802.1x configuration checking

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Nov 4th, 2007
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Hi all

I need to deploy 802.1x with mac-authentication in the network.

Network Specificatios:

> The network diagram is attached.

> The connection between the branches are 10 Gbps and are operating through OSPF routing protocol.

> The ACS (4.1)appliance is residing in the HO branch only.( I have 2 ACS in replication mode, only one active all the time and the other is standby).

> My access switches are Catalyst 3560 with 12.0 IOS version.

> PCs are Vista operating system.

I need to know is there any problem if I deployed the 802.1x with mac-authentication for the whole network i.e the 5000 users must be authenticated through the ACS that resides in the HO.

Is the ACS processor will able to manage all the users authentication, if not what is the soluation?

Is there any latency will happen because of the authentication procees for these huge no. of users?

What is the IOS versions needed to support the 802.1x with my switches.

Finally, in many cisco documents I can see that before the user authenticated he can send only EAPOL, CDP and STP traffic, but in others you will see only EAPOL.. What is the right one?

I am waiting for any help.

Thanks and Best Regards


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Overall Rating: 4 (1 ratings)
bwilmoth Fri, 11/09/2007 - 06:57
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Complete these steps in order to configure 802.1x authentication on the switch:

Configure following commands on switch in Global configuration mode:

aaa new-model

aaa authentication dot1x default group radius

dot1x system-auth-control

radius-server host IP_address_of_ACS

radius-server key shared_key

Go into the interfaces connected to the clients using "interface interface_id" command and configure the following:

switchport access vlan

dot1x port-control auto

dot1x mac-auth-bypass

dot1x timeout quiet-period 15

dot1x timeout tx-period 3

dot1x reauthentication

In the case of Microsoft Windows XP client, for MAC authentication to work, disable the client in order to send an EAP request, so that switch can consider it as agentless host, and initiates the MAC authentication bypass process. This is the registry fix on Windows XP test machine:



Create an AAA client entry for the switch in ACS from the Network Configuration section. Use RADIUS as the authentication protocol.

On ACS, create an account for the client, based on its MAC address. For example, if the MAC address of the client is 00-15-C5-3A-E4-0D "

Username : 0015c53ae40d

Password : 0015c53ae40d

amady3381 Sat, 11/10/2007 - 03:46
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Hi bwilmoth

Thank you very much for your help..!

Actually I know the configuration and I tested every thing in the LAB with XP and Vista and it works fine.

Also there is a good feature called (Authentication with Inaccessible Authentication Bypass). I tested this feature and it works fine but I am asking about the design and the ACS appliance processor.

I have doubt with the authentication process latency because my network is very big with huge no. of users (5000 users).

Thanks for your help and reply


miklos.andrasi Thu, 11/22/2007 - 03:11
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I found the following:

Maximum users supported by the ACS internal database-There is no theoretical limit to the number of users the ACS internal database can support. We have successfully tested ACS with databases in excess of 100,000 users. The practical limit for a single ACS authenticating against all its databases, internal and external, is 300,000 to 500,000 users. This number increases significantly if the authentication load is spread across a number of replicated ACS instances.




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