It is an outline of the ATM.

Well, I think that I do the problem of the ATM today. "Outline of the ATM" and the part that is only announcing and should suppressed by studying the ATM are published though it is thought that it only has to be able to read easily because this problem is "Fill-in-the-blank question". It first has in mind and it puts around here when not good at problem of the ATM. Then, today's material is [kochira] ↓↓.



- Outline of ATM



The cell used by the ATM is composed of 【53 bytes 】 that adds the header that contains routing information etc. by user information on the voice, the image, and data, etc.
- The ATM cell is composed of 【53 bytes 】 adding the header to user information.



In each cell header of the ATM, 【VCI】 that identifies a virtual channel as a connection identifier necessary to send it to the address until sending it and a virtual passing are identified. There is VPI, and the cell is turned to the address based on this information and the ATM switch is forwarded. At this time, to appear on the market, to seem to select [sen], and to advance, the ATM switch is said by the cell 【 self routing switch 】 about the address.

- 【VCI】 = virtual channel is identified.
- VPI = virtual passing is identified.
- 【 self routing switch 】 = seems to select the output line of the address by the cell and to advance.



There is a method of assuming a virtual channel to be to be remain set for a long term by the method and the contract, etc. to set to the setting method of a virtual channel only to communicate, and to liberate a virtual channel with the end of the communication. The virtual channel set by a latter method is called 【PVC】.
- Method of setting only SVC = to communicate, and liberating virtual channel with end of communication
- 【PVC】 Method of assuming virtual channel to be to be remain set for a long term by = contract etc.


Sleep. Outline really ?Because the part of the deficit becomes a really basic part to understand the ATM by right sentences, it neatly has in mind and it puts it. Coco is a liver of the ATM It was sentences explained almost bringing the ATM together. Then, because the outline was published a little more a little while ago, the problem of the ATM cell is done this time. Then, the following material is [kochira] ↓↓.



- Kind of ATM cell



To have continuously to spread the ATM cell over the payload of the SDH frame when the ATM cell is forwarded on the SDH network, an empty cell is inserted and forwarded between cells with effective information.

These sentences are correct.
- Because the payload is not integral multiples compared with 53 bytes of the size of the cell of the ATM, the last ATM cell on the frame might be accommodated across the following frame though the mapping is done by the payload of a virtual container of SDH as for the cell style to which the speed adjustment is done.
- An empty cell is inserted to put the speed of the ATM cell (speed of the valid cell) together at the transmission speed of SDH and the speed of the cell style adjusts.
- The ATM cell fully packs the package, inserts "Empty cell" in the opening part, and is doing the carrier of trailer (SDH) to SDH without the space. (padding)
- [Shitete], address VPI of the specialized form, and VCI become special like any one's neatly understanding "I am an empty cell" because it is not good this empty cell, too.



It is said by the ATM cell that doesn't contain the mistake in the header the valid cell excluding an empty cell.

These sentences are correct.
- The cell is . because it is errorless in the header excluding an empty cell (real cell) ..effective... ｡｡



It is said by the ATM cell to which the mistake is detected in the header, and it is corrected the invalid cell excluding an empty cell.

These sentences are wrong.
- This cell is up to . because it enacted the cell mistake ..effective.. though it might have been found to mistake it to the header excluding an empty cell (real cell). ｡｡･･･ It is a Japanese problem. ｡｡



When the cell mistake received in the error correction mode is detected, it mistakes it, and if the number of bits is one bit, it corrects, and if it is two bits or more, the cell is annulled.

These sentences are correct.
- I think that it is "FEC" that has come out before. Being able to do the error correction : only by one bit (annulment any more it) though FEC is possible the error detection and correction.



The difficulty so much doesn't write, and have it in mind, please often reading though "Oh…" seems to become because it fully packed the character in a narrow table for a moment. It often reads because the part that is the most basic the first half of today and this problem in the latter half understand the ATM. Then, around here today