cnp3-ebook/principles/reliability — Czech @ Weblate: `DLE STX` **DLE** `DLE` **STX** **DLE** `DLE` ETX** `DLE ETX`

	English	Czech	Actions
	`space` : `0100000` b
	In addition, the :term:`ASCII` table also defines several non-printable or control characters. These characters were designed to allow an application to control a printer or a terminal. These control characters include `CR` and `LF`, that are used to terminate a line, and the `BEL` character which causes the terminal to emit a sound.
	`NUL`: `0000000` b
	`BEL`: `0000111` b
	`CR` : `0001101` b
	`LF` : `0001010` b
	`DLE`: `0010000` b
	`STX`: `0000010` b
	`ETX`: `0000011` b
	Some characters are used as markers to delineate the frame boundaries. Many `character stuffing` techniques use the `DLE`, `STX` and `ETX` characters of the ASCII character set. `DLE STX` (resp. `DLE ETX`) is used to mark the beginning (end) of a frame. When transmitting a frame, the sender adds a `DLE` character after each transmitted `DLE` character. This ensures that none of the markers can appear inside the transmitted frame. The receiver detects the frame boundaries and removes the second `DLE` when it receives two consecutive `DLE` characters. For example, to transmit frame `1 2 3 DLE STX 4`, a sender will first send `DLE STX` as a marker, followed by `1 2 3 DLE`. Then, the sender transmits an additional `DLE` character followed by `STX 4` and the `DLE ETX` marker.
	1 2 3 4
	`DLE STX` 1 2 3 4 `DLE ETX`
	1 2 3 DLE STX 4
	`DLE STX` 1 2 3 DLE `DLE` STX `4` `DLE ETX`
	DLE STX DLE ETX
	`DLE STX` DLE `DLE` STX DLE `DLE` ETX** `DLE ETX`
	Recovering from transmission errors
	In this section, we develop a reliable datalink protocol running above the physical layer service. To design this protocol, we first assume that the physical layer provides a perfect service. We will then develop solutions to recover from the transmission errors.
	The datalink layer is designed to send and receive frames on behalf of a user. We model these interactions by using the `DATA.req` and `DATA.ind` primitives. However, to simplify the presentation and to avoid confusion between a `DATA.req` primitive issued by the user of the datalink layer entity, and a `DATA.req` issued by the datalink layer entity itself, we will use the following terminology :
	the interactions between the user and the datalink layer entity are represented by using the classical `DATA.req` and the `DATA.ind` primitives
	the interactions between the datalink layer entity and the framing sub-layer are represented by using `send` instead of `DATA.req` and `recvd` instead of `DATA.ind`
	To solve this problem, a reliable protocol must include a feedback mechanism that allows the receiver to inform the sender that it has processed a frame and that another one can be sent. This feedback is required even though there are no transmission errors. To include such a feedback, our reliable protocol must process two types of frames :
	data frames carrying a SDU
	These two types of frames can be distinguished by dividing the frame in two parts :
	the `header` that contains one bit set to `0` in data frames and set to `1` in control frames

Loading…

None

New source string

cnp3-ebook / principles/reliability — Czech

New source string 5 years ago

Browse all component changes

Glossary

English	Czech
No related strings found in the glossary.

String information

Source string location

../../principles/reliability.rst:262

String age

5 years ago

Source string age

5 years ago

Translation file

locale/cs/LC_MESSAGES/principles/reliability.po, string 83