Alcatel Carrier Internetworking Solutions Switch/Router Manuale Utente

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Network 3

Network 2

Network 3

MAC

 address = 

B

Network 2

MAC

 address = 

A

Interface for

Network 2

MAC

 address = 

X

Interface for

Network 3

MAC

 address = 

Y

➋

➍

Let’s say that the next transmission is a 

RIP

 update from the router interface for network 3.

The source of the 

RIP

 update is Network 3, 

MAC

 address Y. AutoTracker thus assigns 

MAC

address Y to 

VLAN

 3. 

MAC

 address Y is now assigned to both 

VLAN

 2 and 

VLAN

 3. 

The same situation can occur with 

MAC

 address X on the router interface for network 2.

Both router interfaces will be members of both 

VLAN

s and will transmit 

RIP

 updates to both. 

➌

The switch receives the frame from Net-
work 2, 

MAC

 address Y, forwards it to

its destination, Device B, and gives it to
AutoTracker to be learned. 

Per the policies, AutoTracker assigns the
frame’s source 

MAC, MAC

 address Y, to

VLAN

 2. The router interface for net-

work 3 is now a member of network 2!

The router receives the frame on the interface for Network 2 and
routes the frame to the interface for Network 3. To do this, the router
strips the 

MAC

 header from the frame and inserts the 

MAC

 address of

from Network 2, 

MAC

 address A

➊

Device A initiates a request to
route a frame to Device B. The
switch forwards the frame to the
router interface for Network 2.

from Network 2, 

MAC

 address Y

from Network 2, 

MAC

 address Y

its interface for Network 3. The
frame now specifies its source
as Network 2, 

MAC

 address Y.

T h i s   e x a m p l e   a s s u m e s   t h a t
AutoTracker has not yet learned
the 

MAC

 addresses of the router

interfaces for Networks 2 and 3.