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15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
res
RC[7:0]
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
RCR configures the number of time of retransmission. When retransmission occurs as many
as „RCR+1‟, Timeout interrupt is issued (Sn_IR[TIMEOUT] = „1‟).
When RCR is not „0x0000_0000, RCR is used to configure the timeout period of all socket.
When RCR is „0x0000_0000‟, the timeout period of each socket could set by using Socket n
Retry Counter Register (Sn_RCR).
Ex) RCR = 0x0007
RC[7:0]
0x07
The timeout of WZTOE can be configurable with RTR and RCR. WZTOE has two kind timeout
such as Address Resolution Protocol (ARP) and TCP retransmission.
At the ARP (Refer to RFC 826, http://www.ietf.org/rfc.html) retransmission timeout, WZTOE
automatically sends ARP-request to the peer‟s IP address in order to acquire MAC address
information (used for communication of IP, UDP, or TCP). While waiting for ARP-response
from the peer, if there is no response during the configured RTR time, a temporary timeout
is occurred and ARP-request is retransmitted. It is repeated as many as „RCR + 1‟ times. Even
after the ARP-request retransmissions are repeated as „RCR+1‟ and there is no response to
the ARP-request, the final timeout is occurred and Sn_IR(TIMEOUT) becomes „1‟. The time of
final timeout (ARP
) of ARP-request is as below.
TO
(
)
(
)
��
At the TCP packet retransmission timeout, WZTOE transmits TCP packets (SYN, FIN, RST,
DATA packets) and waits for the acknowledgement (ACK) during the configured RTR time and
RCR. If there is no ACK from the peer, a temporary timeout occurs and the TCP packet is
retransmitted. The retransmission is repeated as many as „RCR+1‟. Even after TCP
retransmission is repeated as „RCR+1‟ and there is no response to the TCP retransmission,
the final timeout is occurred and Sn_IR(TIMEOUT) becomes „1‟. The time of final timeout
(TCPTO) of TCP retransmission is as below.
60 / 512
W7500 Datasheet Version1.0.0
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