Technical data

26 FastIron Ethernet Switch Administration Guide

53-1002637-02

Network Time Protocol Version 4 (NTPv4)

The following scenarios are observed when you remove the last NTP server/peer under the

conditions - the NTP server/peer is configured, master command is not configured, system clock is

synchronized and the reference time is the NTP time:

• If the local clock is not valid, the system clock is not synchronized.

• If the local clock is valid, the system clock is synchronized and the reference time is the local

clock. The server will respond to the client's request with the specified stratum number if it is

configured otherwise with the default stratum number.

NOTE

To create a symmetric active association when a passive association is already formed, disable NTP,

configure peer association and then enable NTP again.

NTP broadcast server

An NTP server can also operate in a broadcast mode. Broadcast servers send periodic time

updates to a broadcast address, while multicast servers send periodic updates to a multicast

address. Using broadcast packets can greatly reduce the NTP traffic on a network, especially for a

network with many NTP clients.

The interfaces should be enabled with NTP broadcasting. The NTP broadcast server broadcasts the

NTP packets periodically (every 64 sec) to subnet broadcast IP address of the configured interface.

• NTP broadcast packets are sent to the configured subnet when the NTP broadcast server is

configured on the interface which is up and the IP address is configured for the broadcast

subnet under the following conditions:

• The local clock is valid and the system clock is synchronized

• The local clock is valid and the system clock is not synchronized

• Authentication key is configured, the system clock is synchronized and the local clock is

valid

• NTP broadcast packets are not sent in the following cases:

• NTP broadcast server is configured on the interface which is down even if the system clock

is synchronized and the local clock is valid.

• NTP broadcast server is configured on the interface which is up and no IP address is

configured for the broadcast subnet even if the system clock is synchronized and the local

clock is valid.

• NTP broadcast server is configured on the interface which is not present and no IP

address is configured for the broadcast subnet even if the system clock is synchronized

and the local clock is valid.

• NTP broadcast server without authentication key is configured on the interface which is up

and the IP address is configured for the broadcast subnet even when NTP authentication

is enforced and the system clock is synchronized and the local clock is valid.