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Fragmentation is resource intensive in a router, and it slows packet forwarding. Today, we use PMTUD to determine the smallest MTU in the path so that packets are properly sized prior to sending. There are also fragmentation attacks, so many businesses drop fragments. What you are confusing is something like TCP segmentation, which is very different than ...


8

IP packet level fragmentation occurs when the transmitting side is not properly aware of the MTU of the path. This results in worse performance than if the packets are sized correctly already at the endpoint. For example, if the transmitting side of a TCP connection believes the path MTU to be 1500 bytes, it will send packets of that size. If the real path ...


6

IP fragmentation can cause excessive retransmission at the TCP level. TCP transmits information as a series of segments, and these are the units of acknowledgement and retransmission as well. If a TCP segment is lost in the network, the entire segment has to be retransmitted. If IP fragmentation occurs, the segment will be split into multiple fragments. The ...


6

YES. If the MTU somewhere along the path is smaller than your packet size, it will be fragmented. This may not apply in your simple network, but it's possible in the real world. One thing isn't clear from your description: sockets are stream-oriented. The stack will handle the fragmenting/defragmenting for you. I'm not sure why you're concerned.


5

Can the network devices on the path fragment my packet for a reason? If it is IPv4, and the DF bit is clear, then yes, your packets can be fragmented in the path. The fragmentation and reassembly will be transparent to your application. Packets can get fragmented in the path, then the destination host will reassemble them at IPv4 before passing the packet ...


2

How to determine the distinct TCP segments or IP packets or fragments within a TCP Window? Each segment is sent in a separate IP packet. Once reassembly of the original stream has started within the receive buffer (or window, if you like), you cannot make out which data went in which segment any more. While the segments are still in transport, you can see ...


1

I am not really sure I understand what is the end goal here but technically there is a way to achieve what you're looking for. In order to do this you'd need to capture the beginning of the TCP conversation as this is the only place where during the three-way handshake parameters are agreed. Those parameters are quite important when it comes to TCP window (...


1

If there is IP fragmentation, is there also Ethernet fragmentation? No, there's no such thing. Of course, you can break a frame into multiple pieces when transporting over another protocol like ATM. The frame splitting and reassembly would need to happen somewhere in between the original Ethernet transport and that other protocol. However, Ethernet has no ...


1

I have it set up where I have a 64KB memory space so fragments can arrive in any order. A 64K buffer is actually a mistake because it leads to a particular fragment attack where the bad guys can send packets that add up to more than 64K, causing a buffer overflow. Is it a requirement for clients of any type to send the fragments in sequential order from ...


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