3Com 3C780 User Guide - Page 74

Dual Homing

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3-6 Configuring the Hub Dual Homing Dual homing (DH) configuration provides two attachments to the FDDI network. One of them functions as a backup link if the primary link fails. This type of attachment is especially useful for connecting to mission-critical devices. Figure 3-5 illustrates valid connections for a dual homed hub. DAC DAC Dual homed backup link Dual homed hub A B Primary link Server on FDDI Workstation on FDDI Host on FDDI Figure 3-5. Dual Homing Connections Ports A and B are both connected to the primary ring. Following the B precedence rule, the B port always takes precedence and becomes the primary link. If the connection to the B port fails, the A port serves as the backup and automatically becomes the primary port. The dual homed hub shown in Figure 3-5 is actually a dual attachment hub, but only one port is active at a time.

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3-6
Configuring the Hub
Dual Homing
Dual homing (DH) configuration provides two attachments to the FDDI
network.
One of them functions as a backup link if the primary link fails.
This
type of attachment is especially useful for connecting to mission-critical
devices.
Figure 3-5 illustrates valid connections for a dual homed hub.
DAC
DAC
Dual
homed
backup
link
Primary
link
A
B
Dual homed hub
Server on FDDI
Host on FDDI
Workstation on FDDI
Figure 3-5.
Dual Homing Connections
Ports A and B are both connected to the primary ring.
Following the B
precedence rule, the B port always takes precedence and becomes the primary
link.
If the connection to the B port fails, the A port serves as the backup and
automatically becomes the primary port.
The dual homed hub shown in Figure
3-5 is actually a dual attachment hub, but only one port is active at a time.