Nortel Contivity 1100 Configuration Manual page 107

NTP supports the 2007 Daylight Savings Time change in the United States and
various Canadian provinces. In 2007, Daylight Savings Time begins at 2 a.m. on
the second Sunday in March and ends at 2 a.m. on the first Sunday in November.
To configure NTP:
1
Click on the Enable check box.
2
If you want the Nortel VPN Router to listen for and respond to broadcast
messages, check the Synchronize time with NTP Broadcast Server box. If you
want the Nortel VPN Router to listen for and respond to multicast messages,
check the Synchronize time with NTP Multicast Server box. The IP multicast
address is 224.0.1.1 for NTP. NTP listens for both broadcast and multicast
messages at the group address of the global network. To avoid disruption in
multicast mode, both the client and servers should use authentication and the
same trusted key and key identifier.
3
Under Servers, click Add to add a server:
a
IP address of the NTP (unicast) server.
b Under Interface, for security, you can specify either a private or public
interface. The private interface is the management IP address. When
adding a public interface, you can choose from a list of public interfaces.
If you are using the Nortel VPN Router Firewall, you need to configure an
interface filter to add NTP.
c
Enter the Key ID. This specifies the Key ID for Message Digest (MD5)
authentication. In authentication mode, each packet transmitted has a
32-bit Key ID and a 64/128-bit cryptographic checksum using MD5
algorithms. With MD5, the receiving peer recomputes the checksum and
compares it with the one in the packet. They must share at least one MD5
key (trusted key) and must associate the shared key with the same Key ID.
d Enable Bursting to send a burst of eight packets at each poll interval.
e Select the NTP version number (1, 2, 3, or 4) used on the NTP server. The
default is 3.
f Click OK.
4 Under Trusted Keys, click on the Add button to add an area key ID. The
Nortel VPN Router displays the Add/Edit Trusted Key window. Enter the key
ID, the password and the password confirmation.
Chapter 5 Configuring the system 107
Nortel VPN Router Configuration — Basic Features