Brocade Multi-Service IronWare Administration Guide (Supporting R05.6.00) - Manual (Page 281)

Multi-Service IronWare Administration Guide 263
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How NTP works
7
How NTP works
NTP server
A NTP server will provide the correct network time on your device using the Network time protocol
(NTP). Network Time Protocol can be used to synchronize the time on devices across a network. A
NTP time server is used to obtain the correct time from a time source and adjust the local time in
each connecting device.
The NTP server can operate in master mode to serve time using the local clock, when it has lost
synchronization.
NTP client
An NTP client gets time responses from an NTP server or servers, and uses the information to
calibrate its clock. This consists of the client determining how far its clock is off and adjusting its
time to match that of the server. The maximum error is determined based on the round-trip time for
the packet to be received.
NTP peer
NTP peer mode is intended for configurations where a group of devices operate as mutual backups
for each other. If one of the devices lose a reference source, the time values can flow from the
surviving peers to all the others.
The NTP peer can operate in:
Symmetric Active - When the peer is configured using the peer command.
Symmetric Passive – Dynamically learnt upon arrival of a NTP packet from the peer which is not
configured. The symmetric passive association is removed on timeout or error.
NTP broadcast server
An NTP server can also operate in a broadcast or multicast mode. Both work similarly; 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.