網路封包長度整理

- Ethernet Packet
Ethernet Header = ( 6 SRCMAC + 6 DSTMAC + 2 TYPE ) = 14 B
Ethernet Packet MinSize = ( 6 SRCMAC + 6 DSTMAC + 2 TYPE + 4 CRC + 46 PAYLOAD ) = 64 B
Ethernet Packet MaxSize = ( 6 SRCMAC + 6 DSTMAC + 2 TYPE + 4 CRC + 1500 PAYLOAD ) = 1518 B

- TCP Packet
Ethernet Header = 14 B
IP Header = 20 B
TCP Header MinSize = 20
TCP Header MaxSize = (20 TCP_HEADER + 40 OPTION) = 60 B

TCP Packet MinSize = ( 14 ETHERNET_HEADER + 20 IP_HEADER + 20 TCP_HEADER ) = 54 B
TCP Packet MaxSize = ( 14 ETHERNET_HEADER + 20 IP_HEADER + 60 TCP_HEADERP ) = 94 B

- UDP Packet
Ethernet Header = 14 B
IP Header = 20 B
UDP Header = 8 B

UDP Packet = ( 14 ETHERNET_HEADER + 20 IP_HEADER + 8 UDP_HEADER ) = 42 B



- PPPoE packet
PPP Header = 2 B
PPPoE Session = 6 B

TCP over PPPoE MinSize = ( 14 ETHERNET_HEADER + 6 PPPoE_SESSION + 2 PPP_HEADER + 20 IP_HEADER + 20 TCP_HEADER ) = 62 B 
TCP over PPPoE MaxSize = ( 14 ETHERNET_HEADER + 6 PPPoE_SESSION + 2 PPP_HEADER + 20 IP_HEADER + 60 TCP_HEADER ) = 102 B
UDP over PPPoE = ( 14 ETHERNET_HEADER + 6 PPPoE_SESSION + 2 PPP_HEADER + 20 IP_HEADER + 8 UDP_HEADER ) = 50 B
Ethernet IP MTU = 1518 - 18 ( 6 SRCMAC+ 6 DSTMAC+ 2 TYPE+ 4 CRC) = 1500 B
Ethernet IP TCP MSS = 1500 - 40 ( 20 IP_HEADER + 20 TCP_HEADER) = 1460 B
Ethernet IP UDP MTU/MRU = 1500 - 28 ( 20 IP_HEADER + 8 UDP_HEADER ) = 1472 B

PPPoE MTU/MRU = 1500 - 8 ( 6 PPPoE_SESSION + 2 PPP_HEADER ) = 1492 B
TCP over PPPoE MSS = 1492 ( PPPoE MTU/MRU ) - 40 ( 20 IP_HEADER + 20 TCP_HEADER) = 1452
UDP over PPPoE MTU/MRU = 1492 ( PPPoE MTU/MRU ) - 28 ( 20 IP_HEADER + 8 UDP_HEADER ) = 1464

PPTP MTU/MRU = 1500 - 56 ( 20 IP_HEADER + 20 TCP_HEADER + 12 GRE_HEADER + 4 PPP_HEADER ) = 1444 B
TCP over PPTP MSS = 1444 ( PPTP MTU/MRU ) - 40 ( 20 IP_HEADER + 20 TCP_HEADER) = 1404

L2TP MTU/MRU = 1500 - 40 ( 20 IP_HEADER +8 UDP_HEADER + 8 L2TP_HEADER + 4 PPP_HEADER ) = 1460 B
TCP over L2TP MSS = 1460 ( L2TP MTU/MRU ) - 40 ( 20 IP_HEADER + 20 TCP_HEADER) = 1420 B

PPTP over PPPoE MTU/MRU = 1492 ( PPPoE MTU/MRU ) - 56 ( 20 IP_HEADER + 20 TCP_HEADER + 12 GRE_HEADER + 4 PPP_HEADER ) = 1436 B

PPTP over PPTP MTU/MRU = 1444 ( PPTP MTU/MRU ) - 56 ( 20 IP_HEADER + 20 TCP_HEADER + 12 GRE_HEADER + 4 PPP_HEADER ) = 1388 B

PPTP over L2TP MTU/MRU = 1460 ( L2TP MTU/MRU ) - 56 ( 20 IP_HEADER + 20 TCP_HEADER + 12 GRE_HEADER + 4 PPP_HEADER ) = 1404 B

L2TP over PPPoE MTU/MRU = 1492 ( PPPoE MTU/MRU ) - 40 ( 20 IP_HEADER +8 UDP_HEADER + 8 L2TP_HEADER + 4 PPP_HEADER ) = 1452 B

L2TP over PPTP MTU/MRU = 1444 ( PPTP MTU/MRU ) - 40 ( 20 IP_HEADER +8 UDP_HEADER + 8 L2TP_HEADER + 4 PPP_HEADER ) = 1404 B

L2TP over L2TP MTU/MRU = 1460 ( L2TP MTU/MRU ) - 40 ( 20 IP_HEADER +8 UDP_HEADER + 8 L2TP_HEADER + 4 PPP_HEADER ) = 1420 B