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DHCP Option 156 - Shortel Phone System

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We have a Shortel phone system where I work and I am being asked to configure Option 156 as a DHCP option in support of the phone system. As I do not see this option available, do you have any suggestions?  


I am also not clear on where I can configure - ftpservers=

Don't see this being available either.


Thanks for any comments


Re: DHCP Option 156 - Shortel Phone System

[ Edited ]
Posts: 81
10712     0

Hello Tom,


You don’t find that option because of the reason that you’re looking at the predefined option space(DHCP) in NIOS. That’ll have industry standard options allocated by the IANA and defined by IETF standards(1-125). Options 126-254 are available for private use(As in your case) & is not defined by IETF standards. So you can define 156 as a custom DHCP option in the same option space with the appropriate option type. To do this, you may :


Go to Data management -> DHCP -> Option spaces -> Select ‘DHCP’ -> Add 156 here by clicking the ‘+’ icon with appropriate type. Now you would see option 156 for value assignment under ‘IPv4 DHCP option’ at any level. See if the client can now get option 156 configured(After appropriate service restarts followed by the configuration).


You can also create option spaces to define new groups of options. When a DHCP client requests vendor specific options, it makes a request using the vendor identifier set in option 60 and a list of requested vendor specific options (option 43). The DHCP server then responds with the list of replies for the various options encapsulated into option 43. Note that custom options defined in the DHCP option space are included in the options section of the DHCP messages that DHCP servers and clients exchange. Custom options defined in a user-defined option space are always encapsulated in option 43 in DHCP messages. You can apply options globally at the Grid level, or more specifically at the member, network, network container, range, host and roaming host levels.


To configure custom option space :


Data Management tab -> select the DHCP tab -> Option Spaces tab -> Click the Add icon -> IPv4 Option Space -> In the Option Space wizard, add the Name/Comment/Options -> Save the configuration and click Restart if it appears at the top of the screen. After you create an option space and add options to it, you can apply the options.


Having a quick look at , I hope the client is expecting the FTP server’s IP address through option 156 ? To pick the right choice for configuration, you may need to look at the DHCPDISCOVER packet from a traffic capture collected from DHCP server or the client itself.


Let me know if you still have any questions or if something’s not clear.


Best regards.

Re: DHCP Option 156 - Shortel Phone System

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Posts: 2
10712     0

Hi Malman.


Thanks much for your input.

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