dhcp with two relay agents

[Simon Hobson]

fadey wrote:
>Thanks. It starts getting more clear. Basically now my question narrows
>down to following:
>
>I have this setup:
>
>shared-network router1 {
>   subnet router1.cable_modems {deny unknown-clients; ...}
>   subnet router1.emtas {deny unknown-clients; ...}
>   subnet router1.hosts1 {...}
>   subnet router1.hosts2 {...}
>}
>
>shared-network router2 {
>   subnet router2.cable_modems {deny unknown-clients; ...}
>   subnet router2.emtas {deny unknown-clients; ...}
>   subnet router2.hosts1 {...}
>}
>
>All router1 subnets share the same physical network. The same is true
>for router2 subnets.
>
>Now there is a DHCPDISCOVER relayed from router2 with GIADDR set to
>router2.cable_modems IP. It is an unknown-client (mac is not explicitly
>specified in dhcpd.conf). In this case will dhcpd be "smart enough" to
>DHCPOFFER an IP from route2.hosts1 subnet and NOT from router1.hosts*
>subnets?

Yes, this differentiation based on GIAddr is automagic.

However, and this is something that I hope some of the cable modem 
guys will chip with ...
I'm not sure you need the shared network at all. It could be that the 
cable equipment is capable of differentiating between the 
infrastructure kit, user end cable modems, and user kit - in which 
case I suspect the GIAddr received will be set to that of the 
appropriate interface.
Either that, or yu keep the shared network and can use something like 
vendor class to split the equipment into the appropriate subnets.
I've only vaguely followed the cable modem threads, so hopefully 
someone who's actually used this stuff can chirp up and fill in the 
blanks.

-- 
Simon Hobson

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