Your Requirements

[pcsoft]

تشکر از دوستان بابت کمکشون.
ببخشید جسارت می کنم به نظرتون Sublayers نمی گه؟(به جای Suppliers)

[Smartie7]

Welcome, this video examines the most common LAN technology used today, Ethernet. Since its inception in 1970s, Ethernet has involved to meet the increase demand for high speed LANs of today. The continued popularity of Ethernet is due to its simplicity, reliability and low cost of installation and upgrade. Ethernet has responsibility at the lower two layers of the OSI model. The data link and physical layers, at the physical layer Ethernet involves signals and bit streams that travel along the media between communication devices, playing a key role in connecting all end devices that operate on a local area network. Ethernet divides the data link layer into two sub-layers: logical link control and media access control. At this layer Ethernet is only implemented on the Mac sub-layer. Let's review the functions of the logical link control sub-layer. The LLC's primarily responsibility is to communicate with the upper levels of the OSI stack by handling the communications between software and hardware. The LLC (Logical Link Control) sub-layer takes network layer packets from layer 3, identifies the protocol and then encapsulate the packet with control information, thus creating a layer to frame and sends it to the Mac sub-layer. An important feature of the LLC sub-layer is that it is implemented in software and thus independent a physical equipment, increasing Ethernet's capability to be compatible with many different types of media. Actually LLC processes as a frame it sends that frame to the lower data link sub-layer called the media access control sub-layer. This sub-layer has two primary responsibilities: getting data on and off the media and data encapsulation. To understand how data is placed on and removed from the media we must first understand that Ethernet is a multiaccess bus, meaning that all devices on a network share the same medium, as illustrated in this video. Because of the potential for congestion and to avoid collisions, the Mac sub-layer must dictate when descend and receive data. Ethernet uses a method called carrier sense mutiple access with collision detection or CSMA/CD to do this. This method performs, as its name implies, because it senses when the network is being used and waits until the network is not in use, before sending a frame. This method reduces the chance of collisions of frames on the network, as there is only one frame on the network at a time. If the collision does occur a jam signal is sent and each device calculates a back-off algorithm before returning to the listening before transmitting mode and attempting to transmit again. The second function of the Mac sub-layer is to encapsulate data. When encapsulating data the Mac layer adds header and trailer fields around the layer 3-data packet to create an Ethernet frame. The frame is the PDU at layer two. The beginning of the frame, the preamble and starts the frame delimiter are fields used for synchronization between sending and receiving devices, essentially the first 8 bytes of this frame is used to alert the receiving devices that data is following. The destination address and source address fields are used to identify the physical address of the destination and source devices, both of which are represented with 6-byte numbers. The length field is used to indicate the exact length of the frame's data field. This number is represented with 2 bytes and is used later in calculating the frame check sequence to ensure that the message was received properly. The largest field is the data field and contains the encapsulated data packet from layer 3. This field can range from 46 to 50 hundred bytes depending on the size of the packet received from layer 3. The last field is the frame check sequence field represented in 4 bytes. This field is used to detect errors. A destination host calculates a frame check sequence for the frame and compares it to the frame check sequence sent in the frame by the source device. If the calculations match, no error has occurred and the message is a success. Calculations that do not match are indication that data has changed, therefore the frame is dropped. The frame check sequence is a useful tool provided by Ethernet to ensure accurate transmission of methods across the physical media. As you've seen, the Mac sub-layer is responsible for many crucial operations when sending and receiving data through the physical medium. Let's look at how the assignment of the physical address also called Mac address to layer 2 frames occurs. Unlike IP addresses that are assigned by the network administrators, Mac addresses are permanent and unique to every device. No two Mac addresses are the same. And IEEE standard ensures a unique physical address for every Ethernet device. The rules require venders that sell Ethernet devices to register with the IEEE when the vender registers they are assigned a unique identifying number known as an OUI. IEEE requires the vender to follow two simple rules: First that all Mac addresses assigned to the NIC (Network Interface Card) or other Ethernet device must include that vender's OUI as the first three bytes. For this example the vender of CISCO. Second, all Mac addresses must be assigned a unique value or serial number in the last 3 bytes. You've seen how layer 2 Ethernet functions. Let's overview the physical standards. Ethernet is covered by IEEE AD2.3 standards.

یه دقیقه آخرش رو دیگه خسته شدم : دی

[pcsoft]

تشکر فراوان از دوست عزیزمون جناب smartie_7
اون یک دقیقه آخر رو هم سروران زحمتشو می کشن(حالا کی می خواد این همه رو ترجمه کنه..)
از همه دوستان بخاطر اینکه وقت گرانبها شون رو گذاشتن ممنونم.

[amir169]

ﻟﯿﻨﮏ ﺩﺍﻧﻠﻮﺩ ﮐﺘﺎﺏ workbook1 ﺑﺮﺍﯼ
ﺳﺮﯾﺎﻝ ﺁﻣﻮﺯﺵ ﺯﺑﺎﻥ @extr‏ ﻧﺴﺨﻪ
ﺍﻧﮕﻠﯿﺴﯽ ﻟﻄﻔﺎ ﺍﮔﻪ ﮐﺴﯽ ﺑﯿﺸﺘﺮ ﺍﺯ ﺍﯾﻦ
ﺭﻭ ﺩﺍﺭﻩ ﺑﮕﻪ ﻣﺜﻼ workbook2 ﯾﺎ
ﺯﯾﺮﻧﻮﯾسش

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[pcsoft]

تشکر فراوان از دوست عزیزمون جناب smartie_7
اون یک دقیقه آخر رو هم سروران زحمتشو می کشن(حالا کی می خواد این همه رو ترجمه کنه..)
از همه دوستان بخاطر اینکه وقت گرانبها شون رو گذاشتن ممنونم.

سلام
لطفا اون یه دقیقه رو متنشو لطفا بنویسید.(از دقیقه 5:35)
تشکر

[neshat22]

سلام
خیلی عالی بود .ممنون

[zardaki]

با سلام

من می خواستم زیان انگلیسی رو یاد بگیرم البته فرصت کلاس رفتن رو ندارم، می خواستم بدونم بهترین کاری که می تونم انجام بدم چیه تا انگلیسی رو یاد بگیرم اگر بسته یادگیری یا روش خاصی مد نظر دوستان لطفا پیشنها بدن با تشکر

[zohre googoooli]

kesi midune ba 330 mishe ghabul shod ya na?
age are, koja ghabul mishe?
(zarfiyete ruzaneye emsal 305 nafar , zarfiyate shabaneye emsal 126 nafar shode)

[helplab]

سلام
می خواستم جعبه لایتنر برای موبایل تهیه کنم اگر دوستان در مورد انتخاب بهترین کمک کنند ممنون می شم

من فقط تونستم همین چند تا را پیدا کنم اگر دوستان نرم افزار مخصوص موبایل دیگری سراغ دارند لطف کنند معرفی کنند.

در ضمن بزرگان اگر امکان داره دلایل برتری انتخاب خودشون را بیان کنند ممنون می شم.


ماندگار

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پایش

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پاکر(رایگان)

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[pro_translator]

سلام دوست عزیز... این نظر دوستمون seymour هستش:

اصلا توصیه نمی‌شه... موبایل چیه؟ ... اگه می‌خوای از صفر شروع کنی باید با تمرکز درس بخونی... با صفحه بزرگ... کتاب ...ورق ...

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ولی اگه برای مرور بیشتر می‌خوای باید ببینی با کدوم راحت‌تری...