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4.8

Retransmission

4.8.1 ARP & PING Retransmission

When there is no Response from Peer against of ARP or PING Request Packet, ARP & PING

Retransmission is performed.

In Retransmission Process, Request Packet is retransmitted every RTR until the Response Packet

received. And if the number of Retransmission exceeds RCR, TIMEOUT occurs for the Request

Packet.

The below table shows Retransmission TIMEOUT (ARPTO, PINGTO).

ARPTO, PINGTO = (TIMEOUTVAL x 0.1ms) x (TIMEOUTCNT + 1)

TIMEOUTVAL = SLRTR or Sn_RTR

TIMEOUTCNT = SLRCR or Sn_RCR

Ex) TIMEOUTVAL = 2000(0x07D0), TIMEOUTCNT = 8(0x0008)

ARPTO= 2000 X 0.1ms X 9 = 1.8s

ARPTO is caused by SLCR [ARP], Sn_CR [SEND] and Sn_CR [CONNECT]. And it is checked through

SLIR [TIMEOUT] or Sn_IR [TIMEOUT].

PINGTO is caused by SLCR [PING] and is checked through SLCR [TIMEOUT].

4.8.2 TCP Retransmission

When TCP Mode SOCKET does not receive ACK Packet from Peer against of SYN, FIN or DATA

Packet sent, TCP Retransmission is performed.

In TCP Retransmission process, Request Packet is retransmitted every Sn_RTR until Peer ACK

Packet received. And if the number of Retransmission exceeds Sn_RCR, SOCKET n TIMEOUT

occurs.

The below table shows TCP Retransmission TIMEOUT (TCPTO).

TCPTO = (∑(TIMEOUTVAL × 2N)

N=0

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

N :

Number of Retransmission, 0 ≤ N ≤ M

M :

Minimum value of TIMEOUTVAL × 2(��+1) >65535 and 0 ≤ M ≤ TIMEOUT

CNT

TIMEOUTVAL = SLRTR or Sn_RTR

TIMEOUTCNT = SLRCR or Sn_RCR

TIMEOUTMAXVAL: TIMEOUTVAL× 2��

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