Option 43 for Cisco LWAP

Brendan Forsyth bff at pvhs.org
Mon Oct 20 19:22:41 UTC 2008


That did it.  Thank  you Robert!
 
Brendan

>>> "Colantuoni, Robert" <rgc at buffalo.edu> 10/20/2008 1:06 PM >>>
 
This is what I have in my config:
 
        option controllers code 43  = string;
 
        # http://www.cisco.com/univercd/cc/td/doc/product/wireless/airo1130/1130hig5/113h_g.htm#wp1007971 
        #
        # The hex string is assembled by concatenating the TLV values shown below:
        # Type + Length + Value
        #
        # Type is always f1(hex). Length is the number of controller management IP addresses
        #  times 4 in hex. Value is the IP address of the controller listed sequentially in hex.
        #
        # For example, suppose that there are two controllers with management interface IP addresses,
        #  10.126.126.2 and 10.127.127.2. The type is f1(hex). The length is 2 * 4 = 8 = 08 (hex).
        #  The IP addresses translate to 0a7e7e02 and 0a7f7f02. Assembling the string then yields
        #  f1080a7e7e020a7f7f02. The resulting Cisco IOS command added to the DHCP scope is listed below:
        #
        # option 43 hex f1080a7e7e020a7f7f02

 
         # 10.3.240.2 == 0A.03.F0.02
         # 10.3.240.4 == 0A.03.F0.04
         option controllers f1:08:0a:03:f0:02:0a:03:f0:04;
 
 
 

----------------------------------

Robert G Colantuoni
CIT - Operational Support Services
University at Buffalo
rgc at buffalo.edu 
716.645.3552

 



From: dhcp-users-bounce at isc.org [mailto:dhcp-users-bounce at isc.org] On Behalf Of Brendan Forsyth
Sent: Monday, October 20, 2008 2:57 PM
To: dhcp-users at isc.org 
Subject: Option 43 for Cisco LWAP

Here is my problem.  When I use the Cisco DHCP server and add option 43 for telling the access points about where the WiSM controller is, everything works fine.  However from DHCP ISC v3.0.5, it doesn't.  Here are the two configs:
 
Cisco:
ip dhcp pool auto-pool
   network 172.17.112.0 255.255.255.0
   domain-name pvh.org
   option 43 hex f104.ac11.fe29
   option 60 ascii "Cisco AP c1200"
   default-router 172.17.112.1 
A wire shark dump of the ACK shows this:
Option: (t=43, l=6) Vendor-Specific Information
   Option:  (43) Vendor-Specific Information
   Length:  6
   Value: F104AC11FE29
 
The packet dump shows 2b 06 f1 04 ac 11 fe 29
 
ISC DHCP
 
option space Cisco_LWAPP_AP;
option Cisco_LWAPP_AP.server-address code 43 = string;
        class "Cisco AP c1200" {
                match if option vendor-class-identifier = "Cisco AP c1200";
                option dhcp-parameter-request-list 43;
                option vendor-class-identifier "Cisco AP c1200";
                vendor-option-space Cisco_LWAPP_AP;
                option Cisco_LWAPP_AP.server-address f1:04:ac:11:fe:29;
        }
Option: (t=43, l=8) Vendor-Specific Information
   Option:  (43) Vendor-Specific Information
   Length:  8
   Value: F104AC11FE29
 
The packet dump shows 2b 08 2b 06 f1 04 ac 11 fe 29
 
Note the two extra octets in the DHCP dump.  Also the class definition was obtained from Cisco's site about configuring ISC DHCP for option 43 functionality.
 
Any advice is appreciated.
 
Thanks,
 
 
 
Brendan Forsyth
Senior System Administrator
Poudre Valley Health Care
3702 Automation Way
Fort Collins CO 80525
bff at pvhs.org 
(970) 495-7731 office



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