CCNA 新版（英文）D20S03L01.pps

© 2002, Cisco Systems, Inc. All rights reserved.
Configuring Catalyst Switch Operations
Module 3
Objectives
pleting this module, you will be able to:
Explain how bridging and switching operates
Explain the purpose and operations of the Spanning-Tree Protocol
Verify the default configuration of the device, given a functioning access layer switch
Build a functional access switch configuration to support the work operational parameters, given work design
Execute an add, move, or change on an access layer switch, given a work requirement
© 2002, Cisco Systems, Inc. All rights reserved.
4
Basic Layer 2 Switching and Bridging Functions
Objectives
pleting this lesson, you will be able to:
Describe Layer 2 switching and bridging operations and modes
Describe how LAN switches use and populate the MAC address table
Address learning
Forward/filter decision
Loop avoidance
Switches and Bridges
Cut-Through
Switch checks destination address and immediately begins forwarding frame.
Fragment-Free
Switch checks the first 64 bytes, then immediately begins forwarding frame.
Store and plete frame is received and checked before forwarding.
Transmitting Frames
MAC Address Table
Initial MAC address table is empty.
Learning Addresses
Station A sends a frame to station C.
Switch caches the MAC address of station A to port E0 by learning the source address of data frames.
The frame from station A to station C is flooded out to all ports except port E0 (unknown unicasts are flooded).
Learning Addresses (Cont.)
Station D sends a frame to station C.
Switch caches the MAC address of station D to port E3 by learning the source address of data frames.
The frame from station D to station C is flooded out to all ports except port E3 (unknown unicasts are flooded).