3Com 4007, Implementation Manual, Page: 410 / 684

410 C
HAPTER
17: V
IRTUAL
R
OUTER
R
EDUNDANCY
P
ROTOCOL
(VRRP)
Spanning Tree Considerations
To prevent the links from going into blocking mode on the External
Switch side, you must:
■
Remove the BA1 and BA2 front panel ports in the Protocol VLAN from
the Default VLAN.
■
Set the Spanning Tree Protocol (STP) state for these ports equal to
Remove.
There is no Spanning Tree loop for the following reasons:
■
The Layer 3 front panel port drops any non-IP frames received from
the external switch.
■
The Layer 3 backplane port forwards only routing traffic to the BA1
and BA2 front panel port.
End Station Configuration
The backbone Layer 2 modules are populated with departmental end
stations on different subnetworks:
■
The backplane port of BA2 is configured with a single Protocol (IP)
VLAN, with multiple IP interfaces.
■
The backplane port of the BA2 is the default gateway for each
departmental subnetwork end station.
■
The backplane port of the BA2 functions as a one-armed router for
traffic between departmental end stations on Layer 2 modules.
The External Switch is populated with departmental end stations on
different subnetworks.
■
The front panel port of BA2 is configured with a single Protocol (IP)
VLAN, with multiple IP interfaces.
■
The front panel port of the BA2 is the default gateway for each
departmental subnetwork end station.
■
The front panel port of the BA2 functions as a one-armed-router for
traffic between departmental end stations on the external switch.
Traffic between end stations on the Backbone Switch 4007 Layer 2
module(s) and end stations on the External Switch is routed between the
BA2 backplane and front panel router ports.