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Chapter 5. Advanced Cisco NAC Appliance ... > IP Telephony Best Practices for Out-...

IP Telephony Best Practices for Out-of-Band Mode

If your voice-facing NAC Appliance Server is running in OOB mode, your design becomes a little bit more complex. This makes sense given that with OOB mode you are controlling the actual switch port that the IP phone and its connected client are attached to. The basic rule of thumb is that if you will not have a client connecting to an IP phone, make sure that the phone’s switch port is still set to be controlled in NAC Appliance Manager. Use MAC address filters to identify and permit your IP phones. This practice ensures that rogue users cannot gain access by disconnecting an IP phone and plugging in a laptop. If your clients do connect directly to the IP phones, you should consider the following design recommendations:

  • Set your switch profiles to never bounce a switch port.

  • The MAC addresses of all IP phones must be added and maintained in NAC Appliance Manager’s Filter list.

  • If you use NAC Appliance in Layer 3 adjacency Out-of-Band mode, you must rely on the DHCP release and renew functionality built into the Clean Access Agent and web login applet.

  • If you configure NAC Appliance to change port VLANs dynamically, you must rely on the DHCP release and renew functionality built into the agent and applet to change the client’s IP address.

  • Use the certified timer in environments where the clients connect to the IP phone and not the switch port.

  • You must configure NAC Appliance and your switches to use the MAC Notification SNMP trap and not the Linkup SNMP trap.


  

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