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EDS-508 Hardware Installation Guide
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 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.
MOXA EDS-508 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
MOXA EDS-508 has an address table that can hold up to 2000 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, MOXA EDS-508 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 MOXA EDS-508'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. MOXA EtherDevice 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 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.
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