What is minimum size of MTU in IPv4?
576 bytes
The MTU should not be confused with the minimum datagram size that all hosts must be prepared to accept. This is 576 bytes for IPv4 and of 1280 bytes for IPv6. Systems may use Path MTU Discovery to find the actual path MTU. Routing from larger MTU to smaller MTU causes IP fragmentation.
What is minimum MTU?
This value is called the maximum transmission unit (MTU), or maximum packet size in TCP/IP terms. RFC 791 —Internet Protocols states that all IP hosts must be prepared to accept datagrams of up to 576 bytes. The minimum MTU for IPv6 is 1280.
What is the minimum packet size in IPv4?
20 bytes
The minimum size is 20 bytes (header without data) and the maximum is 65,535 bytes. All hosts are required to be able to reassemble datagrams of size up to 576 bytes, but most modern hosts handle much larger packets.
Is there a low MTU requirement for IPv6?
However such a low MTU would be extremely inefficient. IPv6 sets a much higher minimum of 1280 bytes and requires links that can’t support that MTU to provide a link-specific fragmentation and reassembly layer. From https://tools.ietf.org/html/rfc2460
How big is a 68 byte IPv4 packet?
So the RFC is basically saying that, for a router, the biggest possible IP header is 60 bytes and the smallest payload is 8 bytes (so, a 68 byte packet).
Which is the minimum size of an IPv4 header?
The minimum size of a IPv4 header is 20 bytes and not 60. So shouldn’t the minimum MTU be 20 bytes for the IPv4 header plus the minimum fragment which is 8 bytes? And shouldn’t we consider the upper layer header lengths as well?
What is the maximum size of an IPv4 datagram?
The IPv4 datagram consists of two parts:the header length and the payload. The maximum header size is 60 bytes and minimum is 20 bytes. The maximum size of the data can be 65515 bytes.