
14-7
Catalyst 6500 Series Switch and Cisco 7600 Series Router Firewall Services Module Configuration Guide using ASDM
OL-20748-01
Chapter 14 Configuring Failover
Understanding Failover
If the entire switch fails, as well as the FWSM (such as in a power failure), then both the switch and the
FWSM fail over to their secondary units (
Figure 14-4
).
Figure 14-4
Switch Failure
Transparent Firewall Requirements
To avoid loops when you use failover in transparent mode, you must use switch software that supports
BPDU forwarding, and you must configure the FWSM to allow BPDUs. See the
“Switch Hardware and
Software Compatibility” section on page A-1
for switch software versions that allow BPDUs
automatically.
To allow BPDUs through the FWSM, configure an EtherType ACL and apply it to both interfaces
according to the
“Adding an EtherType Access List” section on page 13-9
.
Loops can occur if both modules are active at the same time, such as when both modules are discovering
the presence of the other module, or due to a bad failover link. Because the FWSMs bridge packets
between the same two VLANs, loops can occur when inside packets destined for the outside get
Failed
FWSM
VLAN 200
VLAN 100
VLAN 201
Mktg
Inside
Eng
Active
FWSM
Internet
VLAN 202
VLAN 203
Trunk
132922
Summary of Contents for 6500 - Catalyst Series 10 Gigabit EN Interface Module Expansion
Page 35: ...P A R T 1 Getting Started and General Information ...
Page 36: ......
Page 297: ...P A R T 2 Configuring the Security Policy ...
Page 298: ......
Page 521: ...P A R T 3 System Administration ...
Page 522: ......
Page 613: ...P A R T 4 Reference ...
Page 614: ......