文档介绍：Chapter 9
交换机原理及配置
网络系统工程师交换机原理及配置
地址（MAC）学****br/>转发/筛选
环路避免
Switch 的三个功能
网络系统工程师交换机原理及配置
Switches 地址学****br/>初始 MAC 地址表为空
学****源地址
MAC address table
E0
E1
E2
E3
A
B
C
D
网络系统工程师交换机原理及配置
Switches地址学****br/>Station A sends a frame to Station C
Switch caches station A MAC address 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)
MAC address table
E0:
E0
E1
E2
E3
D
C
B
A
网络系统工程师交换机原理及配置
Switches地址学****br/>Station D sends a frame to station C
Switch caches station D MAC address 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)
MAC address table
E0:
E3:
E0
E1
E2
E3
D
C
A
B
网络系统工程师交换机原理及配置
Switches 转发/过滤
Station A sends a frame to station C
Destination is known, frame is not flooded
E0:
E2:
E1:
E3:
E0
E1
E2
E3
X
X
D
C
A
B
MAC address table
网络系统工程师交换机原理及配置
Station D sends a broadcast or multicast frame
Broadcast and multicast frames are flooded to all ports other than the originating port
E0
E1
E2
E3
D
C
A
B
E0:
E2:
E1:
E3:
MAC address table
广播与多播Frame
网络系统工程师交换机原理及配置
冗余路径
冗余路径消除了单故障点
冗余路径的不利后果：
广播风暴, 多个Frame副本, MAC地址表不稳定
Segment 1
Segment 2
Server/host X
Router Y
网络系统工程师交换机原理及配置
Segment 1
Segment 2
Server/host X
Router Y
Broadcast
Switch A
Switch B
Host