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Magnum DS80F & DS80C Dual-speed Stackable Hubs Installation and User Guide (12/01)
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4.0 OPERATION - the function and operation of the Magnum DS80F and DS80C hubs.
4.1 Dual-speed functionality, and switching
The Magnum DS80F and DS80C Personal Hubs provides two N-way
switched ports (one of which may be 100Mb fiber) and six dual-speed half-duplex ports. The
architecture supports a few users at 10/100Mbps, and a high speed up-link and/or server port
typically at 100Mbps full-duplex.
The user ports #3 to 8 are half-duplex auto-sensing for speed. (See section 2.2). When
the connected device is 10Mbps, the DS80F obeys all the rules of 10Mbps Ethernet
configurations, (4 repeaters, 2Km fiber distance half-duplex etc.). The 10Mbps users share a
10Mbps traffic domain, and can “communicate with” 100Mbps users and the switched ports
through a
switch to the 100Mbps domain. Similarly, the 100Mbps traffic on ports #3 to 8 obeys the rules
of 100Mbps Ethernet, and shares a 100Mbps collision domain.
Magnum DS80F and DS80C units are plug-and-play devices. There is no software
configuring to be done at installation or for maintenance. The only hardware configuration
settings are user options for UP-LINK on RJ-45 port #1 SW. Half / Full duplex mode selection
for the switched ports can be done through a switch accessed from the front of the unit. The
internal functions of both are described below.
Switching, Filtering and Forwarding
Each time a packet arrives on one of the switched ports, the decision is taken to either
filter or to forward the packet. Packets whose source and destination addresses on the same port
segment will be filtered, constraining them to one port and relieving the rest of the network from
processing them. A packet whose destination address is 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 needed for maintaining the operation of the network (such as occasional multi-cast
packets) are forwarded to all ports.
The Magnum DS80F and DS80C Personal Hubs operate 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, Address Learning
The Magnum DS80F and DS80C units have address table capacity of 16K node