net-sntp-unicast.html
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>Configuring the unicast list of NTP servers</A
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>If SNTP unicast mode is enabled via the CYGPKG_NET_SNTP_UNICAST
option, the SNTP client can be configured with a list of
NTP servers to contact for time updates.</P
><P
>By default, this list is configured with NTP server information
received from DHCP. The number of NTP servers that are extracted
from DHCP can be configured with the CYGOPT_NET_SNTP_UNICAST_MAXDHCP
option. This option can also be used to disable DHCP usage entirely.</P
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>The list of NTP servers can be manually configured with the following
API function. Note that manual configuration will override any
servers that were automatically configured by DHCP. But later
reconfigurations by DHCP will override manual configurations. Hence it
is not recommended to manually configure servers when
CYGOPT_NET_SNTP_UNICAST is enabled.</P
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>#include <cyg/sntp/sntp.h>
void cyg_sntp_set_servers(struct sockaddr *server_list, cyg_uint32 num_servers);</PRE
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>This function takes an array of sockaddr structures specifying the
IP address and UDP port of each NTP server to query. Currently,
both IPv4 and IPv6 sockaddr structures are supported. The
num_servers argument specifies how many sockaddr's are contained
in the array. The server_list array must be maintained by the caller.
Once the array is registered with this function, it must not be
modified by the caller until it is replaced or unregistered
by another call to this function.</P
><P
>Calling this function with a server_list of NULL and a num_servers
value of 0 unregisters any previously configured server_list array.</P
><P
>Finally, note that if this function is called with a non-empty server
list, it will implicitly start the SNTP client if it has not already
been started (i.e. it will call cyg_sntp_start()).</P
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