Rebirth of the Tech Madman

It can be said that this situation of ice and fire is a reflection of the differences in cognition between theory and practice, academics and business, on the realization principle of LAN technology.

Logically, Ethernet adopts a bus-type topology and uses - csma/cd, which is the bus contention technology of carrier sense multiple access/collision detection.

Between each node on the network, that is, computers, in the process from sending to receiving, a transmission unit will be generated, that is, a data packet-the concept of a frame.

——cs is carrier sense, which means that any computer connected to the network must listen to the network before sending a frame, and can only send it when it is confirmed to be idle.

——ma means multiple access means that multiple computers can access the network at the same time, and frames sent by one computer can also be received by multiple computers, which is similar to broadcasting.

Obviously, this kind of network usage will inevitably cause frame collisions.

Just like a two-way two-way lane, the frames of motor vehicles, non-motor vehicles, people, pets, etc. are all scrambling to get on the road, and accidents such as scratches will inevitably occur.

The collision problem cannot be cured, but it can be alleviated through some listening/sending strategies, one of which is-cd is collision detection.

It requires the computer to listen to the network while sending frames to determine if a collision has occurred.

If a collision is detected while sending data. Then perform the following collision processing operations:

first. Send special blocking information. And immediately stop sending data. The special blocking information is all 1 signals of several consecutive bytes. This is intended to strengthen the collision so that other computers can detect the collision as soon as possible.

To put it more vividly, it is broken and smashed, so that everyone can see the heavy traffic and don't go on the road.

Second, wait a random amount of time for a fixed amount of time, and send again.

At last. If there is still a collision, it will be sent using the truncated binary exponential backoff algorithm. That is, within ten times, stop random resending within twice the previous fixed time, and after ten times, stop random resending within the previous fixed time. After 16 attempts, if you still fail, give up the transmission.

This method is like a metropolis with congested traffic, and the relevant departments arrange odd and even number restrictions according to the license plate number.

Obviously, collisions during Ethernet operation will cause a certain degree of waste of resources and lack advantages in execution efficiency.

In stark contrast to this.

A 4m Token Ring network is equivalent to a 10m Ethernet data transfer rate. The data transfer rate of a 16m Token Ring network is close to that of a 100m Ethernet.

The reason why there is such an obvious gap is, of course, because the basic operating principles of each other are completely different.

Token Ring networks use tokens, which represent permissions for signaling, to avoid conflicts in the network.

The computer that gets the token is like a police car that pulls the alarm and has the exclusive lane, monopolizing the network to send data. Compared with the operation mechanism of the computers on the Ethernet that are constantly probing and looking for blocking opportunities, the data transmission rate of the network is naturally increased.

Moreover, the priority of transmission can also be set through tokens to meet high-level network resource requirements.

Theoretically, the token ring network is impeccable, but in practice, because the network cannot be reused, the utilization rate of the token ring network is low.

When a computer in the network gets the token and starts using the network, no matter how much bandwidth the computer uses, even if it only uses 1m of the 4m, other computers must wait for it to finish using the network and give up the token before they have a chance Apply for a token and use the network.

It's like a privileged car driving on a road without interruption. Even if there are eight lanes, other ordinary vehicles can only stare blankly and cannot get on the road.

Especially when the network becomes complex, the programs running in each computer are written by humans, and the faint desire to monopolize the network makes the theoretical smoothness of token circulation impossible to obtain the expected guarantee. Correspondingly, The utilization rate of network resources is not high.

Overall, Token Ring, which is similar to a planned economy, is not as dynamic as Ethernet, which is similar to a market economy.

The benefits of using the network through spontaneous coordination between computers on the Ethernet outweigh the losses caused by the collision phenomenon.

However, the correct understanding of this point is far from being popularized. Large companies such as Theoreticians and IBM are favoring token ring networks.

The famous computer scientist Jerry Saltzer, in an influential paper co-authored with others, pointed out that in theory, token ring network is superior to ethernet.

In 1964, before Ken Thompson and Dennis Ritchie developed C language, Bell Laboratories, Massachusetts Institute of Technology and General Electric jointly participated in the development of a multi- A multitasking operating system—that is, jerry saltzer was one of the leaders of the team at the time.

Therefore, jerrysaltzer's status in the arena is not low, and his views are very influential. Affected by this conclusion, many computer manufacturers either hesitate or simply decide not to use the Ethernet interface as the standard configuration of the machine.

However, the advantages of Ethernet with a simple structure in the actual use process cannot be ignored. In the original time and space, 3, which was neglected in time and space, was a blessing in disguise. It made a lot of money by selling individual Ethernet network cards, and quickly grew into a large international company, and then appeared. An almost joking statement - Ethernet is not suitable for theoretical research, but only for practical application.

However, the brilliance of 3 will have to wait a few years later, and now this company has been established for more than a year. They are lobbying other manufacturers everywhere. Embrace your own technique.

so far. Robert Metcalf, who is running around, has also made some progress, such as cooperating with, Intel, and Xerox to standardize Ethernet, launch a standard, and develop a commercial version for use.

And Tang Huan's goal is to take out the PC version with 3 and occupy the highest point in the industry first.

Because of Simeone's relationship. Tang Huan had already had some contact with Robert Metcalf earlier, so the process of this meeting and various verbal temptations can be omitted directly.

Accompanied by another man and a woman, two philosophical engineers in their 30s: David Boggs and Radia Perlman.

Since the database ebase became very popular in the market at the end of last year, especially after the sales of Xiaobawang game consoles exploded, the company under Tang Huan's name has become more attractive to high-end talents. people.

In the original time and space, David Boggs and Radia Perlman both went this year. As a result, Zheru's human resources department, who was ordered to recruit Internet talents for the 386 plan, was recruited into the company. This kind of search ability made Tang Huan amazed.

usually. Ethernet is believed to have been invented in 1973 because Robert Metcalfe wrote a memo to his boss about the potential of Ethernet.

However, according to Robert Metcalf himself, Ethernet came a few years later. That is, in 1976, Robert Metcalfe and his assistant, David Boggs, jointly published an article entitled Ethernet: Distributed Packet Switching Technology for Regional Computer Networks.

Robert Metcalfe left to found 3, and David Boggs also left, but after getting his master's degree, he continued to stay on the West Coast, planning to study for a Ph.D. at Stanford University, and then came to Zheru.

As for Radia Perlman, after graduating from the Massachusetts Institute of Technology with a master's degree in mathematics, she worked on software development for network equipment. I don't know how Zheru's human resources department fooled her and brought her from the east coast to the west coast.

Don't underestimate this point. Universities in the United States are divided into circles. What kind of university a person chooses often means his future job level and even the range of spouse selection.

In the original time and space, Radia Perlman made a lot of achievements in technology. The most important point may be that in 1983, she invented the spanning tree algorithm and developed the stp spanning tree protocol for bridges and switches. , which is of great significance to the formation of large-scale networks.

Later, Radia Perlman was dubbed the Mother of the Internet, but she reportedly didn't like the title.

Radia Perlman's work is actually to develop a basic data transmission method for the network (inter),

It is no exaggeration to say that the technicians on site are all experts in network.

However, Tang Huan didn't want to enter the technical discussion right away. He first asked about the possibility of investing in 3, because Robert Metcalf attracted a lot of venture capital when he founded the company, so that he had no right to speak Yes, there are some things that he can't decide by himself.

One of the manifestations is that the recent 3 boards of directors invited another one. As for Robert Metcalfe, he was appointed as the chairman of the company's board of directors and concurrently served as the vice president of the company's marketing and sales department, which can be regarded as a balanced power structure.

In Tang Huan's view, such operations by capitalists have their own reasons. Entrepreneurs with professional technical backgrounds may not be competent for the management of their own companies.

In the original time and space, Robert Metcalfe was finally kicked out in 1990, which was similar to the fate of the two founders of Cisco. The time was not far behind, and the two companies also entered a period of rapid growth after a brief adjustment. .

Complaining too much is useless, even if the facts are so cruel, creators need to reflect, at least Tang Huan thinks so.

Moreover, Robert Metcalfe is very active, playing the role of prophet in the network world.

He once proposed the famous Metcalfe's Law, which is comparable to Moore's Law: The value of the network is proportional to the square of the number of users connected to the network.

Various social software have verified the correctness of this statement. There is a big V account with tens of thousands of fans on Weibo. What is its value. It is obvious to all.

Of course. Robert Metcalfe's big mouth wasn't always right, and it got him ridiculed.

For example, Robert Metcalfe once predicted in 1995 that the Internet would usher in a devastating paralysis in 1996. In fact, of course, everyone is fine.

Robert Metcalfe also predicted that wireless networks would die in the mid-1990s, but the reality is that users are looking for a signal everywhere.

Robert Metcalfe didn't stop there, and made another social network bubble speech. It seems that the companies involved are still making a lot of money.

It can be seen that the so-called pioneers have a mythical aura imposed by others. At least when Tang Huan was dealing with Robert Metcalfe, he felt that the other party was normal.

He could tell, for example, that Robert Metcalfe would love to see him invest in 3, because Robert Metcalfe wanted to have another partner on the company's board of directors.

Even so, Robert Metcalfe, who has no decision-making power, showed embarrassment, Don't look at me as the chairman of the board of directors. But I was manipulated by those guys, and I discussed it twice. It didn't matter. .”

The situation is different now. We have officially launched the second-generation Fangyuan computer, which can be called the first 16-bit personal computer with practical value. This card's support for Ethernet technology is not enough for those people. Are you interested?

Even so, the board of directors will not agree to sell 20% of the shares, otherwise, the existing power structure will change. Robert Metcalfe spread his hands helplessly, I suggest you lower the target, and use the more powerful sales performance of the second-generation Fangyuan computer as evidence of persuasion.”

Tang Huan rubbed the space between his brows, and had to accept the second best.

As a mechanical product, hard disk, no matter how big its capacity becomes or how fast its speed becomes, it cannot get rid of its position at the end of the industrial chain.

But the Internet is different. Those venture capitals are all world-class in intelligence. Naturally, they have long been concerned about it, and they are unwilling to give up possible future benefits in the early stages of development.

Seeing that Tang Huan was doing good, Robert Metcalfe breathed a sigh of relief, and joked, You'd better go to 3 officially, and let the members of the board of directors see you, who has made hundreds of millions from the personal computer industry. Wealthy rich man, shock some of these guys.

It seems that Robert Metcalfe, who is a little bit angry, hopes that he can support him.

Tang Huan smiled and nodded, Let's not talk about this, let's talk about the realization of Ethernet on the second-generation Fangyuan computer. Zheru mainly works on software. Your network card and driver, the sooner you get it Come out, the more the industry will know the advantages of Ethernet.

To be honest, Zheru's enthusiasm for LAN is beyond my expectation. Can you tell me about any heavyweight applications you have? Robert Metcalf asked tentatively.

Tang Huan glanced at Simeone appreciatively. Don't look at Simeone who has a lot of friendship with Robert Metcalfe, but he is unambiguous in keeping business secrets.

We are developing a major function upgrade of the database ebase, which is to support the client-server structure. Tang Huanliang pointed out Zheru's dry goods.

Can I have a look at the demonstration? Robert Metcalf, whose eyes lit up, suddenly became very interested.

Structure - the c/s structure is also called - that is, the master-slave architecture, and the characteristics of this technology can be seen only from the literal meaning.

The c/s structure is not a new thing, it has been studied as early as the 1970s, so Robert Metcalfe is no stranger.

Of course, we have already built a simulation platform. Tang Huan asked Simeone to prepare for the demonstration, while he continued to discuss the cooperation with Robert Metcalfe on Ethernet.

Glancing at David Boggs and Radia Perlman, Robert Metcalfe said with emotion, Don, you have a long-term vision in terms of technology. It is only a few months later than Zheru, but it is much worse in terms of structure.

What you see is only the surface. I'm walking on thin ice. Tang Huan shook his head and loosened his tie. When IBM's personal computer is launched, I don't know how many companies and brands will be eliminated.

Don't worry, it is basically impossible for 3 to enter the ibm camp. We are friends in the trenches. Robert Metcalf laughed.

...

After the successful development of the Fangyuan second-generation computer, the work pressure it brought was not ordinary. Tang Huan wanted to go to Xiangjiang to relax, but he couldn't spare the time.

The executives under him were equally busy. For example, Hawkins, who had just inspected the game business in Japan, had just returned to the United States and brought a piece of news from United Artists to report to Tang Huan.

Michael Cimino, who won the Oscar for best picture and best director for a short time, directed the epic Western film Heaven's Gate costing 40 million US dollars, which was released on November 19.

So far, the audience has complained, and the box office is dismal, and it is expected to only recover about 1.5 million.

Lianmei, whose family fortune has been ruined, is panicked from top to bottom.

Even those who have made it clear that they will pledge allegiance to EA in the future are beginning to feel uneasy. Such a money-losing product won't scare EA away, right? (To be continued..)

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