Bay Networks Marlin, Reference Manual

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T
UTORIAL
2-7
2.4 R
EMOTE
B
RIDGES
Local bridges can connect LAN segments which are physically close to
each other (not more than a few metres apart). Remote bridges do much the
same job as local bridges, but can carry data between LANs that may be
separated by great physical distances. They use wide area links and
networks such as analogue and digital leased lines, X.25 packet switching,
Frame Relay, ISDN.
This section describes the aspects of remote bridging which are different
from or in addition to those described under L
OCAL
B
RIDGES
.
Figure 2-3 shows two LAN segments (LAN A, LAN B) connected by two
remote bridges (Bridge 1, Bridge 2). The type of link between the segments
depends on the wide area network services available at each of the remote
bridge locations and how much the network administrator is willing to pay
for those services.
Bridge 1
Bridge 2
LAN A
LAN B
Figure 2-3 Remote Bridging
Each remote bridge sees the link to its partner bridge, the partner bridge
itself and the remote LAN as one LAN segment which usually operates at a
slower speed (i.e. the speed of the link) than its own locally connected
LAN. When seen in this way, the description given in the section on local
bridge operation describes exactly how each remote bridge in Figure 2-3
operates.
The main function of the remote bridge is to send all frames intended for the
remote LAN as fast, efficiently and reliably as possible, given the type of
link connecting it to its partner.