Mini-Gbic Slots - ZyXEL Communications MGS-3712/MES-3728 User Manual

An auto-crossover (auto-MDI/MDI-X) port automatically works with a straight-
through or crossover Ethernet cable.
Two 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.
MES-3728 User's Guide
Chapter 3 Hardware Overview
35