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Switching, Filtering, and Forwarding
Each time a packet arrives at one of the switched ports, a decision is made
either to filter or to 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 the other 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.
EDS-208 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
EDS-208 has an address table that can hold up to 1,000 node 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, EDS-208 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 EDS-208’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 a “live” RJ45 cable is connected to the
switch, and then each time a LINK is enabled. EDS-208 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 similarly advertise. 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-208 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 IEEE802.3, 802.3u, 802.3x
Processing Type Store and Forward, with IEEE802.3x full duplex,
non-blocking flow control
Address Table Size 1,000 uni-cast addresses
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)
LED Indicators Power, 10/100 M (TP port), 100 M (FX port)