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Magnum 8000X Mixed-Media Fiber Hubs Installation and User Guide (05/ 02)
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4.0 Operation
The operation of the Magnum 8000X is described in this section.
4.1 Repeater Functionality
The Magnum 8000X operates as a Mixed-Media Ethernet Hub to support
multiple port segments within two (10 and 100Mbps) collision domains. The
following describes the basic functionality of the Magnum 8000X Fiber Hub.
1. Repeater Functions: Each front port operates in conjunction with the
controller functions of the 8000X chassis as a fully compliant Ethernet repeater.
The entire hub (or a stack of multiple units) counts as one Dual-Speed repeater.
2. Collisions: When a collision is detected at a port other than the original
receiving port, it generates a jam pattern to the other ports in that domain.
When a collision signal is detected at a receiving port, it generates a jam pattern
to the other ports. The sequence of jam signals depends on the sequence and
location of collisions.
3. Partitioning and Re-connection: An Magnum 8000X will automatically
disconnect (partition) any segment (port) when 64 consecutive collisions occur
or after 6.5 ms of continuous transmissions. Network integrity is checked every
800 ms and segment (port) reconnection occurs after a 512-bit packet is
transmitted without error.
4. Link Status: The Magnum 8000X PMs indicate link integrity for fiber
optic and twisted pair segments. LINK is normally lit. Broken cables or a
loss of power at any point in such segments will turn off the LINK LED.
4.2 Dual-Speed Functionality
The Magnum 8000X handles the two different traffic domains separately . The
8000X provides switched (bridged) connectivity between the Ethernet (10 Mbps) and
Fast Ethernet (100Mbps) domains. It joins the two network domains for unified
operation, and filters/ forwards packets in both directions to maximize bandwidth
utilization and performance. Magnum 8000Xs are hardware plug-and-play devices.
There is no software set-up to be done at installation or for maintenance. The functions
of the Magnum 8000X are described in this manual.
Each time a packet is received on one domain of the bridge module, the decision is
taken to either to filter or forward the packet. Errored packets are always filtered. For
good packets, the filter and forward decisions are made based on the destination address
contained in each packet. If the destination address is on the same domain from which
the packet originated, then it is filtered and not forwarded to the other domain. If the
destination address is not found to be a match in the address table for the originating
domain, then it is forwarded to the other domain. If it is a new node address coming in
which the switch did not previously know about, it “learns” the new address and puts it
in the correct port address table. See “Address Learning” for more details. This
diagram below shows the filter / forward logic for both domains.