About Ntp; Ntp Configuration Guidelines - Cisco AP776A - Nexus Converged Network Switch 5020 Configuration Manual

NTP Configuration
S e n d d o c u m e n t a t i o n c o m m e n t s t o m d s f e e d b a c k - d o c @ c i s c o . c o m
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About NTP

In a large enterprise network, having one time standard for all network devices is critical for management
reporting and event logging functions when trying to correlate interacting events logged across multiple
devices. Many enterprise customers with extremely mission-critical networks maintain their own
stratum-1 NTP source.
Time synchronization happens when several frames are exchanged between clients and servers. The
switches in client mode know the address of one or more NTP servers. The servers act as the time source
and receive client synchronization requests.
By configuring an IP address as a peer, the switch will obtain and provide time as required. The peer is
capable of providing time on its own and is capable of having a server configured. If both these instances
point to different time servers, your NTP service is more reliable. Thus, even if the active server link is
lost, you can still maintain the right time due to the presence of the peer.
Tip If an active server fails, a configured peer helps in providing the NTP time. Provide a direct NTP server
association and configure a peer to ensure backup support if the active server fails.
If you only configure a peer, the most accurate peer takes on the role of the NTP server and the other
peer(s) acts as a peer(s). Both machines end at the right time if they have the right time source or if they
point to the right NTP source.

NTP Configuration Guidelines

The following guidelines apply to all NTP configurations:
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Not even a server down time will affect well-configured switches in the network.
network with two NTP stratum 2 servers and two switches.
Cisco MDS 9000 Family CLI Configuration Guide
5-20
NTP Configuration Guidelines, page 5-20
Configuring NTP, page 5-21
NTP CFS Distribution, page 5-24
You should have a peer association with another switch only when you are sure that your clock is
reliable (which means that you are a client of a reliable NTP server).
A peer configured alone takes on the role of a server and should be used as backup. If you have two
servers, then you can have several switches point to one server, and the remaining switches to the
other server. Then you would configure peer association between these two sets. This forces the
clock to be more reliable.
If you only have one server, all of the switches should have a client association with that server.
Chapter 5 Initial Configuration
Figure 5-3
OL-18084-01, Cisco MDS NX-OS Release 4.x
displays a