ccna 200-301 network simulator tools today discount

ccna 200-301 network simulator tools today discount.Figure 2-3-6 Viewing an Application's Port NumberThe TCP and UDP protocols are described in more detail later in this book in the TCP/IP Reference Model.2.3.5 Session LayerThe SessionLayer allows users on different machines to establish a session relationship with each other, and one of the services provided by the SessionLayer is management of conversation control. The session layer allows messages to be transmitted in both directions at the same time, or only in one direction at any given moment. If the latter is the case, similar to half-duplex mode on a physical channel, the session layer will record which party's turn is due at that moment. One service related to conversation control is token management, and it is important that some protocols guarantee that both parties cannot perform the same operation at the same time. To manage these activities, the session layer provides tokens, which can be moved between the two sides of the session, and only the side holding the token can perform certain critical operations. Another session layer service is synchronization; think of the problems that would arise if a two-hour file transfer were to take place between two machines on a network that averages one major failure per hour. Each time the transfer fails halfway through, the file has to be not retransmitted. When the network has another big failure, it may be halfway through again. To solve this problem, the session layer provides a way to insert synchronization points into the data. After each network failure, only the data after the last synchronization point is retransmitted.The session layer is barely covered in the CCNA exam.2.3.6 Representation layer*. *.The Representation Layer performs certain specific functions for which one would often like to find a general solution without having to implement it by each user himself. It is worth noting that the layers below the surface layer are only concerned with the reliable transmission of bits from the source host to the target host, whereas the representation layer is concerned with the syntax and semantics of the information being transmitted. A typical example of a representation layer service is the encoding of data in a standard method chosen by consensus.Computers on a network may use different data representations, so data format conversions are required for data transmission. For example, different codes are commonly used on different machines to represent strings (ASCH and EBCDIC), integer numbers (binary inverse or complement), and different byte orders of machine words, etc. In order to allow computers with different data representations to communicate with each other and exchange data, we use abstract data structures to represent the transmitted data during communication, while still using the respective standard codes inside the machines. Managing these abstract data structures and converting the machine's internal encoding to a transmission syntax suitable for online transmission on the sender side, and doing the opposite on the receiver side, etc., is done by the representation layer.In addition, the representation layer is involved in data compression and decompression, data encryption and decryption, etc.2.3.7 Application Layer***