Maximum legal size of ICMP echo packet

networking icmp
Jake picture Jake · Feb 26, 2012 · Viewed 15.6k times · Source

Can someone please explain why maximum legal size of ICMP echo packet is calculated as follows:

65535 - 20 - 8 = 65507

Thanks.

Answer

Win32 picture Win32 · Feb 26, 2012

65535 bytes is the maximum allowed size of a IPv4 network packet, while 20 and 8 are the sizes of the IP and ICMP headers, which leaves up to 65507 bytes for the ICMP data.

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