Cisco NM-8B-U - HW ROUTERS L-M User Manual page 20

Feature Overview
Disabled State
A Layer 2 interface in the disabled state does not participate in frame forwarding or spanning tree, as
shown in
Figure 9
Station
addresses
Filtering
database
A disabled Layer 2 interface performs as follows:
• Discards frames received from the attached segment.
• Discards frames switched from another Layer 2 interface for forwarding.
• Does not incorporate end station location into its address database. (There is no learning, so there is
no address database update.)
• Does not receive BPDUs.
• Does not receive BPDUs for transmission from the system module.
MAC Address Allocation
The MAC address allocation manager has a pool of MAC addresses that are used as the bridge IDs for
the VLAN spanning trees. In
Table 3
Platform
Cisco 3640 or higher
Cisco 3620
Cisco 2600
Cisco IOS Release 12.2(2)XT, 12.2(8)T, and 12.2(15)ZJ
20
16- and 36-Port Ethernet Switch Module for Cisco 2600 Series, Cisco 3600 Series, and Cisco 3700 Series
Figure 9. A Layer 2 interface in the disabled state is virtually nonoperational.
Interface 2 in Disabled State
All segment
Forwarding
frames
Port 1
BPDUs
System
module
Data
frames
Port 2
Disabled All segment
frames
Table 3
Number of VLANs Allowed by Platform
Maximum number of VLANs allowed
64 VLANS
32 VLANs
32 VLANs
Network
management
and data frames
Frame
forwarding
Network
management
frames
you can view the number of VLANs allowed for each platform.