Cisco Catalyst 3750-E User Manual

48-3
Catalyst 3750-E and 3560-E Switch Software Configuration Guide
OL-9775-08
Chapter 48 Configuring Fallback Bridging
Configuring Fallback Bridging
Fallback Bridging and Switch Stacks
When the stack master fails, a stack member becomes the new stack master by using the election process
described in Chapter 5, “Managing Switch Stacks.” The new stack master creates new VLAN-bridge
spanning-tree instance, which temporarily puts the spanning-tree ports used for fallback bridging into a
n
onforwarding state. A momentary traffic disruption occurs until the spanning-tree states transition to
the forwarding state. All MAC addresses must be relearned in the bridge group.
Note If a stack master running the IP services feature set fails and if the newly elected stack master is running
the IP base feature set, the switch stack loses its fallback bridging capability.
If stacks merge or if a switch is added to the stack, any new VLANs that are part of a bridge group and
become active are included in the VLAN-bridge STP.
When a stack member fails, the addresses learned from this member are deleted from the bridge group
M
AC address table.
For more information about switch stacks, see Ch
apter 5, “Managing Switch Stacks.”
Configuring Fallback Bridging
• Default Fallback Bridging Configuration, page 48-3
• Fallback Bridging Configuration Guidelines, page 48-4
• Creating a Bridge Group, page 48-4 (required)
• Adjusting Spanning-Tree Parameters, page 48-5 (optional)
Default Fallback Bridging Configuration
Ta b l e 48-1 Default Fallback Bridging Configuration
Feature Default Setting
Bridge groups None are defined or assigned to a port. No
V
LAN-bridge STP is defined.
Switch forwards frames for stations that it has
d
ynamically learned
Enabled.
Spanning tree parameters:
• Switch priority
• Port priority
• Port path cost
• Hello BPDU interval
• Forward-delay interval
• Maximum idle interval
• 32768.
• 128.
• 10 Mb/s: 100.
100 Mb/s: 19.
1000 Mb/s: 4.
• 2 seconds.
• 20 seconds.
• 30 seconds.

Cisco Catalyst 3750-E Specifications

General

Series	Catalyst 3750-E
Switching Capacity	32 Gbps
Stacking Bandwidth	32 Gbps
StackWise Plus	Yes
Layer Support	Layer 3
MAC Address Table Size	12, 000 entries
RAM	256 MB
Flash Memory	64 MB
Memory	256 MB DRAM, 64 MB Flash
Operating Temperature	32 to 113°F (0 to 45°C)
Ports	48 10/100/1000 Ethernet ports
Form Factor	Rack-mountable
Jumbo Frame Support	Yes
Input Voltage	100 to 240 VAC
Storage Temperature	-25 to 70 °C
Relative Humidity	10 to 90% non-condensing