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DHCP options on a Cisco C1812 router


Hello ppl.

I am going to get some wyse thin clients up and running on our departments. Each department communicate with the main-office through Cisco C1812 routers.

In order to get functionally DHCP up and running, I need to

     A - Configure some Dhcp options on the C1812 routers

     B - Perform a DHCP relay from each department to the main-office

Option B will cause some additional issues, so is not preferred.

The question is: Does the Cisco DHCP-client have an option for configuring DHCP options? I need to put in among others, an option 161, a string value pointing to a ftp-server. Can this be done? And if it can, I sure would be glad if somebody can give me the right syntax

I have recently started working here, therefore I am not certain of the IOS-version on the router, as I still not have the logon-information, but I will aqquire this shortly.

Regards Jon


Andrew Cink

ip dhcp pool

network x.x.x.x y.y.y.y

default-router x.x.x.x

dns-server x.x.x.x


ie, option 156 type string ftpservers=

See link..

Good luck!


Thanks for the reply Andy!!

It is not possible to configure something like

'option 156 type STRING'

String is not recognized as a valid syntax.

The options I can use is 'ascii', 'hex', 'instance' and 'ip'

Maybe it will work just using 'option 161 ip x.x.x.x', even if my Windows dhcp-server is configured with string? 161 is obviously the option I need to configure.

Regards Jon

My bad, in windows world it's a "string" value. In Cisco world it's an ascii value. The main two you will use for most purposes are ascii or IP. If you're serving something that is just an IP address, like a DNS server, a NTP server, etc, you use IP. If you have to pass in a sequence of characters, like "bootserver=,vlanid=101" then you put it in as an ASCII value.

If windows is configured with a string value, I'd use ascii. If it doesn't work, try switching it to IP


Yea.. thta's what I figured.

Thanks for all the help Andy!

I configured to use 'option 161 ip x.x.x.x'' before your answered my question. On my windows Dhcp server the option is actually only passing through an ip-address (or hostname), so pretty sure this will solve the issue for me.

Will (hopefully) have this tested within a week or two.

Thanks again.

Regards Jon

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