Size of empty UDP and TCP packet?

tcp udp size
puccio picture puccio · Dec 4, 2009 · Viewed 89.1k times · Source

What is the size of an empty UDP datagram? And that of an empty TCP packet?

I can only find info about the MTU, but I want to know what is the "base" size of these, in order to estimate bandwidth consumption for protocols on top of them.

Answer

Himanshu picture Himanshu · Dec 4, 2009

TCP:

Size of Ethernet frame - 24 Bytes
Size of IPv4 Header (without any options) - 20 bytes
Size of TCP Header (without any options) - 20 Bytes

Total size of an Ethernet Frame carrying an IP Packet with an empty TCP Segment - 24 + 20 + 20 = 64 bytes

UDP:

Size of Ethernet frame - 24 Bytes
Size of IPv4 Header (without any options) - 20 bytes
Size of UDP header - 8 bytes

Total size of an Ethernet Frame carrying an IP Packet with an empty UDP Datagram - 24 + 20 + 8 = 52 bytes

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