RFC 4884:Extended ICMP to Support Multi-Part Messa...
RFC-Ref

1280 octet


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... ICMP message to exceed the minimum IPv6 MTU (i.e., 1280 octets). Unfortunately, the "original datagram ...


... reassembly buffer size (576 octets for ICMPv4 or 1280 octets for ICMPv6), there is no upper limit upon the length of the "original datagram ...



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