Configuring and Monitoring Port Security

MAC Lockdown

Internal

Network

PROBLEM: If this link fails,

traffic to Server A will not use Server A the backup path via Switch 3

 

 

 

 

Switch 3

 

 

 

 

 

 

 

 

 

 

 

 

 

Switch 4

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Server A is locked down to Switch 1, Uplink 2

Switch 1

 

Switch 2

 

 

 

External

Network

M i x e d U s e r s

Figure 13-11. Connectivity Problems Using MAC Lockdown with Multiple Paths

The resultant connectivity issues would prevent you from locking down Server A to Switch 1. And when you remove the MAC Lockdown from Switch 1 (to prevent broadcast storms or other connectivity issues), you then open the network to security problems. The use of MAC Lockdown as shown in the above figure would defeat the purpose of using MSTP or having an alternate path.

Technologies such as MSTP or “meshing” are primarily intended for an inter­ nal campus network environment in which all users are trusted. MSTP and “meshing” do not work well with MAC Lockdown.

If you deploy MAC Lockdown as shown in the Model Topology in figure 13-10(page 13-27),you should have no problems with either security or connectiv­ ity.

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