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Auto MDI/MDI-X Connection
The Auto MDI/MDI-X function allows users to connect the Ethernet Switch's
10/100BaseTX ports to any kind of Ethernet device, without needing to pay
attention to the type of Ethernet cable being used for the connection. This means
that you can use either a straight-through cable or cross-over cable to connect the
Ethernet Switch to Ethernet devices.
Dual Speed Functionality and Switching
The Ethernet Switch's 10/100 Mbps switched RJ45 port auto negotiates with the
connected device for the fastest data transmission rate supported by both devices.
All models of Ethernet Switch are plug-and-play devices, so that software
configuration is not required at installation, or during maintenance. The half/full
duplex mode for the switched RJ45 ports is user dependent and changes (by
auto-negotiation) to full or half duplex, depending on which transmission speed
is supported by the attached device.
Switching, Filtering, and Forwarding
Each time a packet arrives at one of the switched ports, a decision is made to
either filter or forward the packet. Packets with source and destination addresses
belonging to the same port segment will be filtered, constraining those packets to
one port, and relieving the rest of the network from the need to process them. A
packet with destination address on another port segment will be forwarded to the
appropriate port, and will not be sent to ports where it is not needed. Packets that
are used in maintaining the operation of the network (such as the occasional
multi-cast packet) are forwarded to all ports. The Ethernet Switch operates in the
store-and-forward switching mode, which eliminates bad packets and enables
peak performance to be achieved when there is heavy traffic on the network.
Switching and Address Learning
The Ethernet Switch has an address table that can hold up to 1024 addresses,
which makes it suitable for use with large networks. The address tables are
self-learning, so that as nodes are added or removed, or moved from one
segment to another, the Ethernet Switch automatically keeps up with new node
locations. An address-aging algorithm causes the least-used addresses to be
deleted in favor of newer, more frequently used addresses. To reset the address
buffer, power down the unit and then power it back up.
Auto-Negotiation and Speed Sensing
All of the Ethernet Switch's RJ45 Ethernet ports independently support
auto-negotiation for speeds in the 10BaseT and 100BaseTX modes, with
operation according to the IEEE 802.3u standard. This means that some nodes
could be operating at 10 Mbps, while at the same time, other nodes are operating
at 100 Mbps. Auto-negotiation takes place when an RJ45 cable connection is
made, and then each time a LINK is enabled. The Ethernet Switch advertises its
capability for using either 10 Mbps or 100 Mbps transmission speeds, with the
device at the other end of the cable expected to advertise in a similar manner.
Depending on what type of device is connected, this will result in agreement to
operate at a speed of either 10 Mbps or 100 Mbps. If an Ethernet Switch RJ45
Ethernet port is connected to a non-negotiating device, it will default to 10 Mbps
speed and half-duplex mode, as required by the IEEE 802.3u standard.
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