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GS700TR Smart Switch Software Administration Manual
2-6 Configuring System Information
v1.0, May, 2008
• T1: Time at which the original request was sent by the client.
• T2: Time at which the original request was received by the server.
• T3: Time at which the server sent a reply.
• T4: Time at which the client received the server's reply.
The device can poll Unicast and Broadcast server types for the server time.
Polling for Unicast information is used for polling a server for which the IP address is known.
SNTP servers that have been configured on the device are the only ones that are polled for
synchronization information. T1 through T4 are used to determine server time. This is the
preferred method for synchronizing device time because it is the most secure method. If this
method is selected, SNTP information is accepted only from SNTP servers defined on the device
using the SNTP Server Configuration page.
Broadcast information is used when the server IP address is unknown. When a Broadcast message
is sent from an SNTP server, the SNTP client listens to the message. If Broadcast polling is
enabled, any synchronization information is accepted, even if it has not been requested by the
device. This is the least secure method.
The device retrieves synchronization information, either by actively requesting information or at
every poll interval. If Unicast and Broadcast polling are enabled, the information is retrieved in
this order:
• Information from servers defined on the device is preferred. If Unicast polling is not enabled
or if no servers are defined on the device, the device accepts time information from any SNTP
server that responds.
• If more than one Unicast device responds, synchronization information is preferred from the
device with the lowest stratum.
• If the servers have the same stratum, synchronization information is accepted from the SNTP
server that responded first.
MD5 (Message Digest 5) Authentication safeguards device synchronization paths to SNTP
servers. MD5 is an algorithm that produces a 128-bit hash. MD5 is a variation of MD4, and
increases MD4 security. MD5 verifies the integrity of the communication, authenticates the origin
of the communication.