Brocade Multi-Service IronWare Administration Guide (Supporting R05.6.00) - Manual (Page 279)

Multi-Service IronWare Administration Guide 261
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Chapter
7
Network Time Protocol
Network Time Protocol (NTP) overview
Network Time Protocol (NTP) maintains uniform time across all devices in a network. The NTP
commands support the configuration of an external time server to maintain synchronization
between all local clocks in a network.
NTP has a hierarchical structure. At the highest level, or stratum, are precise hardware clocks,
which can synchronize to highly accurate external time reference. These hardware clock devices
are known as stratum 0 devices. A stratum 1 time server obtains time directly from a hardware
clock and is the most accurate reference in the NTP hierarchy. All lower stratum devices obtain
time from the stratum above over a network. As the network introduces timing discrepancies, lower
stratum devices are a factor less accurate.
A hierarchical structure allows the overhead of providing time to many clients to be shared among
many time servers. Not all clients need to obtain time directly from a stratum 1 reference, but can
utilise stratum 2 or 3 references.
NTP operates on a client-server basis. A network time client periodically requests time from a time
server. The time server responds with a packet of information containing a time stamp. The time
stamp is then used by the client to synchronize its system time.
NTP uses UTC (Universal Time Coordinated) time, which is similar to GMT time. It knows nothing of
local time zones or daylight-saving time. It is a function of the time client to apply an offset to the
supplied time to adjust for local time. In this manner, a time server located anywhere in the world
can provide synchronisation to a client located anywhere else in the world. It allows clients to utilise
different time zone and daylight-saving properties.
To keep the time in your network current, it is recommended that each device have its time
synchronized with at least four external NTP servers. External NTP servers should be synchronized
among themselves in order to maintain time synchronization.
NOTE
Network Time Protocol (NTP) commands must be configured on each individual device.
TABLE 36 Supported platforms for NTPs
Features
supported Brocade
NetIron XMR Brocade
MLX Series Brocade
NetIron CES
2000 Series
BASE
package Brocade
NetIron CES
2000 Series
ME_PREM
package Brocade
NetIron CES
2000 Series
L3_PREM
package Brocade
NetIron CER
2000 Series
Base
package Brocade
NetIron CER
2000 Series
Advanced
Services
package
Network Time
Protocol Yes Yes Yes Yes Yes Yes Yes