SOLVED Multiple Routers and source of IP conflict

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

Normally IP conflicts in my experience are either one of two things. It either is genuinely conflicting or the device is defective. That said setting up a mesh/wds repeat network like what you are doing is dicey if you are intermixing manufacturers.

The only ones I have been able to get up and running without issue are commercial grade equipment designed for this purpose. DD-WRT while helpful isn't perfect and patches the underlying issue which is you are using equipment in a way it wasn't designed for.

It could be just as simple as you overloading the PSU of the unit or causing it to overheat. Dlink is notorious for doing that.

MAC filtering wouldnt help because its a routing issue not a switching one. My guess is that the conflict is arising from one of the client APs not being fully transparent within your network and you're seeing some kind of dual-nat conflict or similar where DHCP is being run on two devices confusing where its source is. Also if you are going to use them as a bridge all APs must be locked on the same wireless channel. (I'm assuming you already did this)

My suggestion would be one of two if you're looking for something foolproof that's going to be stable long term would be to unify chipsets or buy something that is better suited for what you are looking for. Specifically I would check out Ubiquiti.

Here's some source materials that I think should help you out:
http://maitechnowiki.wordpress.com/wds-repeating/

If you want the TLR version what you need is this

AP =Blue
Client Bridge 1 =Red
Client Bridge 2= Purp
Client Bridge 3 =Orange

Click to expand...

Example:
Blue needs to have NAT and DHCP enabled
force same spectrum (ie 20mhz or 40mhz only)
force channel to 6

Red = 192.168.1.25
Configure red to transparent bridge, disable NAT and DHCP
Enable AP but not DHCP allow all DHCP traffic to be run through Blue
Set as client repeater WDS or mesh
Set wireless channel to 6
force same spectrum (ie 20mhz or 40mhz only)
force same SSID as Blue

Purp = 192.168.1.50
Configure red to transparent bridge, disable NAT and DHCP
Enable AP but not DHCP allow all DHCP traffic to be run through Blue
Set as client repeater WDS or mesh
Set wireless channel to 6
force same spectrum (ie 20mhz or 40mhz only)
force same SSID as Blue

Orange = 192.168.1.75
Configure red to transparent bridge, disable NAT and DHCP
Enable AP but not DHCP allow all DHCP traffic to be run through Blue
Set as client repeater WDS or mesh
Set wireless channel to 6
force same spectrum (ie 20mhz or 40mhz only)
force same SSID as Blue

This way all traffic is transparent to the main AP, SSID does not change, IP address between APs do not change, channel does not change. More is detailed in the link I listed

Ahhhhh....

Thank you for your response and the thoughts.

I didn't want to have to get into the DD-WrT settings since that would be more apt for their Forum but no actually I didn't force a channel because the DD-Wrt Client Bridge setting automatically disables the DHCP for that client Router and does not allow you to force a channel or channel spectrum on THE CLIENT ROUTER

You can force one on the AP (Blue) but since the Client bridge setting will connect to the channel it's SSID is set and GateWay IP that you set it to, I didn't feel it would have mattered
It won't hurt me regardless so I'll force a channel and width.

Secondly, you're right the setup IS a dicey one, but it actually has been working well for me for most of the year and I only had difficulty originally because I was working through understanding the DD-WrT settings and features. I had originally went through (painstakingly I might add) all the troubleshooting and IP conflict nonsense on the initial setup so after re-reading my notes of that experience and recalling those issues I had thought I had all this licked.

Thirdly, although I DO know about NAT and have used it years ago for a gaming router, I didn't want to and haven't had to really mess with it with these routers and DD-WrT. I suppose for the purposes of troubleshooting I can try to assign it but at least to this point I haven't needed it as I've had MANY MANY devices all at the same time running sharing bandwith simultaneously and not had an issue (PS3 online [wired thru Purp] whilst, kids in separate bedroom on Netflix whilst another kid on iPad surfing web while wife is using WiFi on her Phone whilst I'm in the Man cave on one of the PCs [wired thru Red])

I HAVE had a 2 router DD-Wrt setup for almost 6 years where the routers were wirelessly bridged and naturally the equipment has been different but ever since the AC routers came out and I dabbled into the AC-66U I was enamored with the performance. I then added a third with success (although some hiccups at first) and now finally a 4th (with success). Again all were working flawlessly until the power outage...perhaps I've been lucky

Back the matter at hand; Another poster in another forum may have also shed some light as the Router when it loses power and reboots reassess the client pool and pings the clients. IF no response then it will reassign the ip address. I HAVE had this issue where one comp comes out of sleep (>20mins) and the conflict message appears. Looking into the Event Viewer and error logs it seems that the Purp router (ID'd by MAC address) is causing the conflict and interestingly enough it's a conflict on the 2.4GHz band not the 5.0GHz band that Red is connecting the 3 wired clients to not connect (although ALL of the clients seemed to be blocked by the conflict message)

I HAVE BOTH of Purps 2.4GHz and 5.0GHz MAC and IPs assigned in the DHCP of Blue so that is the source of my confusion but with the above I will have to add EVERY device into the DHCP to make sure that all are assigned an IP and assoc a MAC address and I will repost if the issue arises

I apologize for the lengthy response but I wanted to honor your informative post with an appropriate retort.
Please, by all means, continue with other thoughts

first off, use the 5 ghz band for bridging ONLY and i will explain why here in a minutes.

secondly turn off DHCP everywhere but your main DHCP Server (red?)

lastly, no need for NAT/Pat on the bridging routers as they are just repeaters nothing more.




the reason i say only use the 5ghz band is because of the spectrum, everytime you bridge out your connection it gets sliced in half. unless you're bridging from the main AP to your remotes thats ok in this situation. i'm sure your 2.4 band is getting a whole lot of chatter because of this, and it is potentially hurting your bandwidth.

now what also may be happening is Purple is using both connections as a bridge right? well, they have to auth and pass data somehow, i'm guessing your access points are getting bamboozled about connections and as i said above causing confusion, and duplicate packets being sent out of each band.

try turning off 2.4 ghz bridging where you can, it will save you headaches in the long run. oh, and report back

Zeta09 said:

I apologize for the lengthy response but I wanted to honor your informative post with an appropriate retort.
Please, by all means, continue with other thoughts

Click to expand...

No appologies required I'm glad I could help. Ideally what I would look at going foreward would be trying to either subnet each access point or make them fully transparent so you dont have to manually assign an ip address to each client device but instead to each client access point (router/switch)

Like I had mentioned earlier I did set up a network like what you described and it worked extremely well. If you do decide to start replacing things in the future I would highly reccomend "official" products capable of what you are looking to acomplish aka things like Ubiquiti or Cisco's Aironet routers so that you can extend the network outside or have better long term reliability.

I HAVE BOTH of Purps 2.4GHz and 5.0GHz MAC and IPs assigned in the DHCP of Blue

Click to expand...

This should not be required and would actually cause more problems then it would fix. In most dual-band routers the 5ghz and 2.4ghz are transparent so both access points are pulling from the same ip address pool so you would need one or the other not both. You could possibly set it up to show two seperate networks and two seperate DHCPs but that is completely unneccessary. You want to treat your satilite repeaters as both a router *AND* a client. The repeater connects to the main router just like any computer would; so pick either 2.4 or 5, whichever gives you better throughput. Then it rebroadcasts the signal, preferably transparently, to the devices behind it. Having your satalite connect with both 5ghz and 2.4 would cause an IP conflict as the AP has two seperate IP address sending the same traffic causing broadcast storms.

When you configure either mesh or WDS it is almost identical to what is used to provision cellular towers. In the case of cellular towers a VPN tunnel is set up to your source tower that contains your IP address so even if you leave the "network" or dhcp pool it can tunnel back to the original tower to pull things like your customer records and telephone number no matter where you are at. Same thing here with your access points. Blue is your source and you need a clean line of site to it from your other accesspoints so that way there is no loss of communication by things like NAT or a change in DHCP addressing. Having two seperate paths (2.4 and 5.0) without using something like spanning tree protocol would confuse the Blue router on where to send frames to first.

Based on what you said here's what I'd reccomend. Set the 5ghz spectrum as your backhaul, so use that to link the APs together and hide the SSID from your clients. Disable DHCP on the 5ghz and manually assign each access point an ip address as I suggested before. Something that makes sense like .25 / .50 / .75 &.1 etc. Then use the 2.4 as your connectable network for your clients matching the SSID, spectrum, channel and security to match between them

Take a look at this, this explains in greater detail what gangaskan and I are trying to explain:

http://www.tomsguide.com/us/how-to-wds-bridge,review-253-2.html

and also here:

http://www.smallnetbuilder.com/wire...ut-wireless-bridging-and-repeating-part-1-wds

Ok I'm back.


The SOLUTION?
Gangaskan and Sentential you were both right.
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 (Sent) 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 you both were saying. 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 (Sent). When I would turn the router completely off I could reset the rest and no issue occured. Despite it being a completely different router the same issue was occuring. 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 aobut 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 to you both for your responses.

I have been testing the AC setting to see if the real world speed is monumentally different but I am probably going to go with Gangaskan's rec about using 5.0GHz as the main band. I WOULD go AC on everything but the Wireless clients (iPhone, MacBook, Galaxy) are not on the AC standard (firmware fix?) so for now I'll keep the 2.4GHz then once I'm done seeing what I see with AC I'll go to 5.0Hz for the network and call it.

Thanks again guys!

Zeta09 said:

Ok I'm back.


The SOLUTION?
Gangaskan and Sentential you were both right.
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 (Sent) 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 you both were saying. 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 (Sent). When I would turn the router completely off I could reset the rest and no issue occured. Despite it being a completely different router the same issue was occuring. 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 aobut 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 to you both for your responses.

I have been testing the AC setting to see if the real world speed is monumentally different but I am probably going to go with Gangaskan's rec about using 5.0GHz as the main band. I WOULD go AC on everything but the Wireless clients (iPhone, MacBook, Galaxy) are not on the AC standard (firmware fix?) so for now I'll keep the 2.4GHz then once I'm done seeing what I see with AC I'll go to 5.0Hz for the network and call it.

Thanks again guys!

Click to expand...

Glad it worked!

As for which is the best band to use that is relative. The relationship between frequency and throughput is very VERY similar to the relationship between RPM and HP+Torque on a car. Higher frequency does often yield better throughput but if it is under stress at further distances it often does not. Very similar to a diesel vs gas or IPC You can tweek low frequency by using multiple band multiplexing together (like LTE) to achieve throughput at low frequencies. That is why we have and use multiple channel bands for wireless to mitigate interference and refractivity.

That is why most cellular bands occupy the 6-900mhz range not 2.4ghz for penetration and low error rate incidence at long distances. Higher frequency radio transmissions are far more prone to being disrupted than lower ones unless you increase transmitting power tremendously to brute-force it through.

TL;DR: Higher frequency does not equal speed, not always.

Use the best frequency and channel that provide the best throughput you can manage for the system. That may be N/G/B/A or AC it all depends. In addition link speeds to your accesspoint are different from your internet connection. Wireless is only about 50% as effective as a wired connection so as long as you are maintaining minimum link speeds you will see little/no benefit unless you actually use something that needs the throughput like a NAS or DLNA. Even then you are limited by the chipset's ability to either decode or transmit back.

For example my internet connection on uverse is 22mbps which means I need to maintain a link rate of at least 44mbps to "keep" my connection stable. 44mbps technicanlly can be achieved through wireless G but is better suited at distance by wireless N either 5 or 2.4 as link rates can go as high as 450mbps. In my case as long as I have atleast 50% signal I should maintain roughly 150-100mbps which is more than enough rendering the need for Wireless AC moot. However if I had a 50mbps or higher I would start to see link issues neccessating my move to Wireless AC.

Zeta09 said:

Ok I'm back.


The SOLUTION?
Gangaskan and Sentential you were both right.
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 (Sent) 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 you both were saying. 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 (Sent). When I would turn the router completely off I could reset the rest and no issue occured. Despite it being a completely different router the same issue was occuring. 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 aobut 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 to you both for your responses.

I have been testing the AC setting to see if the real world speed is monumentally different but I am probably going to go with Gangaskan's rec about using 5.0GHz as the main band. I WOULD go AC on everything but the Wireless clients (iPhone, MacBook, Galaxy) are not on the AC standard (firmware fix?) so for now I'll keep the 2.4GHz then once I'm done seeing what I see with AC I'll go to 5.0Hz for the network and call it.

Thanks again guys!

Click to expand...

no problem


in order to use the AC standard, i'm sure a new chip is in order, as the current wifi card may not be able to decyper 256 QAM, or if it does the manufacturer wont let you upgrade only because of a money monopoly


the only time you WILL see huge bandwidth increases in the 5ghz + ranges is only if you use channel width bonding (pairing 2 5ghz wide channels to make a 60mhz wide spread to communicate on) for example. its still 5ghz, but you're using 2 or more spectrum channels to increase your bandwidth.

this is similar to Ether-channel on network devices, pairing 2 or more (up to 8 in some cases) ethernet nics to create a pool of interfaces to blast on.

so technically, if i had 8 gigabit interfaces configured to port channel i could technically have 8 gigabits of bandwidth (or 800 for 100 megabit, 80gbs with 10g, etc ....)