GarrettCom 1008 - Manual (Page 37)

Magnum 1000 Workgroup Hubs Installation and User Guide (04/02)
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there. This happens when a node first sends Figure 4.2c: External Packet
Forwarded
a packet upon bridge initialization.
Note, therefore, that the address
table learns only internal addresses, i.e.,
those connected via the inside of the local
Magnum 1000, a number typically well
under the 256 table addresses size. Should
the table become full, the BPM will clear all
entries in the table by reinitializing itself.
When
an external packet’s source address
is in the address table, it is purged. Figure 4.2d: External Packet Filtered
This can occur if a node has physically moved to a different location.
A summary of the filtering, forwarding, and address table
maintenance performed by the BPMs is shown in Table 4.2.
Table 4.2: BPM Functionality
Packet Source Destination Address Table Filter/Forward
Source Address Address Maintenance Action
Internal Not in table Not in table Add source to table Forward
Internal Not in table In table Add source to table Filter
Internal In table Not in table Nothing Forward
Internal In table In table Nothing Filter
External Not in table Not in table Nothing Filter
External Not in table In table Nothing Forward
External In table Not in table Purge source from table Filter
External In table In table Purge source from table Forward
2. Throughput Increase: By using a BPM to isolate a user group segment
having significant local traffic, it is possible to increase overall network
throughput. For example, a segment containing a group of workstations and
servers may have heavy local traffic, but only a small amount of traffic that is
External packets
are filtered when
the destination is
NOT IN the
address table.