User Manual

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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 EDS 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 EDS 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 EDS 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 EDS’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 EDS
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 EDS 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.
Specifications
Technology
Standards
IEEE 802.3 for 10BaseT,
IEEE 802.3u for 100BaseT(X) and 100BaseFX,
IEEE 802.3x for Flow Control
Processing Type
Store and Forward
Flow Control
IEEE 802.3x flow control, back pressure flow
control
Interface
RJ45 Ports 10/100BaseT(X) auto negotiation speed, F/H
duplex mode, and auto MDI/MDI-X
connection
Fiber Ports
100BaseFX ports (SC/ST connector,
multi/single-mode)