3com 3CDSG10PWR Guia Do Utilizador
216
A
PPENDIX
B: D
EVICE
S
PECIFICATIONS
AND
F
EATURES
Electrical
Switch Features
This section describes the device features. The system supports the
following features:
following features:
Line Frequency
50/60 Hz
Input Voltage
100–240 Vac (auto range)
Current Rating
2 Amp (Max)
Maximum Power
Consumption
Consumption
358.4 BTU/hr (114 Watts)
Max Heat Dissipation
79 BTU/hr
Table 9 Features of the OfficeConnect Managed Gigabit PoE Switch
Feature
Description
Auto Negotiation
The purpose of auto negotiation is to allow a device to advertise modes of
operation. The auto negotiation function provides the means to exchange
information between two devices that share a point-to-point link
segment, and to automatically configure both devices to take maximum
advantage of their abilities.
operation. The auto negotiation function provides the means to exchange
information between two devices that share a point-to-point link
segment, and to automatically configure both devices to take maximum
advantage of their abilities.
Auto negotiation is performed totally within the physical layers during link
initiation, without any additional overhead to either the MAC or higher
protocol layers. Auto negotiation allows the ports to do the following:
initiation, without any additional overhead to either the MAC or higher
protocol layers. Auto negotiation allows the ports to do the following:
■
Advertise their abilities
■
Acknowledge receipt and understanding of the common modes of
operation that both devices share
operation that both devices share
■
Reject the use of operational modes that are not shared by both
devices
devices
■
Configure each port for the highest-level operational mode that both
ports can support
ports can support
Automatic MAC Addresses Aging
MAC addresses from which no traffic is received for a given period are
aged out. This prevents the Bridging Table from overflowing.
aged out. This prevents the Bridging Table from overflowing.
Back Pressure
On half duplex links, the receiver may employ back pressure (i.e. occupy
the link so it is unavailable for additional traffic), to temporarily prevent
the sender from transmitting additional traffic. This is used to prevent
buffer overflows.
the link so it is unavailable for additional traffic), to temporarily prevent
the sender from transmitting additional traffic. This is used to prevent
buffer overflows.
Address Resolution Protocol (ARP)
ARP converts between IP addresses and MAC (i.e., hardware) addresses.
ARP is used to locate the MAC address corresponding to a given IP
address. This allows the switch to use IP addresses for routing decisions
and the corresponding MAC addresses to forward packets from one hop
to the next.
ARP is used to locate the MAC address corresponding to a given IP
address. This allows the switch to use IP addresses for routing decisions
and the corresponding MAC addresses to forward packets from one hop
to the next.
Class Of Service (CoS)
Provide traffic belonging to a group preferential service (in terms of
allocation of system resources), possibly at the expense of other traffic.
allocation of system resources), possibly at the expense of other traffic.