Seamless roaming between Wired and Wireless

[vaughancahill]

Hi All,

Quick question, looking for a solution/product/documentation that will allow the following if possible.

To Seamlessly roam from Wired to Wireless with out connectivity interruption.

We currently have a WLC/WCS system with 20 or so access points. Now managenent is hopeing to be able to "undock" their laptop and not have any connectivity interruptions while they transistion to wireless. E.g. not to lose any TCP sessions.

The only thing I have found that could provide this is AnyConnect VPN sessions over the top of wired/wireless.

This solution needs to scale for about 300 users so I don't think that's the best approach...

Any other ideas?

Thanks.

[Leo Laohoo]

If your wired and wireless IP address are on different subnets, I don't see how this could be done.

Another thing ... some clients have "client switching" disabled on the BIOS.  This is a feature that will allow simultaneous use of both wireless and wired network cards.  With this feature disabled, wired network is preferred and wireless card will enable itself when the wired network is disabled.  Let's presume that you have this option disabled, and the client is on a wired network, it will take the client time to decide to switch to wireless.  So again, I don't see this being possible.

[vaughancahill]

I agree, but management seems to think this can be done... This is same management that wanted a wireless only site for 300 users, but I have since convinced them other wise. I have already discussed that it won't be completely seemless but management says that have seen this at other companies. but Im having a hard time find out if it was completely seamless or if it was seemless from a user interaction point of view...

[Leo Laohoo]

but management says that have seen this at other companies.

Ask management WHERE did they "see" it and ask if that company can give a demo.

Someone has been "showing off" or bragging to someone from your company and now that someone has to back it up.

The good part of this exercise is that it puts you in a good light that you are someone who knows something and can back your claims.

[king.jason]

Offering "wireless only" isn't impossible but it does depend on your local RF environment and your budget. 300 people is really only a couple of floors (unless you're in central London) so as long as you get the AP density right you should be ok.

I worked at a bank that was "wireless only" in one of its offices. Some devices didn't do wireless so they had to put a couple of workgroup bridges in but there was no structured cabling on those floors (which saved them a ton of money.) They didn't seem to have too many problems with it.

Get your client roaming right and disable the lower speeds (depending on your site survey results, you could disable everything below 48Mbps) so that you don't have clients maintaining low-speed connections from the first AP they join. You would want to look at using dual-mode APs with dot11n (and band switching if you're not doing unified wlans.) I'd also consider the 3502s in 1:5 ratio as monitor APs for RF management.

Wired/Wireless seamless roaming is pretty much impossible: the mac addresses are different so they get different IP addresses. One possibility is whether you can team the local NICs and disable the wireless one when docked. Your AP would also have to be in HREAP mode and on the same subnet as the wired clients. The latest Intel PROSet utility supports 'adapter switching' which disables wireless when it detects an alternative network connection.

If anyone is aware of a way to get an XP or Win7 machine to team NICs, please let me know. I'm not a microsoft guy and would love to try this out.

Message was edited by: Jason King (to fix typos)

[rm760]

I have created networks in the past for devices such as laptops that connect to both the wired and wireless networks.  Both interfaces are enabled and the wired interface is prioritized via DHCP settings so that when the laptop is docked it is the primary and when the device is no longer docked the 802.3 interface is downl eaving only the 802.11 wireless connection up and available

[Leo Laohoo]

I worked at a bank that was "wireless only" in one of its offices. Some devices didn't do wireless so they had to put a couple of workgroup bridges in but there was no structured cabling on those floors (which saved them a ton of money.) They didn't seem to have too many problems with it.

Hi Jason,

I don't want to pick a fight with you but I'm just responding for other people to know.

This works if your usage of the wireless is emails and low traffic stuff.  Streaming high-definition videos can cause issues.  This may not be prevalent in the industry but it should be coming-to-stores-near-you-soon. 

[king.jason]

Hi Leolaohoo,

I agree that HD video introduces certain challenges but, with sufficient AP density, appropriate QoS policies and dot11n (with 40MHz channels), streaming HD video to a corporate WLAN should be fine. There are certain design considerations, sure, but the technology is there, it just needs to be configured properly.

Jason

(ps: as this is a discussion, I wouldn't have taken anything you said as picking a fight and I understand why you wanted to point it out: there are a lot of caveats with going "wireless only" so it's worth bringing these things up, even if only for completeness.)

[vaughancahill]

Hi,

The biggest concern I see with wireless only is that its an unlicensed spectrum and thus there are no guarantees around spectrum usage and interference. The biggest issue I see going solely wireless network over wired is potential risk from unidentified interference from neighbouring building RF, microwave ovens, even RF jammers. While you can seek help from your national spectrum regulatory body. I'd imagine this would take some time, may not even help resolve the issue as other devices are allowed to share the spectrum. During this spectrum interruption your entire wireless environment could be interrupted.

Now this has gone a bit off topic "wireless vs wired". I am looking at various solutions from Wired to Wireless to Wired. As to leolaohoo's comments about the bios disabling the wireless NIC when wired is connected. These are Dell laptops with Intel drivers and we don't have that function.

From what it sounds like layer3 seamless routing over difference physical mediums appears to be only possible with the Any Connect VPN layer on top.

[j-sutterfield]

Perhaps the demo was using NetMotion or Mobile IP? Both of those would provide seamless roaming from wired to wireless and even cellular.

Jason