carefully read the contents of the web pages.

At that time, there was usually only one computer at home to surf the Internet, and we didn't need a home router, so we had no idea about routers. But in fact, there are routers in the network, only used in the operator network, we can not feel it.

The router in the operator network mainly provides 10m or 100m Ethernet interface for PSTN access, and sets up X.25 or frame Relay WAN, which plays the role of data forwarding, calculates the optimal path through routing protocols such as OSPF and BGP, and uses the longest matching and one-by-one forwarding mode to send the packet to the destination.

Router in xDSL era

After a few more years, ADSL finally appeared. ADSL can be said to be the number one in broadband access. Compared with Modem dialing, it can achieve a broadband access speed of 1 Mbps uplink and 8 Mbps downlink. It not only greatly improves the Internet speed, but also makes phone calls while surfing the Internet.

At that time, ADSL dial-up Internet access is very avant-garde, if the village who uses ADSL dial-up Internet access, absolutely be regarded as leading the trend, walking on the road, will accept the envy of others at any time. After ADSL, there are more dial-up access methods based on DSL technology, such as ADSL2, ADSL2+, VDSL, VDSL + and so on, which are collectively referred to as xDSL (Digital subscriber Line, Digital Subscriber Line).

XDSL uses signal processing technology to add or obtain more digital data to analog lines to obtain high transmission rates (the theoretical value can reach 52 Mbps). With the development of the network, there is no pressure to pick up a netizen at home and watch a video. What improvements have been made to the routers in the operator's network behind the fast forwarding of data?

At this time, the router is also updated, and the access side interface is upgraded from 10-megabit or 100-megabit Ethernet interface to Gigabit Ethernet interface, so that the network bandwidth is upgraded to Gigabit Ethernet accordingly. At the same time, the router has been upgraded from X.25 or frame Relay to ATM. ATM is a cell-based packet switching technology, which uses fixed-length labels and only needs to maintain a much smaller label table than the routing table. compared with IP routing, the forwarding performance is greatly improved. The wide area network bandwidth has also been greatly improved, up to 622 Mbps, which can satisfy the Internet experience of most netizens.

Router in PON era

What really makes netizens feel at the peak of their lives is the current era of optical fiber access (PON for short). Compared with xDSL,PON network, the highest gigabit network access speed can be achieved. High-definition video and online games are all pressure-free, and the ultra-high Internet speed makes you feel great. On a hot summer day, air conditioners, Wi-Fi and watermelons can enjoy a pleasant life.

When it comes to Wi-Fi, we have to say that almost every home has a wireless router. Now that every family has multiple devices (computers, mobile phones, PAD, etc.) that need to surf the Internet, home wireless routers are naturally indispensable. In fact, if the data is to be transmitted over the wide area network, there must be carrier-grade routers used by the operators we mentioned earlier.

Wireless router is like combining wireless AP and broadband router into one. It not only has the wireless coverage function of wireless AP, but also can realize all the functions of broadband router, realize Internet connection sharing in home network, and realize wireless shared access based on xDSL, PON network or community broadband access.

Wireless router integrates router function, firewall function, bandwidth management function, broadband Ethernet WAN interface, built-in multiple 10/100/1000Mbps interfaces and 2.4GHz or 5GHz wireless band, which provides both wired and wireless access, which can be used not only in home, but also in office, enterprise and other occasions.

If we say that wireless routers are famous martial arts masters, telecom-grade routers are hidden "floor-sweeping monks". They live in major telecommunications computer rooms, and they are rarely seen except for professionals who occasionally see their true face. Faced with the demand of mass data fast forwarding, telecom-grade routers keep pace with the times, and their functions and performance are greatly improved.

Functionally, routers begin to support MPLS on a large scale, which overcomes the limitations of high cost and limited bandwidth of ATM in WAN. MPLS maps IP addresses to simple tags with fixed length independent of layer 2 and layer 3 protocols. When data is forwarded, IP packets are analyzed only at the edge of the network, rather than at each 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 and provide high performance similar to ATM technology while maintaining the simplicity of IP technology. There is no bandwidth limit for MPLS, and the single-port bandwidth capacity of WAN has been enhanced to 100Gbps.

In the future, it is expected to comply with the development of 5G, big video / VR / AR, mobile Internet, intelligent Internet of things and cloud computing, routers will also continue to upgrade, high-capacity, high-performance, full-service router products, cluster routers, virtual routers and other products emerge in endlessly. Larger capacity, higher performance, more flexible operation and maintenance, routers, the future can be expected!

The abbreviations involved in the article:

ADSL (Asymmetric Digital Subscriber Line, asymmetric Digital subscriber Line)

AP (Access Point, access point)

AR (Augmented Reality, augmented reality)

ATM (Asynchronous Transfer Mode, asynchronous transfer mode)

BGP (Border Gateway Protocol, Border Gateway Protocol)

BRAS (Broadband Remote Access Server, Broadband remote access Server)

DSL (Digital Subscriber Line, digital subscriber line)

MPLS (Multi-Protocol Label Switching, Multiprotocol label switching)

OLT (Optical Line Terminal, Optical Line Terminal)

ONU (Optical Network Unit, Optical Network Unit)

OSPF (Open Shortest Path First, Open shortest path first)

PAD (Portable Android Device, tablet)

PON (Passive Optical Network, passive optical network)

PSTN (Public Switched Telephone Network, public switched telephone network)

RADIUS (Remote Authentication Dial In User Service, remote user dial-up authentication service)

VDSL (Very High Speed Digital Subscriber Line, very high speed digital subscriber line)

VR (Virtual Reality, virtual reality)

WAN (Wide Area Network, WAN)

This article comes from the official account of Wechat: ZTE documents (ID:ztedoc)

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