3Com CoreBuilder 3500, Implementation Manual

Page: 97 / 592

Key Concepts 97
Dual Homing When the operation of a dual attachment node is crucial to your
network, a configuration called
dual homing can provide added reliability.
Using dual homing you can determine a station’s operation by setting the
appropriate configuration policy. You can configure the dual-homed
station with both links active or with one link active and one connection
withheld as a backup. The backup connection becomes active only if the
primary link fails. See Figure 17.
Figure 17 Dual Homing
FDDI Stations Each FDDI station has one Station Management (SMT) entity to provide
connection management, ring management, and operational
management to the FDDI network. SMT specifies a set of services and
signaling mechanisms that are dedicated to FDDI network management.
It manages those services of each station on the FDDI network that are
specific to the Physical Layer and the MAC portion of the Data Link Layer.
The goal of SMT is to completely define shared medium-management
services to guarantee the interoperability of FDDI network equipment
from multiple vendors.
Secondary
system
Link set by
configuration policy
Dual-homed
node
DAS
Primary link
Primary
system
Duplex
fiber
cable FDDI
dual
ring
M
A
B
M
A
B
A
B
M
M