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Cisco SIP IP Phone Administrator Guide
Chapter 3 Managing Cisco SIP IP Phones
Setting the Date, Time, and Daylight Saving Time
Table 3-9
lists the actions that take place when a valid IP address is specified in the sntp_server
parameter.
Step 1
Using an ASCII editor, open the SIPDefault.cnf file and define or modify values for the following
SNTP-specific SIP parameters as necessary:
•
sntp_mode—(Required) Mode in which the phone listens for the SNTP server. Valid values are
unicast, multicast, anycast, or directedbroadcast.
See
Table 3-8
and
Table 3-9
for an explanation on how these values work, depending on the
sntp_server parameter value.
•
sntp_server—(Required) IP address of the SNTP server from which the phone will obtain time data.
Table 3-8
Actions Based on sntp_mode When the sntp_server Parameter Is Set to a Null Value
sntp_server
=0.0.0.0
sntp_mode=
unicast
sntp_mode=
multicast
sntp_mode=
anycast
sntp mode=
directedbroadcast
Sends
Nothing.
No known server with
which to communicate.
Nothing.
When in multicast mode,
SNTP requests are not
sent.
SNTP packet to the local
network broadcast address.
After the first SNTP
response is received, the
phone switches to unicast
mode with the server being
set as the one who first
responded.
SNTP packet to the local
network broadcast
address.
After the first SNTP
response is received, the
phone switches to
multicast mode.
Receives
Nothing.
No known server with
which to communicate.
SNTP data via the
SNTP/NTP multicast
address from the local
network broadcast address
from any server on the
network.
Unicast SNTP data from the
SNTP server that first
responded to the network
broadcast request.
SNTP data from the
SNTP/NTP multicast
address and the local
network broadcast
address from any server
on the network.
Table 3-9
Actions Based on sntp_mode When the sntp_server Parameter Is Set to an IP Address
sntp_server
= 192.168.1.9
sntp_mode=
unicast
sntp_mode=
multicast
sntp_mode=
anycast
sntp_mode=
directedbroadcast
Sends
SNTP request to the
SNTP server.
Nothing.
When in multicast mode,
SNTP requests are not sent.
SNTP request to the SNTP
server.
SNTP packet to the
SNTP server.
After the first SNTP
response is received, the
phone switches to
multicast mode.
Receives
SNTP response from the
SNTP server and ignores
responses from other
SNTP servers.
SNTP data via the
SNTP/NTP multicast
address from the local
network broadcast address.
SNTP response from the
SNTP server and ignores
responses from other
SNTP servers.
SNTP data from the
SNTP/NTP multicast
address and the local
network broadcast
address and ignores
responses from other
SNTP servers.
