Dell PowerConnect M6220, User Configuration Manual

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Managing General System Settings
You can configure the switch to request the time from an SNTP server on the
network, or you can allow the switch to receive SNTP broadcasts.
Requesting the time from a unicast SNTP server is more secure. Use this
method if you know the IP address of the SNTP server on your network. If you
allow the switch to receive SNTP broadcasts, any clock synchronization
information is accepted, even if it has not been requested by the device. This
method is less secure than polling a specified SNTP server.
To increase security, you can require authentication between the configured
SNTP server and the SNTP client on the switch. Authentication is provided
by Message Digest 5 (MD5). MD5 verifies the integrity of the
communication and authenticates the origin of the communication.
What Configuration Is Required for Plug-In Modules?
The switch supports several different plug-in modules (also known as cards)
for the expansion slots located on the back of the switch. For information
about the slots and the supported modules, see "PowerConnect M6220,
M6348, M8024, and M8024-k Front Panel" on page 87. You can preconfigure
the card type prior to inserting it into the switch.
Hot-swap support is not available for plug-in modules, which means the
switch requires a reboot when you insert or remove cards. Additionally, the
switch must be powered off to change the role of the ports on a module from
stacking to Ethernet or vice-versa. Modules operate in the mode for which
they are configured as a default. This means that the module configuration
(Ethernet or stacking) does not appear in the running-config.
Before inserting a new module into the expansion slot that was previously
occupied by a different type of module, issue a no slot or clear config
command from the CLI so that the switch can recognize the new module.