Regarding setting up DHCP servers on each WRT54G

Discussion in 'Tomato Firmware' started by Kiwi8, Nov 15, 2008.

  1. Kiwi8

    Kiwi8 LI Guru Member

    I have more than one WRT54G connected via WDS together.

    I would like to ask if setting up independent DHCP servers on each router is ok, and whether there are any benefits in terms of speed. Of course I know that setting up independent DHCP servers may be redundant and may be confusing, but I will utilise static DHCP to not issue the same IP to different computers.

    Thanks in advance.
  2. HennieM

    HennieM Network Guru Member

    Can do, and it will probably contribute towards failover redundancy, but speed... I don't think so.

    I'm not sure, but I think I saw an option where dnsmasq can be made to first ping an IP before it dishes that IP out. You might want to turn that on so 2 or more DHCP servers don't try to dish out the same IP.
    Alternatively have the different DHCP servers serve different IP ranges.
    Alternatively the static IPs you mentioned.
  3. Kiwi8

    Kiwi8 LI Guru Member

    Ok I have done it and tried it out.

    The result is that the DNS server, the gateway and the DHCP server (naturally) are pointing to the router that the PC is connected to.
    Example: a PC connected to Router B, which is WDS-connected to Main Router A.

    So the gateway address changes from 192.168.1.A to 192.168.1.B. Internet access is ok.

    So will it slow down the connection, or will it be the same?
  4. HennieM

    HennieM Network Guru Member

    I assumed you would override the gateway to the correct one in B's dnsmasq's config. Not overriding it may still work, and it would not really slow your traffic down as B would route/redirect to A (if B knows that A is the gateway), but you would lose a bit of redundancy if there were other paths to get to A.
  5. Kiwi8

    Kiwi8 LI Guru Member

    Ermm I did not input the gateway in B's DNSMASQ's config. I only put in the Basic -> Network part to key in A's address as the default gateway and DNS server.
  6. HennieM

    HennieM Network Guru Member

    Sorry, did not quite understand your post #3, but it seems you actually did override the gateway in A, so all PCs, irrespective of to which router they connect, get B as the gateway. That is the correct setup, and is the fastest and most redundant setup you could have i.t.o. traffic from where-ever on your network getting to router A.

    I.t.o. DHCP, you would most likely not notice any speed difference. The reason is (i) DHCP only takes place whenever a (new) PC starts up, and (ii) as your routers are in the same subnet, all DHCP frames are broadcast seamlessly to everywhere on your network, no matter which device it originates from.

    As mentioned above, you only gain a little bit of redundancy i.t.o. DHCP in case router A or router B - or more specifically, the _DHCP_server_ on router A or router B - goes down.

    You might as well not do the DHCP sever on router B, as, if router A goes down, you lose your internet connection anyway.
    However, I usually do something like that; i.e. configure a DHCP server on a 2nd device (your router B) to be identical to my main DHCP server (your router A), but then just disable the DHCP server on router B. It is there, it is configured, but I don't use it. Then, when my router A breaks or lose its DHCP setup or something, I just put router B in place of A, and turn on the DHCP server. Then I have time to sort out (the broken) A.
  7. Kiwi8

    Kiwi8 LI Guru Member

    Well, why I would want to keep DHCP servers on each router is because I have 3 routers, A, B and C. Supposing only A has the DHCP server, if A goes down, there is no DHCP server to issue out internal IP addresses to the other PCs in the other routers. I want to maintain the LAN connectivity between B and C. That's why the redundancy in DHCP servers. :)
  8. HennieM

    HennieM Network Guru Member

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