Fragments other than the first fragment do not contain L4 headers, this makes life difficult for firewalls and network address translators.If the MTU of a path gradually reduces, then a number of small fragments can be created causing reduced routing efficiency.IPv4 fragmentation suffers from the following issues. IP does actually have a mechanism called "fragmentation" which can be used to divide oversized packets from an upper layer into smaller fragments but there are serveral issues with this mechanism. Splitting a data stream into packets or a packet into smaller packets is relatively cheap, but reassembly is relatively expensive as packets may arrive out of order and packets for multiple data streams may be interspersed. Generally in a network stack you want to perform each function once. If lower layer (like internet) have lower packet size why this has to do with TCP packet size limitations? That said the 1500 byte maximum most of the internet uses today is an anachronism. The larger the packet the more bandwidth is wasted retransmitting it. If a packet is damaged or a queue overflows, then typically the whole packet will be lost and will need to be retransmitted.Thus larger packets encounter more latency and take up more space in the buffers of forwarding devices. Most forwarding in packet switched networks is "store and forward", that is when a packet is received by a switch or router it is received in it's entirety before it is transmitted onwards.A larger packet has a longer transmission duration, which means it ties up the line for longer, increasing jitter for other (potentially higher priority) communication streams.In general there are several reasons to limit packet size. Basically, the data-link protocol is responsible for delivering frames in the local network, IP is responsible for delivering packets between networks, and a transport protocol like TCP is responsible for delivering datagrams between host processes on different hosts. Once you understand the reasons for the different layers in the network stack (abstraction and encapsulation), you will see how that works. TCP is a very large subject, far too large to explain it all in a site like this. The segments fit into the IP packets, which fit into the data-link protocol frames. TCP takes a stream of data (can be very large) and segments it into PDUs (Protocol Data Units) we call segments. If lower layer (like internet) have lower packet size why this has toĭo with TCP packet size limitations? a higher layer (than internet) So, in the simple case you get to share the circuit or path, and you lose very little in the event of a circuit or path interruption. If you break things up into smaller packets, and there is an interruption in the path, the rest of the packets can automatically be re-routed around the damage. The same holds true for a giant data packet. If you are making a call (say to respond to ICBM launches), and the telephone company central office is destroyed, then you lose the call and need to start all over, manually rerouting the call. The big driver of the government funding was the threat of disaster (including nuclear war, which was a big threat in the 1960s and 1970s). If the path loses a link, then the routers in the path can reroute packets to a different path to the destination, and the sender does not know or care. Each IP packet is routed independently, so a packet follows a path to the destination, regardless of the path any other packet took to the same destination. Breaking things up into smaller packets means that you can share the circuit among callers or processes. In a circuit-switched network, or what you propose, one caller or packet would monopolize the circuit or path until it is done, not giving anyone or any other process process a chance to use the circuit or path until it is done. The government funded research into packet-switched networks (result: Internet) to overcome the limitations of circuit-switched networks. That would just lead back to circuit-switched networks like the original PSTN (Public Switched Telephone Network). Into multiple pockets (ignoring size limit). Why we don't just send one single packet? why we need to split content
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