Could IPv6 Drown My Wireless Network?

IPv6WiFi

By now, the transition to adopt IPv6 networks is in full swing. Registrars are running out of prefixes and new users overseas are getting v6-only allocations for new circuits. Mobile providers are going v6-only and transition mechanisms are in place to ease the migration. You can hear about some of these topics in this recent roundtable recorded at Interop last week:

One of the converstaions that I had with Ed Horley (@EHorley) during Interop opened my eyes to another problem that we will soon be facing with IPv6 and legacy technology. Only this time, it’s not because of a numbering scheme. It’s because of old hardware.

Rate Limited

Technology always marches on. Things that seemed magical to us just five years ago are now antiquated and slow. That’s the problem with the original 802.11 specification. It supported wireless data rates at a paltry 1 Mbps and 2 Mbps. When 802.11b was released, it raised the rates to 5.5 Mbps and 11 Mbps. Those faster data rates, combined with a larger coverage area, helped 802.11b become commercially successful.

Now, we have 802.11n with data rates in the hundreds of Mbps. We also have 802.11ac right around the corner with rates approaching 1 Gbps. It’s a very fast wireless world. But thanks to the need to be backwards compatible with existing technology, even those fast new 802.11n access points still support the old 1 & 2 Mbps data rates of 802.11. This is great if you happen to have a wireless device from the turn of the millenium. It’s not so great if you are a wireless engineer supporting such an installation.

Wireless LAN professionals have been talking for the past couple of years about how important it is to disable the 1, 2, and 5.5 Mbps data rates in your wireless networks. Modern equipment will only utilize those data rates when far away from the access point and modern design methodology ensures you won’t be far from an access point. Removing support for those devices forces the hardware to connect at a higher data rate and preserve the overall air quality. Even one 802.11b device connecting to your wireless network can cause the whole network to be dragged down to slow data rates. How important is it to disable these settings? Meraki’s dashboard allows you to do it with one click:

MerakiDataRates

Flood Detected

How does this all apply to IPv6? Well, it turns out that that multicast has an interesting behavior on wireless networks. It seeks out the lowest data rate to send traffic. This ensures that all recievers get the packet. I asked Matthew Gast (@MatthewSGast) of Aerohive about this recently. He said that it’s up to the controller manufacturer to decide how multicast is handled. When I gave him an inquisitive look, he admitted that many vendors leave it up to the lowest common denominator, which is usually the 1 Mbps or 2 Mbps data rate.

This isn’t generally a problem. IPv4 multicast tends to be sporadic and short-lived at best. Most controllers have mechanisms in place for dealing with this, either by converting those multicasts to unicasts or by turning off mulitcast completely. A bit of extra traffic on the low data rates isn’t noticeable.

IPv6 has a much higher usage of multicast, however. Router Advertisements (RAs) and Multicast Listener Discovery (MLD) are crictical to the operation of IPv6. So critical, in fact, that turning off Global Multicast on a Cisco wireless controller doesn’t disable RAs and MLD from happening. You must have multicast running for IPv6.

What happens when all that multicast traffic from IPv6 hits a controller with the lower data rates enable? Gridlock. Without vendor intervention the MLD and RA packets will hop down to the lowest data rate and start flooding the network. Listeners will respond on the same low data rate and drag the network down to an almost-unusable speed. You can’t turn off the multicast to fix it either.

The solution is to prevent this all in the first place. You need to turn off the 802.11b low data rates on your controller. 1 Mbps, 2 Mbps, and 5.5 Mbps should all be disabled, both as a way to prevent older, slower clients from connecting to your wireless network and to keep newer clients running IPv6 from swamping it with multicast traffic.

There may still be some older clients out there that absolutely require 802.11b data rates, like medical equipment, but the best way to deal with these problematic devices is isolation. These devices likely won’t be running IPv6 any time in the future. Isolating them onto a separate SSID running the 802.11b data rates is the best way to ensure they don’t impact your other traffic. Make sure you read up on how to safely disable data rates and do it during a testing window to ensure you don’t break everything in the world. But you’ll find your network much more healthy when you do.


Tom’s Take

Legacy technology support is critical for continued operation. We can’t just drop something because we don’t want to deal with it any more. Anyone who has ever called a technical support line feels that pain. However, when the new technology doesn’t feasably support working with older tech, it’s time to pull the plug. Whether it be 802.11b data rates or something software related, like dropping PowerPC app support in OS X, we have to keep marching forward to make new devices run at peak performance.

IPv6 has already exposed limitations of older technologies like DHCP and NAT. Wireless thankfully has a much easier way to support transitions. If you’re still running 802.11b data rates, turn them off. You’ll find your IPv6 transition will be much less painful if you do. And you can spend more time working with tech and less time trying to tread water.

 

Cisco To Buy Meraki?

If you’re in the tech industry, it never seems like there’s any downtime. That was the case today all thanks to my friend Greg Ferro (@etherealmind). I was having breakfast when this suddenly scrolled up on my Twitter feed:

After I finished spitting out my coffee, I started searching for confirmation or indication to the contrary. Stephen Foskett (@SFoskett) provided it a few minutes later by finding the following link:

http://blogs.cisco.com/news/cisco-announces-intent-to-acquire-meraki/

EDIT: As noted in the comments below, Brandon Bennett (@brandonrbennett) found a copy of the page in Google’s Webcache. The company in the linked page says “Madras”, but the rest of the info is all about Meraki. I’m thinking Madras is just a placeholder.

For the moment, I’m going to assume that this is a legitimate link that is really going to point to something soon. I’m not going to assume Cisco has a habit of creating “Cisco announces intent to acquire X Company” pages out of habit, like this famous Dana Carvey SNL video. In that case, the biggest question now becomes…

Why Meraki?

I’ll admit, I was shaking my head for a bit on this one. Cisco doesn’t buy companies because of hardware technology. They’ve got R&D labs that can replicate pretty much anything under the sun given enough time. Cisco instead usually purchases for innovative software platforms. They originally bought Airespace for the controller architecture and managment software that originally became WCS. The silicon isn’t as important, since Cisco makes their own.

Meraki doesn’t really make anything innovative from a hardware front. Their APs use reference architecture. Their switch and firewall offerings are also pretty standard fare with basic 10/100/1000 connectivity and are likely based on Broadcom reference designs as well. What exactly draws in a large buyer like Cisco? What is unique among all those products?

Cisco’s Got Its Head In The Clouds

The single thing that is similar across the whole Meraki line is the software. I talked a bit about it in my Wireless Field Day 2 post on Meraki. Their single management platform allows them to manage switches, firewalls, and wireless in one single application. You can see all the critical information that your switches are pumping out and program them accordingly. The demo I saw at WFD2 was isolating a hungry user downloading too much data with a combination of user identification and pushing an ACL down to that user limiting their bandwidth for certain kinds of traffic without totally locking that person out of the network. That’s the kind of thing that Cisco is looking for.

With the announcement of onePK, Cisco really wants to show off what they can do when they start plugging APIs into their switches and routers. But simply opening an API doesn’t do anything. You’ve got to have some kind of software program to collect data from the API and then push instructions back down to it to accomplish a goal. And if you can decentralize that control to somewhere in the cloud, you’ve got a recipe for the marketing people to salivate over. For now, I thought that would be some kind of application borne out of the Cisco Prime family.

If the Meraki acquisition comes to fruition, Meraki’s platform will likely be rebranded as a member of the Cisco Prime family and used for this purpose. It will likely be positioned initially towards the SMB and medium enterprise customers. In fact, I’ve got three or four use cases for this management software on Cisco hardware today with my customers. This would do a great job of replacing some of the terrible management platforms I’ve seen in the past, like Cisco Configuration Assisstant (CCA) and the unmentioned product Cisco was pitching as a hands-off way to manage sub 50-node networks. By allowing the Meraki management software to capture data from Cisco devices, you can have a proven portal to manage your switches and APs. Add in the ability to manage other SMB devices, such as a UC 500 or a small 800-series router and you’ve got a smooth package you can sell to your customers for a yearly fee. Ah ha! Recurring, cloud based income! That’s just icing on the cake.

EDIT: 6:48 CST – Confirmed by a Cisco press release and as well by Techcrunch and CRN.


Tom’s Take

Ruckus just had their IPO. It was time for a shake up in the upstart wireless market. Meraki was the target that most people had in mind. I’d been asked by several traditional networking vendors recently who I thought was going to be the next wireless company to be acquired, and every time my money landed on Meraki. They have a good software platform that helps them manage inexpensive devices. All their engineering goes into the software. By moving away from pure wireless products, they’ve raised their profile with their competitors. I never seriously expected Meraki to dethrone Cisco or Brocade with their switch offerings. Instead, I saw the Meraki switches and firewalls as an add-on offering to compliment their wireless deployments. You could have a whole small office running Meraki wireless, wired, and security deployments. Getting the ability to manage all those devices easily from one web-based application must have appealed to someone at Cisco M&A. I remember from my last visit to the Meraki offices that their name is an untranslatable word from Greek that means “to do something with intense passion.” It also can mean “to have a place at the table.” It does appear that Meraki found a place at a very big table indeed.