GarrettCom Magnum DS80 Installation And User Manual page 20

Magnum DS80 Dual-Speed Personal Hub
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.
10Mb Domain : 10Mbps packets are
forwarded when the destination addresse is
NOT in the 10Mb domain address table.
10Mbps Domain : 10Mbps packets are
filtered when the destination address is
in the 10Mbps domain address table.
10 Mbps Domain
10 Mbps Traffic
Figure 4.1 : Filtering and Forwarding in DS80 Personal Hubs
Packet Source
Source Address
10 Mbps Not in table
10Mbps Not in table
10Mbps In table
10Mbps In table
100Mbps Not in table
100Mbps Not in table
100Mbps In table
100Mbps In table
2.
The Magnum DS80 bridge chip is a state machine design which has a total
address table capacity of 1.8K addresses. With a large address table, a Magnum DS80
can serve the needs of a medium-sized to large network. Table 4.1 shows what filter /
forward action the Magnum DS80 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
GARRETT
Magnum DS80
Bridge I.C
Destination
Address
Not in table
In table
Not in table
In table
Not in table
In table
Not in table
In table
Table 4.1: DS80 Dual-Speed Hub Functionality
Address Learning (Address Table Maintenance)
Installation and User Guide (11/98)
100Mbps Domain : 100Mbps packets are
forwarded when the destination address is
NOT in the 100Mb domain address table.
100Mbps Domain : 100Mbps packets are
filtered when the destination address is
in the 100Mbps domain address table.
Address Table
Maintenance
Add source to table
Add source to table
None
None
Add source to table
Add source to table
None
None
16
100 Mbps Domain
100 Mbps Traffic
Filter/Forward
Action
Forward
Filter
Forward
Filter
Forward
Filter
Forward
Filter