Cisco 7940G Administration Manual page 20

How to Set the Date and Time
Table 3-4
or when it is assigned a valid IP address.
Table 3-4
SNTP
Server
SNTP server parameter is null
Sends
Receives
SNTP server parameter is a valid IP address.
Sends
Receives
1. If sntp_mode is set to anycast, the sntp_server address will be ignored and subsequent sntp requests will be sent to the first
sntp server that responded (the first sntp request must be unconditionally sent to the broadcast address).
Cisco Unified IP Phone 7960G and 7940G Administration Guide for Release 8.0 (SIP)
3-20
describes the effects on SNTP mode when the SNTP server is null (not assigned an IP address)
Effects on SNTP Mode
SNTP Mode
Unicast Multicast
No known server SNTP requests are
with which to not sent.
communicate.
No known server Multicast data using
with which to the SNTP/NTP
communicate. multicast address
from the local
network broadcast
address from any
server on the
network.
SNTP request to the SNTP requests are
SNTP server. not sent.
SNTP response from SNTP data via the
the SNTP server and SNTP/NTP multicast
ignores responses address from the
from other SNTP local network
servers. broadcast address.
Chapter 3 Initializing Cisco Unified IP Phones
1
Anycast Directed Broadcast
SNTP packet to the SNTP packet to the
local network local network
broadcast address. broadcast address.
After the first SNTP After the first SNTP
response is received, response is received,
the phone switches the phone switches
to unicast mode with to multicast mode.
the server being set
as the one who first
responded.
Unicast SNTP data SNTP data from the
from the SNTP SNTP/NTP multicast
server that first address and the local
responded to the network broadcast
network broadcast address from any
request. server on the
network.
If the mode is SNTP packet to the
anycast and the SNTP server.
SNTP server
After the first SNTP
parameter is a valid
response is received,
IP address, the phone
the phone switches
sends the request to
to multicast mode.
the broadcast address
in version 7.4.
SNTP response from SNTP data from the
the SNTP server and SNTP/NTP multicast
ignores responses address and the local
from other SNTP network broadcast
servers. address and ignores
responses from other
SNTP servers.
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