W6100 datasheet(131/149 Pages) WIZNET

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W6100 – Hardwired Dual TCP/IP Stack Controller

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PINGTO occurs when there is no response from a destination in ARP-process by SLCR[PING] and

SLCR[PING6] or no PING reply from a destination after ARP-process.

SLIR[TOUT] is set by PINGTO.

NDTO occurs in the ND process by Sn_CR[CONNECT6] in TCP6 & TCPD mode, Sn_CR[SEND6] in

UDP6 & UDPD & IPRAW6 mode, SLCR[ARP6] & SLCR[NS] & SLCR[RS] in SOCKET-less command.

Sn_IR[TIMEOUT] or SLIR[TOUT] is set by NDTO.

6.7.2 TCP Retransmission

When TCP mode SOCKET doesn’t receive ACK packet from a destination against of SYN, FIN,

or DATA packet sent, TCP retransmission is performed. In TCP retransmission process, the

packet is retransmitted every Sn_RTR until ACK packet from the destination is received. And

if the count of retransmission exceeds Sn_RCR, SOCKET n TIMEOUT occurs.

The below table shows the TCP Retransmission TIMEOUT (TCPTO).

TCPTO = (∑(TIMEOUTVAL × 2N)

N=0

+ ((TIMEOUTCNT − M) × TIMEOUTMAXVAL)) × 0.1ms

N : Retransmission Counter, 0 ≤ N ≤ M

M : TIMEOUTVAL × 2(��+1) >65535 and 0 ≤ M ≤ TIMEOUT

CNT 에서의 최소값

TIMEOUTVAL = Sn_RTR

TIMEOUTCNT = Sn_RCR

TIMEOUTMAXVAL: TIMEOUTVAL× 2��

Ex) RTR = 2000(0x07D0), RCR = 8(0x0008)

TCPTO = (0x07D0+0x0FA0+0x1F40+0x3E80+0x7D00+0xFA00+0xFA00+0xFA00+0xFA00) X 0.1ms

= (2000 + 4000 + 8000 + 16000 + 32000 + ((8 - 4) X 64000)) X 0.1ms

= 318000 X 0.1ms = 31.8s

TCPTO occur by CONNECT, CONNECT6, SEND, SEND6, and DISCON command in Sn_CR, and

Sn_IR [TIMEOUT] is set by TCPTO.

W6100 Datasheet(PDF) 131 Page - WIZnet Co., Ltd