16- and 36-Port Ethernet Switch Module for Cisco 2600 Series, Cisco 3600 Series, and Cisco 3700 Series
Feature Overview
18
Cisco IOS Release 12.2(2)XT, 12.2(8)T, and 12.2(15)ZJ
Learning State
A Layer 2 interface in the learning state prepares to participate in frame forwarding. The Layer 2
interface enters the learning state from the listening state.
Figure 7
shows a Layer 2 interface in the
learning state.
Figure 7
Interface 2 in Learning State
A Layer 2 interface in the learning state performs as follows:
•
Discards frames received from the attached segment.
•
Discards frames switched from another interface for forwarding.
•
Incorporates end station location into its address database.
•
Receives BPDUs and directs them to the system module.
•
Receives, processes, and transmits BPDUs received from the system module.
•
Receives and responds to network management messages.
Filtering
database
Frame
forwarding
System
module
Port 1
BPDUs
All segment
frames
BPDU and network
management frames
All segment
frames
Forwarding
Learning
BPDUs
Station
addresses
Network
management
and data frames
Port 2
S5694
Network
management
frames
Station
addresses
Data
frames