[SOLVED] Multiple Router Setup conflicting IP issue

[Zeta09]

Hello All

I have had this problem periodically (2-3xs a year) but I'm looking for some fundamental answers first.
I have 4(four) AC-66Us but ONLY ONE is the AP. The rest are obviously wirelessly bridged. Yes they ARE using DD-WRT and I do understand many of the DD-WrT features. I come on bended knee now because of frustration and I could always be missing something. This is really NOT about DD-Wrt, although I could be missing a setting (I'll go to their forum about possible settings though) this is more about why I periodically get IP conflicts by seemingly only one of the routers but the entire network loses connectivity see below:

Setup goes like this:
AP =Blue
Client Bridge 1 =Red
Client Bridge 2= Purp
Client Bridge 3 =Orange

Red has 3 wired clients
Purp has 4 wired clients
Orange has 2 wired clients

Purp is the NEWEST of the four and all Wireless client bridges are running the same version of DD-WrT
The important part is this: I have the DHCP set on Blue. I have ALL THE WIRELESS CLIENTS with static IPs (it requires MAC addresses anyway) on Blue through the DHCP. Since the AC-66U is a dual band router I DO have Blue running both bands but ONLY Purp has Both Bands connected as a bridge

The MAIN connection is Red (Man Cave w/3 wired clients) and Blue (AP) this is where the heaviest traffic comes from. Purp was originally the AP but decided to make it a client AND IT IS THE CULPRIT with causing problems (it is functional and passed all the testing I did with it so I don't think it's a bad router). this was happening with the DIR-825 I USED to have before it was donated and replaced (it worked and is still working at my folks house).

The main issue is that whenever Purp is powered on and it attempts to connect it causes IP conflicts and essentially causes my entire wireless network to lose connectivity. I have looked and re-looked set and reset the settings and double checked x4s that it is set to Client Bridge with the appropriate Password and settings (AES on all) My settings are correct on ALL the Bridges. There are LONG stretches of time where everything HAS WORKED as it should. But I just recently had a power outage at my home which I had to reboot my settings on Blue. Thus the conflicts began again and I am now at my wits end as to why this is not working as it was. I had thought I had nipped this with the DIR-825 but I am missing something fundamental and thus I require assistance

So the question becomes why?

Do I need to have EVERY client (wired as well) have an IP/MAC set on Blue?
Why is it ONLY Purp that is seemingly causing the issue?
I DO have a PS3 AND Xbox but I had THOUGHT I had turned each wireless setting OFF
Could there be another wireless client that is attempting to connect that is throwing the DHCP off
IF I was to MAC filter perhaps then the issue would resolve?

Please advise and Thanks in advance

 

[bill001g]

First thing to look for is something that is giving out DHCP addresses that is not you main DHCP server.

You want to first do ipconfig /all and verify that the ip of the DHCP server is what you think it should be. There is a tiny chance that you have a duplicated ip for the DHCP server. You want to check the ARP table in the PC to make sure the mac address is the correct one.

The other thing that could be happening is when the router looses power it will start the DHCP pool from the beginning. What they normally do is ping the address before they give it out to another user. If a machine that owns the IP is say in sleep mode or has a firewall rule blocking ping it will not respond and the DHCP server gives the address out. When the original machine start to send traffic again you have a duplicate. What you can do to minimize this type of problem is to assign static DHCP entries in the dhcp router. This way it will always give a certain IP to a certain mac address and it will never be put in the available pool given to unknown mac addresses.

 

[Zeta09]

Ahhh...

You HAVE shed some light on this and looking back in the event viewer I DID find the MAC address of Purp which I knew it was the offending router but it seems to be only the 2.4GHz band that is conflicting?

Your comments also spur me to think that I will have to assign the MACs and IPs of EVERY device despite some of them being wired to ensure that NONE are mis-assigned by Blue. I will do so and repost the results when time allows.

Thanks for your suggestions and please (anyone else?) chime in with additional recs....

 

[Zeta09]

First thing to look for is something that is giving out DHCP addresses that is not you main DHCP server.

You want to first do ipconfig /all and verify that the ip of the DHCP server is what you think it should be. There is a tiny chance that you have a duplicated ip for the DHCP server. You want to check the ARP table in the PC to make sure the mac address is the correct one.

The other thing that could be happening is when the router looses power it will start the DHCP pool from the beginning. What they normally do is ping the address before they give it out to another user. If a machine that owns the IP is say in sleep mode or has a firewall rule blocking ping it will not respond and the DHCP server gives the address out. When the original machine start to send traffic again you have a duplicate. What you can do to minimize this type of problem is to assign static DHCP entries in the dhcp router. This way it will always give a certain IP to a certain mac address and it will never be put in the available pool given to unknown mac addresses.

Ok I'm back.
Thanks to everyone for the responses and help.

The SOLUTION?
Yes I had Purp set to use both bands and actually for a large part of the year this actually worked. Obviously it was unreliable if there was an event and resetting it was troublesome. All FOUR routers work fine since I interchanged each one to reset them and their settings. On my reset of Orange in the thinking I would replace Purp with it I started to use both 2.4 and 5 then I realized exactly what I was doing wrong. IF both are still N and just the bands are different then the AP has two sets of information to decipher and EVEN though each band had a MAC address and IP assigned in the sole DHCP it still was unreliable and cause havoc =broadcast storms. When I would turn the router completely off I could reset the rest and no issue occurred. Despite it being a completely different router the same issue was occurring. This had happened to an extent as well with the DIR 825 that I had written of in the earlier post that is working fine at the folks house.

So. Now I have ONLY one band in usage for each client bridge and it has been working without a hitch to date. Sentential, you were right about the ip address pool. The broadcast storms was the cause of the issues and amazingly still worked fairly well throughout this year despite the theoretical issue but per both your recs I'm going solo Band for now. It's working and stable. Thanks for your responses.