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Which OSI layer uses the header information to reassemble the data segments into streams?

transport layer


Which OSI layer is responsible for adding a header that includes routing information?

The routing process occurs in the 3rd OSI layer (network layer) routing protocols use network address (IP address in TCP/IP) to chose the correct path to the destination. ps: You can also have routing protocols on other layers sometimes (application layer in p2p routing) but this is something completely different.


Difference between transport and network layer?

+network layer logical communication between hosts +transport layer: logical communication between processes ex: we have 2 house and one house have 12 room. kids in the houses send letter together. network layer: only send letter between the houses transport layer: it make sure that the letter be sent to right the room in the house.


What osi model layer do protocols manage data delivery priorities?

Network Layer


Differences between IPV4 header and IPV6 header?

Figure 1 IPv4 Header Figure 2 IPv6 Header One feature of IPv6 that immediately comes to our mind is huge address space. This refers to the fact that, among many elements shown in Figure 1 and 2, the Source Address and the Destination Address has each been expanded from 32 bits to 128 bits. If you just think in terms of pure combination of numbers, there used to be 232 possible ways to represent addresses, but now there are 2128 possible ways to represent them. However, if you compare Figures 1 and 2 again, you will realize that although IPv6 uses four times more digits to express the addresses of the source and the destination, length of the header has not increased much from that of IPv4. This is because header format has been simplified in IPv6. You can see that among many elements (called "field") shown in Figure 1, those shown in red do not exist in Figure 2. One of the important changes is that there is no Options field in Figure 2. In IPv4, Options field can be used to add information about various optional services. For example, information related to encryption can be added here. Because of this, the length of the IPv4 header changes according to the situations. Due to this difference in length, routers that control communications according to the information in the IP header can't judge the length of the header just by looking at the beginning of the packet. This makes it difficult to speed up packet processing with hardware assist. On the other hand, IPv6 moves information related to additional services to a section called extension header. The part shown in Figure 2 is called basic header. Therefore, for plain packets, IP header length is fixed to 40 bytes. In terms of making it easier to process packets with hardware, you can say that IPv6 can be accelerated much easier than IPv4. Another field that exists in Figure 1 but is absent from Figure 2 is the Header Checksum field. A Header Checksum is a number used to check for errors in header information, and is calculated using the numbers in the header. However, problem with this approach is that header contains a number called TTL (Time To Live), which changes every time the packet goes through a router. Because of this, Header Checksum must be recalculated every time the packet goes through a router. If we can free up routers from this type of calculations, we could reduce the delay. Actually, TCP layer that resides above IP layer checks errors of various information including sender address and destination address. Since performing same calculations at the IP layer is redundant and unnecessary, Header Checksum is removed from IPv6. Figure 1 contains 8bit field called "Service Type". This field is used to represent the priority of the packet, for example whether it should be delivered express or with normal speed, and allows communication devices to handle the packet accordingly. Service Type field is composed of TOS (Type of Service) field and Precedence field. TOS field specifies the type of service and contains cost, reliability, throughput, delay, or security. Precedence field specifies the level of priority using eight levels from 0 to 7. IPv6 provides the same function with a field called Traffic Class. Flow Label field has a 20 bits length, and is a field newly established for IPv6. By using this field, packet's sender or intermediate devices can specify a series of packets, such as Voice over IP, as a flow, and request particular service for this flow. Even in the world of IPv4, some communication devices are equipped with the ability to recognize traffic flow and assign particular priority to each flow. However, these devices not only need to check the IP layer information such as address of the sender and the destination, but also need to check the port number which is an information that belongs to a higher layer. Flow Label field attempts to put together all these necessary information and provide them at the IP layer. However, specifics on how to use it is still undecided. As we have seen in this article, IPv6 aims to provide intelligent transmission framework that is easy to handle for intermediate devices by keeping the basic header simple and fixed length.

Related Questions

What is found on a datalink layer header?

The data link layer header contains the destination and source of information of the original frame and device sending information. You will also find that it contains the information of the device to receive it.


What information is added during encapsulation at the OSI layer 3 level?

At the OSI Layer 3, which is the Network layer, encapsulation involves adding a header to the data packet that includes crucial information for routing. This header contains the source and destination IP addresses, which facilitate the proper delivery of packets across different networks. Additionally, it may include other information such as the Time to Live (TTL) and protocol type, aiding in the management of the packet's journey through the network.


Which OSI layer header contains the address of a destination host that is on another?

Network Layer


What header information does a router change?

the Layer 2 source and destination address


Which OSI layer uses the header information to reassemble the data segments into streams?

transport layer


What information is found in the network layer header?

The destination host address


In which of the following would be found in a data link layer header?

The data link layer header contains the source's physical address. It refers the address that is found in the Network Interface Card.


What is the network transport layer?

Transport layer is responsible for reliable delivery of information, error correction and so on.


What is the use of adding header and trailer to the frames?

Trailer is added at only data link layer because data link layer provides error and flow control.Header Contains address of device where frames will be send


What protocols at other layers of the OSI model does ping use?

Layer 3 of the OSI model. An ICMP header follows the IP header of the IP packet.


Which OSI layer is responsible for adding a header that includes routing information?

The routing process occurs in the 3rd OSI layer (network layer) routing protocols use network address (IP address in TCP/IP) to chose the correct path to the destination. ps: You can also have routing protocols on other layers sometimes (application layer in p2p routing) but this is something completely different.


Why header and trailer is present in network layers?

HEADERS: It is a part of an information structure that precedes and identifies the information that follows,such as block of bytes in communication.TRAILERS:It is an information typically occupying several bytes ,at the tail end of a block of transmitted data which may contain a checksum or other error-checking data useful for confirming the accuracy and status of transmission.