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Sidewinder G2 6.1.1 Administration Guide - Glossary of Technical ...

Sidewinder G2 6.1.1 Administration Guide - Glossary of Technical ...

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Overview<br />

Figure B-3. The<br />

<strong>Sidewinder</strong> <strong>G2</strong> as an NTP<br />

server—external time<br />

servers supply time to<br />

the <strong>Sidewinder</strong> <strong>G2</strong>, which<br />

passes time on to the<br />

internal system (multiple<br />

servers provide backup)<br />

B-4 Setting Up Network Time Protocol<br />

Important: Unlike the previous two configurations, an external-to-internal NTP<br />

configuration may introduce security concerns to the <strong>Sidewinder</strong> <strong>G2</strong> and thus to your<br />

network. Therefore, this configuration is only recommended for sites that need world<br />

standard time.<br />

Note: For the configuration shown in Figure B-3, the router must be able to handle NTP<br />

traffic.<br />

time from the<br />

<strong>Sidewinder</strong><br />

time-feed<br />

internal<br />

network<br />

Router<br />

Servers on external network<br />

supply time to the <strong>Sidewinder</strong><br />

To pass a clock setting to the internal network, the external side <strong>of</strong> the<br />

<strong>Sidewinder</strong> <strong>G2</strong> needs to be configured as a client to the external clocks.<br />

The <strong>Sidewinder</strong> <strong>G2</strong>’s NTP client then takes the "tick" from the remote<br />

clock, and sends it to the on-board system clock. On the internal side<br />

<strong>of</strong> the <strong>Sidewinder</strong> <strong>G2</strong>, the NTP server is enabled with the clock type<br />

set to "local." This forces the <strong>Sidewinder</strong> <strong>G2</strong> to look to its internal<br />

clock for the time information, and configured as an internal server,<br />

pass the "tick" to the server on the internal burb interface.<br />

NTP must also be configured on each <strong>of</strong> the external time servers. For<br />

certified time servers, it is safe to assume that this has already been<br />

done correctly.<br />

Note: An external NTP configuration is recommended only for sites that require time<br />

within microseconds <strong>of</strong> world standard time. This is achieved by configuring NTP on the<br />

<strong>Sidewinder</strong> <strong>G2</strong> to accept time signals from one or more certified time servers located<br />

outside your company network. For a list <strong>of</strong> certified time servers, check the following Web<br />

site:<br />

http://www.eecis.udel.edu/~mills/ntp/servers.html<br />

The list includes stratum1 and stratum2 servers. Be sure to select stratum2 servers only. It is<br />

also best to choose a time server that is located within your time zone.<br />

R

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