Slow speed???

From a quality-of-service perspective, the home Network service is largely dependent on bandwidth, assuming that other factors are not considered. Although bandwidth is important for Web content users, it is not the only important metric. As we all know, the high-bandwidth connections sold in the market are not really the transmission speed, they are only the maximum speed, is only a selling point. Just say it: don't expect to reach the speed of your ads.

Let's have a look at something ... TCP or Transmission Control protocol, is the network protocol that your browser uses to connect to a site, and is the basis for how the data is transmitted through the "pipe". TCP networks are packet-based, which means that the use of TCP networks requires the data to be chunked to be sent.

Each packet has a certain amount of protocol overhead. Such overhead affects the actual payload of the bandwidth (user content) rather than the protocol itself. And, in general, this overhead is around 15%, so no matter what service you have, the 15% overhead is unavoidable.

But what else, besides bandwidth, can affect the quality and speed of network links, and will not be mentioned by the bandwidth provider?

• Is the symmetric upload and download speed the same

• delay The well-known "Round Trip" (RTT)

• Reliability is what we call "packet loss."

High-quality networks like very many commercial-grade networks are symmetrical, with the lowest possible latency and 0 packet loss rates. The Home Network service is by no means symmetrical-its upload speed is only a small part of the download speed, high latency, and occasionally some degree of packet loss.

Symmetry of

First, why is symmetry very important? Do you remember the TCP protocol overhead mentioned earlier? TCP is a packet-based transport protocol and is a two-way communication. In order to ensure the reliable transmission of the packet flow, the connecting two parties must keep the session continuously. Therefore, the upload needs to occupy a certain upstream bandwidth. At the same time, it is interesting to assume that the download speed will also be affected if the upload channel is limited for whatever reason. The more unbalanced the upload and download speed, the more obvious the phenomenon is. Although low-cost home networks are very slow to upload, they can be as fast as they are for casual browser web pages, e-mails, and many typical online activities. But when you upload a large file or a seed provider, your upload operation can significantly affect the download speed.

Delay

Latency refers to the time it takes for a packet to reach your machine from the server you are connected to. To some extent, this is related to your distance from the server. The backbone of the internet is made up of fibers, so packets are basically transmitted at the speed of light (186,000 mph). This means that packets from Louisville to Europe take longer than Chicago, so to some extent this is a simple physical problem. However, there are several potential problems in this.

On the web, the speed slows down every time a packet passes through a mechanical device (switch and router). A typical network connection may require 10-12 "hops", and each "hop" represents a router, so the fewer hops, the lower the latency. In other words, what you really need is to reach the Internet backbone with a few "hops" that may be less. Good point-to-point network arrangement can pray for the role, at the same time, a good business-level network can also play a very important role. Here I do a high-speed comparison of my home network and work network:

• The number of "hops" from Uverse network to google.com: 13

• Twtelecom the number of "hops" from the commercial-level network to google.com: 7

That's quite an impact. In addition, the WebProject will tell you that when you access Web content in a network environment above 5M, the latency factor is more restrictive than bandwidth. And you can't reduce latency by adding bandwidth, which must be achieved by increasing your expensive infrastructure and arranging for a more reasonable peer-to-peer network-all at an expensive price. Let's take a look at the latency of the above two network environments:

• Uverse Network to google.com roundtrip time (RTT): 38 ms

• Twtelecom Business-level network to google.com round trip Time (RTT): 9.5 ms

It's quite an impact again. Mobile network is also matter, 4G network latency of more than 100 milliseconds, 3G network latency of more than 300 milliseconds.

Another complex problem is that when routers are blocked, which is overloaded, the amount of work to the router is slow, and this is a reason for the network delay, which is often seen in low-cost home networks.

Reliability

Finally, we say reliability, which is usually measured by "packet loss". When a router is overloaded with pressure and its processing speed is slower, it will randomly discard some packets at a time when it can no longer process many other data. These discarded packets are basically disappearing from the transport stream, and this must also be re-transmitted. This is a bad situation and we are able to test the loss of packets by pinging. Even if a small amount of packet loss can lead to a serious connection speed drop, the packet loss is more likely to occur on low-cost devices.

These concepts are not intended primarily for the general consumer, and most consumers do not need to know these details, mainly for the WebProject and other Internet business experts to master these concepts. Perhaps your clients often ask you to help why "my internet is not working" or "My site is very slow", assuming you can analyze these issues by descriptive narrative or take your customers to solve these problems, Then you will provide your customers with a very good service and let your customers know that your major is very valuable.

1. This paper is translated by the Program Ape Architecture

2. This article is translated from Ping me! It Isn ' t Just about Bandwidth

3. Reprint Please be sure to indicate this article from : Program Ape Architecture (No.:archleaner )

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Slow speed???