Brocade FastIron Ethernet Switch Administration Guide - Manual (Page 44)

Synchronizing time
After the system peer is chosen, the system time is synchronized based on the time difference with
system peer:
• If the time difference with the system peer is 128 msec and < 1000 sec, the system clock is stepped
to the system peer reference time and the NTP state information is cleared.
Authentication
The time kept on a machine is a critical resource, so it is highly recommended to use the encrypted
authentication mechanism.
The NTP can be configured to provide cryptographic authentication of messages with the clients/
peers, and with its upstream time server. Symmetric key scheme is supported for authentication. The
scheme uses MD5 keyed hash algorithm.
The authentication can be enabled using the authenticate command. The set of symmetric key and
key string is specified using the authentication-key command.
If authentication is enabled, NTP packets not having a valid MAC address are dropped.
If the NTP server/peer is configured without authentication keys, the NTP request is not sent to the
configured server/peer.
NOTE
The same set or subset of key id and key string should be installed on all NTP devices.
VLAN and NTP
When VLAN is configured,
• NTP time servers should be reachable through the interfaces which belong to the configured VLAN.
Otherwise, NTP packets are not transmitted. This is applicable to both the unicast and the
broadcast server/client.
• NTP broadcast packets are sent only on the interface which belongs to the configured VLAN.
• The received unicast or broadcast NTP packet are dropped if the interface on which packet has
been received does not belong to the configured VLAN
Configuring NTP
NTP services are disabled on all interfaces by default.
Prerequisites:
• Before you begin to configure NTP, you must use the clock set command to set the time on your
device to within 1000 seconds of the coordinated Universal Time (UTC).
• Disable SNTP by removing all the SNTP configurations.
Synchronizing time
44 FastIron Ethernet Switch Administration Guide
53-1003075-02