Black Box LH8050A, Инструкция по установке и эксплуатации

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Black Box Mixed-Media Fiber Hubs Installation and User Guide (4/99)
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.
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Figure 4.2 : Filtering vs. Forwarding in Dual Speed LH8050A
Packet
Source Destination Address Table Filter/Forward
Source Address Address Maintenance Action
10 Mbps Not in table Not in table Add source to table Forward
10 Mbps Not in table In table Add source to table Filter
10 Mbps In table Not in table None Forward
10 Mbps In table In table None Filter
100Mbps Not in table Not in table Add source to table Forward
100Mbps Not in table In table Add source to table Filter
100Mbps In table Not in table None Forward
100Mbps In table In table None Filter
Table 4.2: LH8050A Dual-Speed Hub Functionality
1. Address Learning (Address Table Maintenance)
The Black Box LH8050A bridge module is a state machine design which has a total
address table capacity of 8K addresses. With a large address table, an LH8050A can serve the
needs of a medium-sized to large network. Table 4.2 shows what filter / forward action the
LH8050A will take in each packet-processing situation, and when a new node address will be
added to the internal Address Table. When a new node-address packet comes into a port for the
first time, then the new source address is “learned” at the same time that the packet is
forwarded. After learning, subsequent packets from the same node address are routinely
Bridge Module
100 Mb Traffic
100Mb Domain : 100Mb packets are
filtered when the destination address is
in the 100Mb domain address table.
100Mb Domain : 100Mb packets are
forwarded when the destination address is
NOT in the 100Mb domain address table.
10 Mb Domain 100 Mb Domain
10Mb Domain : 10Mb packets are
forwarded when the destination addresse is
NOT in the 10Mb domain address table.
10Mb Domain : 10Mb packets are
filtered when the destination address is
in the 10Mb domain address table.
10 Mb Traffic
10 BUS 100
10 BUS 100