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In the November 18, 2003 column you describe how to configure an IOS-based switch to function as a DHCP server. Is this feature also available for switches running CatOS? If so, where can I find more information?

Thanks, -- John W. Saunders

Answer:

John,

Unfortunately, the CatOS doesn’t have any support for acting as a DHCP server. You can, however have the SC0 interface obtain an address dynamically using RARP, BOOTP or DHCP.

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The catch to doing this though is that the interface configuration must be cleared and the IP address of SC0 must then be 0.0.0.0 (no address). The switch will try repeatedly to broadcast for dynamic address assignments via those various protocols. If no responses are received within 10 minutes, the address will remain unassigned.

If an address is learned dynamically, it will remain through power cycle. Even if a renewal request fails to obtain a response, a learned address is still kept -- an interesting behavior. But, unfortunately, that is the only method of DHCP that CatOS is aware of currently.

I would like to say that at some point in time this will change, but the reality is that the recommendation is that you deploy Catalyst switching with the native IOS software. All new features and technologies seem to be destined to show up in the IOS versions of Catalyst software rather than the CatOS versions.

-- Scott

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Scott Morris, quadruple CCIE, JNCIE and all-around uber-geek, can often be seen traveling around the world consulting and delivering CCIE training. He recently accepted a new Senior CCIE Instructor position with Internetwork Expert! For more information on him check out http://www.uber-geek.net or for CCIE training check out http://www.internetworkexpert.com. You can contact Scott via editor@tcpmag.com. You can contact Scott about "Does CatOS Support DHCP? " at editor@tcpmag.com.