Dell N1100-ON, Reference Manual

Page: 1845 / 2332

Switch Management Commands
1845
Clock Commands
Real-time Clock
The Dell EMC Networking supports a real-time clock that maintains the
system time across reboots. The system time is used to timestamp messages
in the logging subsystem as well as for the application of time based ACLs.
The administrator has the ability to configure and view the current time, time
zone, and summer time settings.
The earliest date that can be configured is Jan 1, 2010.
Simple Network Time Protocol
The Simple Network Time Protocol (SNTP) is widely used for synchronizing
network resources. SNTP Version 4 is described in RFC 2030. SNTP is an
adaptation of the Network Time Protocol (RFC 1305) useful for situations
where the full performance of NTP is not justified. SNTP can operate in
unicast mode (point-to-point) or broadcast mode (point-to-multipoint).
Various NTP implementations can operate as either a client or a server. To an
NTP or SNTP server, NTP and SNTP clients are indistinguishable. Likewise,
to an NTP or SNTP client, NTP and SNTP servers are indistinguishable.
Furthermore, any version of NTP is compatible with any other version of NTP.
Dell EMC Networking SNTP implements the client side of SNTP.
Support for IPv6 address configuration is provided to the existing SNTP
client. The end user can configure either an IPv4 or IPv6 address or a host
name for an SNTP server among the list of servers. In unicast mode, one of
the servers from the list is selected as the active server to be used for polling
based on priority and configured order. The servers are treated alike
independent of IPv4 or IPv6 or hostname address formats. At any given point
of time, the client operates in unicast or broadcast mode. In broadcast mode,
SNTP client listens on the well known multicast group address 224.0.1.1
(reserved for NTP) for server packets from IPv4 networks on port number 123.
On IPv6 networks, the SNTP client listens to the link-local scoped IANA
multicast address ff02::101 (reserved for SNTP) for server packets on port
number 123. The client logic to handle packet contents doesn’t change with
support for IPv6 networks.