In IPv6 payload field if I make all bits 0 then minimum IPv6 packet size should be 40 bytes(only header), but I read in RFC that minimum IPv6 payload should be 1280 bytes. Am I correct?
If yes, why 1280 is chosen as the minimum payload size?
Thanks & Regards, Fahad Ahmed
This question is marked "community wiki".
The reference to 1280 bytes in RFC2460 that you are referring to is the smallest permissible value for the MTU (Maximum Transmission Unit) for a network link. i.e. All network links transporting IPv6 must be able to carry packets of at least 1280 bytes. Most links have an MTU of 1500 bytes.
For IPv4, the smallest permissible MTU was 576 bytes; so this value has been increased a bit as part of the move to IPv6.
I think you're right that a 40 byte IPv6 packet (only a header with no options or payload) is the minimum size of IPv6 packet.
answered 21 Nov '11, 20:35