DHCP and Route Priority

[David G.]

On Fri, Jun 2, 2017, at 12:44 PM, Bob Harold wrote:
> 
> On Fri, Jun 2, 2017 at 3:36 PM, Bill Shirley
> <bill at c3po.polymerindustries.biz> wrote:>> Classless static routes are used by an OS because they're more
>> specific:>> 
>> # -------------------------------------------------------------------
>> # -----------
>> option classless-static-routes          code 121 = array of unsigned
>> integer 8; # for Windows Vista and other non Windows DHCP clients
>> option classless-static-routes-ms       code 249 = array of unsigned
>> integer 8; # for Windows 2000 and XP clients
>> # -------------------------------------------------------------------
>> # -----------
>>
>> subnet 10.0.0.0 netmask 255.0.0.0 {     option routers
>> 10.96.0.12; . .    option>> classless
>> -static-routes
>>
>>         24,192,168,1,           10,96,0,9,      # lan1 192.168.1.0/24
>>         gw 10.96.0.9 23,192,168,64,          10,96,0,9,      # site
>>         #2 192.168.64.0/23 32,192,168,5,2,         10,96,0,76;     #
>>         serverB    192.168.5.2/32>> 
>>     option
>> classless
>> -static-routes
>> -ms        24,192,168,1,           10,96,0,9,      # lan1
>> 192.168.1.0/24>> gw 10.96.0.9
>>
>>         23,192,168,64,          10,96,0,9,      # site #2
>>         192.168.64.0/23 32,192,168,5,2,         10,96,0,76;     #
>>         serverB    192.168.5.2/32>> Not all dhcp clients are capable of utilizing them though.
>>
>>  Bill
>>>> On 6/2/2017 2:31 AM, Pavel Zhukov wrote:
>>> "David G." <lightman at fastmail.fm> writes:

>>>
>>>> Hi,  How can I communicate the priority of routes and routers via
>>>> DHCP? I'm trying to get computers on my network to use another
>>>> router for a specific subnet but everything is just going to the
>>>> default gateway. I'm using DHCP option 121 to set the route.
>>>>
>>> Hi, Which OS are you using? Classless routes should be set by
>>> dhclient script which is vendor specific.
>>>
>>>> Thanks!
>>>>
>>>>>> 
> 
> Try adding this to your DHCP configuration:
> 
> on commit {
>   log(info,
>     concat("REQUEST-LIST",
>       " IP=",binary-to-ascii(10,8,".",leased-address),
>       " MAC=",binary-to-ascii(16,8,":",hardware),
>       " req-list=",binary-to-ascii(10,8,",",option dhcp-parameter-request-
>       list)>     )
>   );
> }
> 
> Each time a lease is issued, it will log the list of DHCP options that
> the client requested.  If the client does not request code 121 or 249,
> then the server will not send them, because the client does not expect
> them and probably won't know what to do with them.> 
> -- 
> Bob Harold
>  
> _________________________________________________
> dhcp-users mailing list
> dhcp-users at lists.isc.org
> https://lists.isc.org/mailman/listinfo/dhcp-users

Thank you for the answers. I'll look into these options. I'm actually
using a mix of different clients, so the operating systems vary across
the machines. A major problem was the DHCP software was sending a
'classful' route with a netmask of 255.255.255.255. That was pretty
useless in my case.


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