Advanced questions about the service type field of IP datagrams: TOS questions

The Service Type (to S) (8-bit) field includes a 3-bit priority subfield (the value can range from 000 to 111), a 4-bit To S subfield, and a 1-bit unused but must be set to S to represent the minimum latency, maximum throughput, highest reliability, and minimum cost, respectively. Only one of the 4 bits can be placed.

If all 4 bits are 0, then it means that it is a general service.

So, what you said is not satisfied with the existing numeric type, only the last digit of the 4-bit TOS (which must be 0 by default) can be modified to an unrecognized field. As for whether the router drops or ** after receiving this kind of 'special' packet, I personally feel that if the packet header verification can be calculated, it should be able to be captured.

This problem is not so complicated, if the service type TOS field of the IP packet is wrong, and it is found that it does not meet all the existing data types when the IP performs the first verification, then it will be judged that the packet is wrong and will be directly discarded.

The receiver does not send a datagram to report an error, and the IP that works at the network layer is meant to transmit the packet as much as possible. Of course, nature has its own mechanism for handling faulty packets.

TOS is often used as QoS for quality assurance during data transmission. To put it in layman's terms, the road is narrow and there are many cars, so the priority is marked for cars, some cars go first, some cars go later, and some cars are not allowed to go. Routers, like traffic police, direct traffic, and how they operate depends on a predetermined strategy.

For terminals (such as computers), the packet has already been received, so it does not care about this field.

Open both **! Then use"Lasso, magic wand, extraction under filter. "and so on.

It's better to use a lasso, upstairs says to use a magnetic lasso, if the portrait is close to the background, it is better to use the lasso directly. Make the character so big that it is circled, click the move tool, press the left mouse button to drag the character to your favorite background**, adjust the size position, use the eraser to erase the excess around the character, and make a feather on the edge to be more harmonious! Save it and you're going to craft.

The layer is overwritten, of course, you can only see one layer, simpler you can first open two **, use the "Magnetic Lasso Tool" in the left toolbar to click around the portrait, (the last point of this tool should fall on the starting point).

Finally, select the portrait in a dotted encirclement, and then select the "Move Tool" in the toolbar, and drag the portrait to another **

TOS+ is Tencent's latest strategy, it can make all connections become handy, some people commented, it will become a new fulcrum to change the hardware world, can change our world, has extraordinary significance, it will help intelligent hardware from the bottom of the system to quickly develop this disturbance, it will unite ZTE, Huawei, Didi Dache and other companies to take the lead in Bi Pa Lu to start cooperation, which will greatly facilitate our life.

Translation of the original text:

Please help us look through these sites

and report any violations of these Terms of Service. （ and report any that are against the tos.）

We will give you a small gift for your report. （we'll give you a little gift for reporting.）

tos：

English name of Token: terms of service

Chinese meaning: Terms of Service.

Extended Content:

Terms of Service Usage:

Legal Terms of Service agreements are legally binding and subject to change. The Company may enforce the Terms by denying service. Customers can enforce it by filing a lawsuit or arbitration case if they can prove that they were in fact harmed by the breach of the terms.

In the case of improper data transfer, there is a higher risk of data going astray during business changes, including mergers, divestitures, acquisitions, downsizing, etc.

Terms of Service:

User Rights and Responsibilities.

appropriate or intended use; Definition of abuse.

Privacy policy outlining the use of personal data.

Payment details, such as membership fees or subscription fees, etc.

The opt-out policy describes the account termination procedure, if any

Arbitration details the dispute resolution process and the limited right to bring a lawsuit in court.

User notice when the Terms are modified, if provided

What is TOS"The IP data header contains an 8-bit field called TOS (Service Type). This field has been a verbal part since the beginning, but it was rarely used until the recent introduction of the diff-serv. rfc 791(：

Internet Protocol, September 1981). It was later further elaborated in RFC 1349 (Type of Service in the Internet Protocol Suite, July 1992). In the early days, attempts were made to specify how it could be used to calculate individual routes through the network based on the service type specification.

The field is defined in two parts: the priority value and the TOS bit. Priority values occupy the leftmost 3 digits and are intended to provide a form of priority queue.

The bit specifies how the network balances throughput, latency, reliability, and cost. The IETF Differentiated Services Working Group has redefined the TOS field and renamed it to the "Differentiated Services" field. Fields with 6-bit DS are used as code points to select:

PHB (hop-by-hop behavior), which defines how packets of data are queued in network nodes. This topic will continue to be discussed in the topic "Differentiating Services (diff-serv)". "

"TOS" is "two." d. o .s", also an abbreviation of ".

Chinese means "super human defense".

It is a non-United Nations super-human research organization established on December 30, 2019 in Loxas, USA, including future science and technology research organizations such as superhuman modification and superhuman devices, as well as the future defense of the earth organization.

TOS is the service type mark of Layer 3 packets, which is also 3 bits, ranging from 0 to 7, which can also be used as priority markers, and the other 5 bits that actually indicate the characteristics of delay, throughput, and reliability are generally not used; Now, in order to better control the classification of data flows, DSCP (Differential Services Code Point) is used to extend the last three bits of TOS, so that the range is from 0 to 63.

This has been particularly popular recently,Called TOS,It is exclusively developed by Tencent,The full name is Tencent OS,Now it's an upgraded version,In Tencent"Connect infinite possibilities"At the press conference with the theme of April 28th,Bird letter has been upgraded to TOS+

The slogan of TOS+ is even louder, "only to pry the cracks of the hardware world". Penguin's strategy of opening up the platform for smart hardware can be said to be very successful, and its partners already have a number of well-known digital companies, including ZTE.

These are not architectural majors. It should be a symbol unique to the structure and equipment-related professions.

You have to see what kind of professional symbol you have!

WL sewage riser, FL wastewater riser, should be the equipment professional marking, tell me the nature of your drawing, otherwise it is not easy to say.

Those who have successfully applied for the internal test qualification can go down to the OS to brush,Experience this minimalist style of operating system,If you are not qualified, you can't go down now,But I believe that the official version of the firmware will be released soon after the end of the internal test

I heard that the overall style of this ROM system is very compatible, and the wallpapers and icons look clean and concise, so you can experience it yourself with patience and wait!

I heard that this system goes a lightweight design.

It looks like it's about to be open beta, so if you're interested, you can pay more attention.

Click it out, then cancel. Then disable the auto-detect updates.