Windows DHCP across subnets - Teaman 1.28.0025

Discussion in 'Tomato Firmware' started by EDDYMERCKX, Oct 1, 2012.


    EDDYMERCKX Network Guru Member

    Tomato Firmware v1.28.0025 Teaman-VLAN-SNMP-PPTPD ND VPN on WRT54GL 1.1


    I've successfully VLAN'd my network using a WRT and an HP ProCurve 1810g-8 with a Time Capsule as an AP for home wireless clients. The WRT provides access to guest wireless. Config is as such:

    VLAN1 (br0) LAN DHCP disabled
    VLAN10 (br1) LAN1 DHCP via W2K8R2 box (wired clients)
    VLAN11 (br2) LAN2 DHCP via WRT (home wireless via TC)
    VLAN12 (br3) LAN3 DHCP disabled (guest wireless interface assigned here)

    Port 4 is tagged for all VLANs on WRT with port 1 on the 1810 tagged as well. Subsequent ports on 1810 are untagged for access to various subnets with port 2 mirroring port 1.

    Everything works as it should with DHCP enabled on the WRT. I have LAN access set up how I want it and all is grand. I should be satisfied with that but would like to use Windows to provide DHCP addressing, which works, of course, in the network segment that the DHCP server resides. No addressing occurs on either of the wireless VLANs. The server is housed in a SFF case so additional NICs are out of the question and as far as I understand it, DHCP relay would require a node in each segment pointing to the DHCP server in VLAN10 (LAN1) with my current configuration.

    What are my options to get this working aside from purchasing a layer 3 switch? Is there something I'm missing in dnsmasq that would relay DHCP requests across subnets?

    Any input is appreciated...

    EDDYMERCKX Network Guru Member

    Anyone? Bueller?
  3. gfunkdave

    gfunkdave LI Guru Member

    I was always under the impression that DHCP worked via LAN broadcast and therefore can't be sent across subnets.
  4. PeterT

    PeterT Network Guru Member

    I seem to recall on cisco routers an option ip helper-address that was used to specify the IP address of the DHCP server. This allowed the broadcast to be intercepted by the router, and then forwarded to the DHCP server.

    EDDYMERCKX Network Guru Member

    That is correct. The ProCurve series allows it as well but my managed switch is only layer 2 and thus, has no routing capability. There is a dhcp helper addition for dnsmasq but I am unfamiliar as to how to incorporate that with my current version of Tomato and don't really have the time to pursue this avenue, if it is even possible.

    I guess this is an informal feature request for a dhcp relay agent in Teaman's Tomato but if not I guess I should start considering buying a cheap, layer 3 switch. I've been eye-balling but $500 for a gig ethernet switch is mighty steep for a home network. Especially considering I am in greater need of a NAS than more infrastructure.
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