ZyXEL Communications MGS-3712, User Manual

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Chapter 3 Hardware Overview
MGS-3712/MGS-3012F User’s Guide
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3.1.2 Gigabit Ethernet Ports
The Switch has 1000Base-T auto-negotiating, auto-crossover Ethernet ports. In 10/100/1000
Mbps Fast Ethernet, the speed can be 10 Mbps, 100 Mbps or 1000 Mbps and the duplex mode
can be half duplex or full duplex.
An auto-negotiating port can detect and adjust to the optimum Ethernet speed (10/100/1000
Mbps) and duplex mode (full duplex or half duplex) of the connected device.
An auto-crossover (auto-MDI/MDI-X) port automatically works with a straight-through or
crossover Ethernet cable.
Four of the 1000Base-T Ethernet ports are paired with a mini-GBIC slot to create a dual
personality interface. The Switch uses up to one connection for each mini-GBIC and
1000Base-T Ethernet pair. The mini-GBIC slots have priority over the Gigabit ports. This
means that if a mini-GBIC slot and the corresponding GbE port are connected at the same
time, the GbE port will be disabled.
When auto-negotiation is turned on, a Ethernet port negotiates with the peer automatically to
determine the connection speed and duplex mode. If the peer Ethernet port does not support
auto-negotiation or turns off this feature, the Switch determines the connection speed by
detecting the signal on the cable and using half duplex mode. When the Switch’s auto-
negotiation is turned off, an Ethernet port uses the pre-configured speed and duplex mode
when making a connection, thus requiring you to make sure that the settings of the peer
Ethernet port are the same in order to connect.
3.1.2.1 Default Ethernet Negotiation Settings
The factory default negotiation settings for the Gigabit ports on the Switch are:
• Speed: Auto
• Duplex: Auto
• Flow control: Off
• Link Aggregation: Disabled
3.1.2.2 Auto-crossover
All ports are auto-crossover, that is auto-MDIX ports (Media Dependent Interface Crossover),
so you may use either a straight-through Ethernet cable or crossover Ethernet cable for all
Gigabit port connections. Auto-crossover ports automatically sense whether they need to
function as crossover or straight ports, so crossover cables can connect both computers and
switches/hubs.
3.1.3 Mini-GBIC Slots
These are slots for mini-GBIC (Gigabit Interface Converter) transceivers. A transceiver is a
single unit that houses a transmitter and a receiver. The Switch does not come with
transceivers. You must use transceivers that comply with the Small Form-factor Pluggable
(SFP) Transceiver MultiSource Agreement (MSA). See the SFF committee’s INF-8074i
specification Rev 1.0 for details.
You can change transceivers while the Switch is operating. You can use different transceivers
to connect to Ethernet switches with different types of fiber-optic or even copper cable
connectors.