Specifications

Chapter 2: Introduction
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The LPH240A(PoE) Switch provides edge access Ethernet
ports in a convenient and compact package. For fiber connectivity of
additional non-PoE ports, simply use port#1 and 2 (two RJ-45 or 100 Mb
fiber ports with LLL feature) to meet the Fiber and copper 10 or 100 Mb
requirements. All LPH240A Power Source Edge Switch models come
with two (2) sets of LED indicators. One set is mounted in the end
adjacent to three of the RJ-45 ports for easy viewing when the unit is
mounted in a rack mount tray.
The LPH240A Power Source Switch requires a heavy-duty
power supply of -48VDC 1.4Amps (66 watts total consumption) to provide
13-15w power on each port to the PoE unit. Also available with standard
AC input utilizing a IEC 320 male recessed connector with internal AC/DC
power supply.
2.3 Frame Buffering and Latency
The LPH240A-Series PoE Edge Switches are store-and-
forward switches. Each frame (or packet) is loaded into the Switch’s
memory and inspected before forwarding can occur. This technique
ensures that all forwarded frames are of a valid length and have the
correct CRC, i.e. they are good packets. This eliminates propagation of
bad packets, enabling all of the available bandwidth to be used for valid
information.
While other switching technologies such as "cut-through" or
"express" impose minimal frame latency, they will also permit bad frames
to propagate to the Ethernet network. The "cut-through" technique
permits collision fragment frames, which are a result of late collisions, to
be forwarded--which add to the network traffic.