Reassembly is intended to happen in the receiving host but in practice it may be done by an intermediate router, for example, network address translation (NAT) may need to reassemble fragments in order to translate data streams.

In the first one, The maximum transmission unit is 4000 bytes, and the second it is 2500 bytes.

Although originators may produce fragmented packets, IPv6 routers do not have the option to fragment further.

Instead, network equipment is required to deliver any IPv6 packets or packet fragments smaller than or equal to 1280 bytes and IPv6 hosts are required to determine the optimal MTU through Path MTU Discovery before sending packets.

They may also attempt to reassemble fragmented IP packets larger than 576 bytes, but they are also permitted to silently discard such larger packets.

Applications are recommended to refrain from sending packets larger than 576 bytes unless they have prior knowledge that the remote host is capable of accepting or reassembling them.

Applications relying upon IPv6 fragmentation to overcome a path MTU limitation must explicitly fragment the packet at the point of origin; however, they should not attempt to send fragmented packets with a total size larger than 1500 bytes unless they know in advance that the remote host is capable of reassembly.

The first is for the sending host to send an IP packet of size equal to the MTU of the first hop of the source-destination pair.

The second is to run the Path MTU Discovery algorithm 6 to determine the path MTU between two IP hosts so that IP fragmentation can be avoided.

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Ip Packet Reflect