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Roaming between two wireless access points

Discussion in 'Tomato Firmware' started by bhall7, May 18, 2012.

  1. bhall7

    bhall7 Addicted to LI Member

    Hello,

    I have an RT-N16 and a Linksys E3000 both running Tomato USB v. 1.28.9054 with wireless configured with the same SSID and same security key (WPA2, AES). The RT-N16 is the main Internet gateway, and the Linksys E3000 (no DHCP, manually assigned IP address in the same subnet) is connected to the RT-N16 via CAT-5e. Both devices are set to "Auto" on the wireless channel.

    What's weird is that when I switch from one AP to the other (walking from one end of the house to the other), I lose Internet connectivity and I need to disable my wireless adapter on my laptop and then re-enable it, in order for connectivity to be restored. Any ideas why this might be happening?

    Any tips for optimal wireless client roaming between wireless access points?

    Thanks!
     
  2. RonV

    RonV Network Guru Member

    You need to set up the channels manually in this type of configuration. I have an access point on each floor of my house:

    Basement: channel 1
    1st Floor: channel 6
    1sd Floor: channel 11
     
    TX CS Aggie likes this.
  3. TX CS Aggie

    TX CS Aggie Serious Server Member

    on you e3000 along with no DHCP, manually assigned IP address in the same subnet
    Set:

    Default Gateway : RT-N16 network IP (Example "192.168.1.1")
    and
    Static DNS1 : RT-N16 network IP
    Static DNS2 : RT-N16 network IP
    Static DNS3 : RT-N16 network IP

    then

    Set your RT-N16 and e3000 to different wireless channels that are at least 5 apart. (Example 1 and 6)

    also, make sure the manually assigned IP address on your e3000 is outside of the RT-N16 DHCP Server IP Address Range. Meaning the e3000 would be for example 192.168.1.2 and the DHCP Server Range would be 192.168.1.50~192.168.1.100.


    please post your results.
     
  4. bhall7

    bhall7 Addicted to LI Member

    Ah, interesting. I'll have to do a site survey to determine which channels have the least interference, and then manually assign different channels. Both devices are currently set to automatic for channel negotiation, based on a recommendation someone made. I would think that the auto channel assignment would be able to figure it out, but maybe not.

    Further complicating the issue, is that the RT-N16 just has 2.4Ghz, but the Linksys E3000 is dual band and uses both 2.4Ghz and 5Ghz bands. Should I also assign a different channel manually on the 5Ghz device, or should it not matter?

    When I roam from the RT-N16 (2.4Ghz) to the E3000 (5Ghz), I am able to verify that the wireless client actually does change channels (in this case, frequency bands by switching from 2.4Ghz to 5Ghz), but I still need to disable/re-enable my wireless device in order for it to work properly. Thoughts?
     
  5. bhall7

    bhall7 Addicted to LI Member

    Thanks TX CS Aggie for the reply. This is exactly what I'm doing, with the exception of manually assigning different wireless channels. The manually assigned IP address of the E3000 is outside of the range of DHCP addresses handed out by the RT-N16. Wireless clients that connect to the E3000 use the RT-N16 as the gateway and hit that device for DHCP.

    I'll experiment with manually setting channel spacing on 2.4Ghz, but not sure what to do about the 5Ghz band.
     
  6. TX CS Aggie

    TX CS Aggie Serious Server Member

    back when i was using DD-WRT on my WRT600n assign a channel manually to the 5Ghz increased my signal strength but I have had no such issue with my current e3000 running tomato, so your call. I don't think it is possible to roam between 2.4 and 5 automatically.
     
  7. bhall7

    bhall7 Addicted to LI Member

    Maybe this is what is causing my trouble: roaming between 2.4Ghz and 5Ghz. I may try turning off the 5Ghz radio to see if that helps. The only disadvantage, of course, being that I wouldn't benefit from higher speeds on 5Ghz.

    Also, I've been wanting to update to a more recent version of Tomato USB (still using a 2010 build from tomatousb.org, which seems stable enough). But, I'm so confused by all the different versions and mods and forum posts. What's the best build out there today? And, how can we trust that whatever version hasn't been injected with some type of malware? We really need a central source for the latest Tomato efforts. Any help would be greatly appreciated. Sorry to change the topic of the thread!
     
  8. TX CS Aggie

    TX CS Aggie Serious Server Member

    Depending what you are using the 5ghz for, your internet connection speed, and the wireless congestion in your area you might not even notice if you turn off the 5ghz.

    Personally I use Victek Mod have for years on other hardware with no issues. http://victek.is-a-geek.com/tomatoen.html
    I know that toastman's mod is very popular, but I have never used it.
     
  9. Toastman

    Toastman Super Moderator Staff Member Member

    You don't actually need to assign separate channels, which would make for faster handover, but mostly we use AP's on different channels so as to get higher speeds and less interference on each.

    The use of channels other than 1, 6, and 11 has also created problems.

    In general, Auto channel negotiation is a bad idea. What works one moment will not work the next as the router leaps all over the place, landing on top of other routers and causing them interference before jumping again. You've lost control of the situation and the goalposts are constantly moving. And no, this stupid "feature" does not really know what channels are "clear", it doesn't work properly.

    None of the current builds have any type of malware. There is no central source, the mods are separate and different, but they are based on the same code and just incorporate what each modder feels is most appropriate. You should not fear any of them.

    The build you are using is quite old, many hundreds of updates have been made since then, and many improvements.
     
  10. bhall7

    bhall7 Addicted to LI Member

    Thanks Toastman for the good info. What build do you recommend for both the RT-N16 (need USB support, file & printer sharing, SSH, and VPN) and the E3000 (only basic features needed, since this is only acting as an AP/wireless switch)?

    Thanks!
     
  11. apnar

    apnar Network Guru Member

    I agree roaming from 2.4 to 5 may be causing your issue. I'd set the RT-N16 and E3000 to the same SID on 2.4 with static channels as suggested above but give the E3000 a different SID on the 5GHz band (so you could still use it if you want although won't roam to it automatically). Also can you provide some more info about what is happening when it's broken? Do you still have an IP address? Can you ping one or both of the routers IPs?
     
  12. Mercjoe

    Mercjoe Network Guru Member

    Late to the party here but I have to ask, why don't you just have the SSID's, passwords and CHANNELS all be the same?

    I also have routers at the opposite end of the house. I have one set as the master and the other just a WDS endpoint. I can walk from one end of my properly (initially linked to the 3500l) and walk to the other side and end up on the WRT54G with NO loss in connectivity. It just hands off from one radio to the other.

    I have done this with my laptop while in a video spyke call and never lost the connection or lagged out.

    I have the radio channel assigned on both routers I use static IP's for all wired connections and DHCP for the wireless items and for guests.
     
  13. Toastman

    Toastman Super Moderator Staff Member Member

    I have 28 access points interleaved channels 1,6,11 and with same SSID, handover is also seamless. But that's with WRT54GL's - no 5GHz. TBH I don't see why having 5GHz should slow anything down but it's possible that handover between bands might be iffy.

    With different SSID the client would have to re-register. It might not buffer enough video etc. to tide it over the gap...

    Be aware, many things concocted by Apple don't work well with other systems.
     
  14. bhall7

    bhall7 Addicted to LI Member

    OK, here are the results of my testing:

    I moved the 5GHz wireless to a different SSID just to take the 5GHz out of the equation. For purposes of troubleshooting, I'm not even bothering to connect to the 5GHz (although I don't think it makes a difference). The two 2.4GHz access points (RT-N16 and E3000) are both on the same SSID, one on channel 1 and one on channel 11 (manually assigned). The laptop properly roams from one AP to the other (I can see the client change 802.11n channels, but the SSID is still the same). Here's where things get weird. The IP address stays the same after the handoff, and the WiFi signal stays strong, but the connection simply does not work, and after a few minutes, the Internet connection reports "No Internet Access." I tried renewing DHCP, but it assigns the same IP address, and the connection still doesn't work. When I disable the connection and re-enable it, things work fine again (same IP address given).

    Any ideas?
     
  15. Toastman

    Toastman Super Moderator Staff Member Member

    Is there a route set from the AP to the gateway?
     
  16. apnar

    apnar Network Guru Member

    This sounds like an issue with the client. Have you tried different clients? Updating your client's drivers? If you leave a ping running (ping -t [IP]) toward each router do they continue after the handoff?
     
  17. bhall7

    bhall7 Addicted to LI Member

    OK...I just did a continuous ping from the client (MacBook) to the RT-N16 (gateway). I walked to the other end of the house, the client hopped on to the E3000 (noticed the channel change), and the pings stopped and the connection seemed to die (even though it showed the WiFi signal at full strength. If I simply disable and re-enable the NIC on the MacBook, it works fine.

    Booted my MacBook to the Windows 7 partition (Boot Camp) and ran the same continuous ping. A bunch of the ping requests timed out, and it kept its connection to the original AP with a super weak signal (it would not jump to the second, stronger AP--even after disabling and re-enabling the NIC or trying to manually re-connect to the wireless network--very strange).

    Tried a completely different Windows 7 laptop, ran a continuous ping to the gateway, and it jumped fine to the other AP flawlessly, and back, and only one or two ping requests dropped--very solid.

    My conclusion is that there is some combination of wireless settings on my Tomato devices and the NIC on my MacBook that is causing the connection to fail completely when switching APs (in OS X), or there is an issue with the NIC itself (Broadcom BCM43xx 1.0 [firmware version 5.10.131.42.4]). Updating hardware drivers on OS X isn't as straightforward as it is on Windows, and the detailed NIC settings certainly aren't as accessible on OS X. Perhaps I may be able to find a firmware update for the NIC itself and flash it in Windows (highly unlikely, but something I may look into).

    I'm thinking this might be a good opportunity to update my devices to K26USB-1.28.7498 Toastman (You win, dude, for your responsiveness and helpfulness).

    Thanks so much to everyone who continues to help. Any further suggestions would be greatly appreciated.
     
  18. Monk E. Boy

    Monk E. Boy Network Guru Member

    Stupid question here, but how is the E3000 connected to the RT-N16? Did you connect an ethernet cable to a LAN port on one router with the other end connected to a LAN port on the other router?
     
  19. bhall7

    bhall7 Addicted to LI Member

    @Monk, Yep. Connected via CAT-5e GB from one of the LAN ports on the E3000, to one of the LAN ports on the RT-N16, just as you describe.
     
  20. mvsgeek

    mvsgeek Addicted to LI Member

    I couldn't help but notice that Mercjoe and Toastman have WRT54GL's in their (working) setups, which takes 802.11n out of the mix. Is your 'solid' Win 7 laptop n-capable, or is it falling back to a 802.11g connection? You mentioned that you can see your Macbook change 802.11n channels before it stops working - have you tried setting the routers to 'g only'? Maybe the issue is n-related.
     
  21. bhall7

    bhall7 Addicted to LI Member

    @mvsgeek, The solid Win 7 laptop does have 802.11n support (Intel WiFi Link 5100 AGN). It's the Broadcom BCM43xx NIC that seems to be giving me problems in both OS X and Windows 7 (dual boot machine via Boot Camp). In either case, I moved wireless n support to a separate SSID completely, to rule out any potential issues relating to switching between the 802.11b and 802.11n.
     
  22. apnar

    apnar Network Guru Member

    Just to clarify, what you did was change the 5GHz radio to a separate SID. On the e3000 both the 2.4GHz and 5GHz radios support 802.11n. What mvsgeek is suggesting you try is to try setting both access points to G-Only for the 2.4GHz radio to test if the issue may be with 802.11n support on the Mac.
     
  23. bhall7

    bhall7 Addicted to LI Member

    The clients are connecting via 802.11n because I see the connection rate in the 130Mbps range, and I see 802.11n in the connection status of my wireless NIC. But, I could try what you're suggesting and explicitly set both APs to 802.11g, etc.

    Just a side note, I upgraded the E3000 to the latest Toastman build this evening, and things seem to be going well. I'm still doing further testing. I wish there were a way to tweak the roaming aggressiveness of my Broadcom NIC on OS X. Any Mac experts out there know if this is possible?

    Thanks!
     
  24. crashnburn

    crashnburn LI Guru Member

    Interesting discussions. I have similar situation coming up at home.
     
  25. gfunkdave

    gfunkdave LI Guru Member

    Part of the problem may also be the wireless drivers on the laptops. I've noticed that many Windows wireless drivers in particular really like to hang on to very weak signals rather than switching to a stronger one.
     
  26. gutsman7

    gutsman7 Networkin' Nut Member

    Try changing to bg mixed to rule out wireless driver on your devices, could be the issue.
     
  27. PigMan9080

    PigMan9080 Network Newbie Member

    Guys, sorry for activating a really old post. I don't know the Tomato drivers very well but the problem here sounds very common. Consumer routers cannot talk to each other unlike Cisco Aironet device which can handoff the connection for roaming to another AP. It will be nice if it can.
     

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