Chapter 3
Optional Configurations
25
An Overview of Dual Homing
When two Sun GigabitEthernet adapters are installed in the same server, they can be
paired in a Dual Homing configuration. If traffic is not seen over the primary
adapter connection due to loss of the adapter, cable, switch port, or switch (where
the two adapters are attached to separate switches), the secondary adapter becomes
active. When it becomes active, the secondary adapter uses the MAC and IP address
originally assigned to the primary adapter. Sessions should be maintained, causing
minimum impact to the user.
The Dual Homing feature requires that Spanning Tree Protocol be enabled. Adapters
configured for Dual Homing allow Spanning Tree Protocol packets to pass between
them. This causes the Spanning Tree Protocol to detect a loop in the network, forcing
the switch port connected to one of the adapters to go into blocking mode. The
blocked adapter becomes the secondary.
If the primary connection becomes disabled for any reason, the Spanning Tree
Protocol will detect the loss of the loop, and will change the switch port connecting
the secondary adapter from blocking mode to forwarding mode.
▼
To Configure Dual Homing
To set up a Dual Homing configuration in a system with two adapters, where
adapter
etc/hostname.vge0
is primary and
etc/hostname.vge1
is secondary,
enter the following:
1. Enable Spanning Tree Protocol on the switch connected to your adapters.
Adapter #2 is blocked at switch port
Server
Switch
Both Connections Ready
Spanning Tree Loop Detected:
Adapter #1 is active
#1
#2
Adapter #2 is active
Server
Switch
Primary Connection Failed
Loop resolved:
Adapter #1 has dropped from loop
#1
#2
