NETGEAR GS748T User Manual

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GS748T Smart Switch
Time
GS748T Smart Switch software supports the Simple Network Time Protocol (SNTP). You can
also set the system time manually
SNTP assures accurate network device clock time synchronization up to the millisecond.
Time synchronization is performed by a network SNTP server. GS748T Smart Switch
software operates only as an SNTP client and cannot provide time services to other systems.
Time sources are established by Stratums. Stratums define the accuracy of the reference
clock. The higher the stratum (where zero is the highest), the more accurate the clock. The
device receives time from stratum 1 and above since it is itself a stratum 2 device.
The following is an example of stratums:
• Stratum 0: A real-time clock is used as the time source, for example, a GPS system.
• Stratum 1: A server that is directly linked to a Stratum 0 time source is used. Stratum 1
time servers provide primary network time standards.
• Stratum 2: The time source is distanced from the Stratum 1 server over a network path.
For example, a Stratum 2 server receives the time over a network link, via NTP, from a
Stratum 1 server.
Information received from SNTP servers is evaluated based on the time level and server
type.
Neighbor State Specifies the state of the neighbor cache entry. The following are the states for
dynamic entries in the IPv6 neighbor discovery cache:
• Reachable. Positive confirmation was received within the last Reachable Time
milliseconds that the forward path to the neighbor was functioning properly. While
in REACH state, the device takes no special action as packets are sent.
• Stale. More than ReachableTime milliseconds have elapsed since the last positive
confirmation was received that the forward path was functioning properly. While in
STALE state, the device takes no action until a packet is sent.
• Delay. More than ReachableTime milliseconds have elapsed since the last positive
confirmation was received that the forward path was functioning properly. A packet
was sent within the last DELAY_FIRST_PROBE_TIME seconds. If no reachability
confirmation is received within DELAY_FIRST_PROBE_TIME seconds of entering
the DELAY state, send a neighbor solicitation message and change the state to
PROBE.
• Probe. A reachability confirmation is actively sought by resending neighbor
solicitation messages every RetransTimer milliseconds until a reachability
confirmation is received.
• Unknown. The switch cannot determine the state of the cache entry.
Last Updated. Time since the address was confirmed to be reachable.
Field Description

NETGEAR GS748T Specifications

General

Basic switching RJ-45 Ethernet ports quantity	48
MAC address table	16000 entries
Packet buffer memory	1.632 MB
Maximum data transfer rate	1 Gbit/s
Latency	20 µs
I/O ports	48 RJ-45 connectors for 10BASE-T, 100BASE-TX, and 1000BASE-T (Auto Uplink on all ports) 4 SFP slots for fiber Gigabit Ethernet modules
Dimensions (WxDxH)	440 x 260 x 43 mm
Power requirements	100-240VAC 50/60 Hz
Networking features	10BASE-T, 100BASE-TX, 1000BASE-T
Connectivity technology	Wired
Full duplex	Yes
Networking standards	IEEE 802.3x
Minimum system requirements	Category 5 network cables Network card for each PC Network software (e.g., Windows)
Mean time between failures (MTBF)	69930 h
Safety	UL listed (UL 1950)/cUL, IEC950/EN60950
LED indicators	Link, Power
Power consumption (typical)	70 W
Storage temperature (T-T)	-10 - 70 °C
Operating temperature (T-T)	0 - 40 °C
Operating relative humidity (H-H)	10 - 90 %

Weight and Dimensions

Weight	4000 g