3Com 520 - Manual (Page 57)

Bridging and Routing Concepts A-3
local LAN because it does not recognize the
destination station as local. However, if the
destination device is on the local LAN, once it replies
to the original source station, its own source address
is part of the data frame and it is learned by the
bridge and added to the address table.
By operating in this way, the amount of data
forwarded by the bridge is kept to a minimum.
Traffic that is for devices on the attached LAN is
rarely forwarded over the bridge.
A bridge can be configured to forget or age a
station’s address after a period of inactivity, a facility
which is used to ensure that stations which are no
longer attached to the LAN, do not remain in the
bridge’s address table, using up space that may be
required for other stations’ addresses.
Some bridges allow address information to be
manually configured into the bridge, provided the
automatic learning facility is turned off, although this
will not normally prove necessary unless specific
traffic filtering is required.
You can also configure a number of other features
to improve the performance and operation of the
OfficeConnect Remote. These include sophisticated
frame filtering techniques so that only certain types
of frame, or those associated with particular work
groups, are passed between specific segments.
Bridging Between Remote Sites
The OfficeConnect Remote is able to send frames
between LANs that may be separated by
considerable physical distances. It achieves this by
making use of Wide Area Network (WAN) links. WANs
can be established by using either digital leased lines
or ISDN and are usually operated by telephone
companies (PTTs) or other service providers.
Figure A-1 shows two LAN segments, A and B, which
are connected by a pair of OfficeConnect Remote
units, 1 and 2. The type of link between the two
depends on the WAN services available at each of
the remote bridge locations, and the price the
network administrator is willing to pay for those
services.
Rc.bk : RCAPPA.FRM Page 3 Thursday, July 10, 1997 9:53 AM