Network and Telecom Strategies Blog

My upcoming Catalyst conference presentation

Posted by: Paul DeBeasi

Many enterprises are considering Wi-Fi CERTIFIED™ 802.11n draft 2.0 deployment because it has significant advantages over existing wireless technologies. However, these advantages present the enterprise network manager with important deployment considerations. At the upcoming Burton Group Catalyst Conference in July, I will examine the various deployment considerations for 802.11n in the enterprise. Some of the topics I will discuss are listed below.

Most existing 802.11 devices operate in a single frequency band, (e.g., 2.4 GHz or 5 GHz). 802.11n is different because it is specifically designed to operate in both the 5 GHz and the 2.4 GHz frequency bands. So 802.11n presents an opportunity for enterprises to reconsider which frequency band(s) to use. I will discuss some of the tradeoffs and issues enterprise managers need to consider.

Legacy 802.11 access points (APs) have a maximum power draw that is very close to the IEEE 802.3af Power over Ethernet (PoE) maximum of 15.4 watts. However, many 802.11n APs will consume more power than legacy APs. Enterprise AP vendors have addressed this problem in several ways and enterprise IT managers must consider which approach they will select.

802.11b/g/a APs typically use Fast Ethernet ports to forward traffic onto the wired network. Because the 802.11n data rate is designed to exceed the 100 Mbps capacity of Fast Ethernet (especially when using 40 MHz channels), most new APs will use Gigabit Ethernet for wired Ethernet communication. Therefore, some enterprises may choose to upgrade a portion of their wiring closet switches, and possibly their cabling, to provide gigabit Ethernet links to their 802.11n APs.

WLAN controllers that perform the data-forwarding function must backhaul all wireless traffic from hundreds of 802.11n APs, and so each controller will likely need to support several Gigabit Ethernet connections. WLAN controllers that distribute the data-forwarding function to the AP will need only a single Gigabit Ethernet connection.

802.11n presents a new security challenge because existing hardware sensors, without software updates, may not be able to recognize 802.11n APs. Therefore, it is important for enterprise managers to update wireless intrusion detection systems (IDSs), regardless of whether or not they plan to deploy 802.11n.

802.11n will impact network management tools. For example, spectrum analyzers must be able to recognize MIMO spatial streams, and visually communicate network behavior to the user. Therefore, enterprise managers will need to upgrade their network management tools in order to manage 802.11n networks.

Please join me in beautiful San Diego, July 27 – 31, for a discussion of these issues and many other interesting topics. Learn more about the Burton Group Catalyst Conference here: http://www.catalyst.burtongroup.com/Na09/.

The new battlefront: RF Management

Posted by: Paul DeBeasi

Wireless LAN (WLAN) Radio Frequency (RF) management is poised to become the new competitive battlefront. This includes technologies such as beamforming, smart antennas, and any other techniques used to control the wireless LAN physical layer. One might think that 802.11 technology innovation is slowing down, and that future competitive battles will primarily rely on marketing fluff, but not so.

Cisco announces Aironet 1140 series and M-Drive

Posted by: Paul DeBeasi

Aironet 1140

The Aironet 1140 is Cisco’s next-generation 802.11n access point and is a significant advancement over its predecessor, the Aironet 1250.  The most significant difference is the fact that the Aironet 1140 has a maximum power draw that is within Power over Ethernet (PoE) limits. The Aironet 1140 is also thinner and lighter than the Aironet 1250, and uses internal antennas (see the table below).  In addition, the Aironet 1140 uses the same mechanical brackets as the Aironet 1250 in order to simplify AP replacement.

Where oh where is ultra-wide band?

Posted by: Paul DeBeasi

We have been hearing about ultra-wide band (UWB) for years, but where are all the UWB products? UWB is supposed to provide a standard, high-speed, wireless connection for your peripherals. Think “wireless USB”, or, “Bluetooth on steroids”. Imagine connecting cameras, printers, and storage devices using a wireless connection instead of a wired connection. Sounds pretty good! But where are all the UWB products?

Well, the problem is that there are at least 3 competing solutions. First, we have Cable-Free USB. Cable-Free is based on Icron’s proprietary ExtremeUSB technology running on top of Freescale’s UWB chipset. It is designed around the USB 2.0 specification so it uses the USB 2.0 drivers. In effect, it replaces a single USB connection with a wireless Hub and dongle approach. Unfortunately, it is proprietary and not widely adopted.

Next we have the Certified Wireless USB approach that is based upon the WiMedia Alliance physical layer and MAC layer definition. This approach is backed by heavyweights including HP, Intel, and Microsoft. Certified Wireless USB creates a new USB protocol and uses a Hub and spoke model, connecting up to 127 wireless USB devices. Unfortunately, chipsets are still in the $10 range, which is far too expensive for low margin consumer electronic devices.

Lastly, we have 802.11n. Yup, good ole Wi-Fi can get the job done. In fact, this summer Texas Instruments withdrew from the WiMedia alliance in order to focus on 802.11n instead. Why? Well, consider this. Many consumer devices already have embedded WiFi. Why incur the power, space, and cost burden to add a UWB chipset when 802.11n is already available and will achieve 180+ Mbps? There will be over 450 million 802.11 chipsets sold this year and over 100 million will be 802.11n!

My bet is that Certified Wireless USB will not see widespread adoption and that 802.11n will become the dominant method for wirelessly connecting peripherals. No way, you say? Well, if you disagree, voice your opinion by commenting on this blog post.

Burton Group 802.11n report - commentary

posted by Paul DeBeasi:

There have been many articles, emails, and blog entries written about the Burton Group report “802.11n: The End of Ethernet?”.  As author of the report, I’d like to clarify a few things.

1. Burton Group takes pride in the fact that we do not do ANY vendor-sponsored research.  We don’t even do vendor-sponsored white papers.  Burton Group clients are predominantly very large enterprises and rely upon our research for unbiased, vendor-neutral research.

2. The report specifically looks at LAN access networks.  Wired Ethernet will be used for many years for inter-switch trunks and data center connectivity.  But, for LAN access, wireless is the future.

3. Speaking of the future, the report is looking at the state of the wireless/wired market in the 2 – 3 year time frame, not in 2007.  In fact, enterprise 802.11n access points are not even shipping yet. I don’t expect RJ45 jacks to be ripped out of the walls.  Instead, we are going to see wireless slowly spread and eventually dominate LAN access.

4. Security is a broad topic so let's break it down.  802.11 networks provide authentication, data privacy, and data integrity.  If you use best practice wireless security (802.1X + WPA2 + AES encryption) you can deploy a wireless network with authentication/privacy/data-integrity that is just as good as a wired network. Sure, WEP was broken (and lots of companies still have WEP) but WEP is not a best practice. If you want strong wireless security, you have to use WPA2. It is true that wireless denial of service is a vulnerability but the real question is what level of risk can you live with and how much are you willing to pay for RF monitoring/mitigation?   Also, don't forget that a wired network is not perfectly secure.  Eavesdropping can occur on a WIRED network too (see http://www.governmentsecurity.org/articles/articles2/ACSI33-5-Emanations-and-Cable-Security.pdf_fl/). 

5. If you use IETF RFC 2544 as the basis for benchmarking, the latency of an 802.11n AP and a Gigabit Ethernet switch is not very different (both are well below the ITU guideline of 150 milliseconds for VoIP).  However, real world latency is impacted by traffic patterns and how the equipment is deployed. It is easy to create situations where wireless latency is high. For example, if you use 802.11b clients and configure the AP to allow connections even with very weak RSSI, then you are going to bring the network to its knees. However, many of the new 802.11n enterprise APs will have two radios.  A preferred configuration is to operate one of the radios in "mixed mode" @ 2.4 GHz (ie, compatible with 802.11g/b) and run the other radio @ 5 GHz for 802.11n laptops only.  In addition, the APs should be configured so that very weak RSSI signals are disconnected. Laptop clients tend to be "sticky" and hang onto their AP connection even when RSSI is weak. 

6. It is certainly true that 802.11b/g/a APs can exhibit instability. By "stability" I mean wireless connection reliability.  802.11n and best practice network design can alleviate a lot of the problems. Much of the instability with 802.11b/g/a networks is caused by multipath and co-channel interference. 802.11n makes use of MIMO (multi-input / multi-output) radio design that takes advantage of multipath to actually boost throughput and reliability. After decades of research MIMO technology will now be widely deployed in 802.11, 802.16 (WiMAX) and cellular networks. In addition, dense deployment of lightweight APs (& controllers) will improve stability through load balancing and dynamic radio management. Co-channel interference can be reduced (but not eliminated) by using 5 GHz spectrum and modern Wireless LAN systems (controller + APs). In addition, 802.11k (radio resource management) and 802.11v (station control) will be ratified by the IEEE in the next 12 - 24 months.  Taken together these two new standards will make a WLAN more like the cellular network (where the network controls roaming - rather than the station) and will greatly increase wireless stability.

802.11n - Ethernet Killer (eventually)

posted by: Paul DeBeasi

The IEEE 802.11n draft standard is the beginning of the end for wired Ethernet as the dominant local area network (LAN) access technology.   However, this does not mean that we are going to see a precipitous erosion of the wired Ethernet switching market.  The fact of the matter is that enterprise APs will not be generally available until the fall of 2007.  Vendors are still working on testing their products, fixing bugs, and tuning performance. 

When these products finally begin to ship, they will be used predominantly in pilot programs.  These early products will be more costly than 802.11g/a products and enterprises will want to “kick the tires” before committing to products based upon a draft standard.   In addition, these early products will not achieve the full potential of 802.11n.  So, at least in the near term, Mike Disabato is correct when he says that 802.11n is not ready for prime time. 

However, just wait until 2008 and beyond!  Prices will fall as volumes rise and early jitters over the draft status of 802.11n will fade away as the Wi-Fi Alliance continues their certification program.  In addition, refinements in system silicon, radio design, network control, wireless security, and power management will significantly improve 802.11n products to the point where it will begin to erode the switched Ethernet market. 

The skeptics are wrong.  Wireless WILL replace wires.  It’s just a matter of time…

802.11n(ot) Ready for Prime Time

Posted by: Michael Disabato

At the Catalyst North America conference, Greg Ennis from the Wi-Fi Alliance gave a credible speech on the benefits of 802.11n and why enterprises should consider moving to it in the near future. The major problem with 802.11n is that the standard is still not ratified after more missed dates than I can remember. This is very reminiscent of the debacle surrounding the ratification of 802.11g. In order to allay concerns about this, the Wi-Fi Alliance has instituted a certification plan for "pre-n standard" equipment. This is all well and good, and I applaud the WFA for attempting to jump start the enterprise market. However, when questioned about the possibility that the physical layer might change in a late revision of the standard, Mr. Ennis did not gave an answer that there was virtually no chance of that happening. That was not the "no chance" I had been hoping for. We are now faced with the possibility, however slim, that there might yet be a revision of the physical layer necessitating replacement of purchased hardware. In spite of the promises of backward compatibility with "pre-n" products, that does not make me comfortable. I don't know about you, but if I were running a network again, I'd limit my 802.11n deployments to specific, restricted test networks until the IEEE finalizes the standard.

Draft 802.11n Certification - A step in the right direction

posted by: Paul DeBeasi

The Wi-Fi Alliance (WFA) recently announced the draft 802.11n certification program. The program intends to verify draft N product interoperablity (based upon 802.11n draft 2.0). The program is a step in the right direction because it will bring some clarity to the current free-for-all that currently exists where (mainly consumer) vendors make bold claims of throughput, coverage, and interoperabilty without any 3rd party verification of those claims.

On the other hand, the draft N program is not a panacea. First, the program does not test all of the features in the standard. For example, the current certification program does not test 40 MHz wide channels at 2.4 GHz. Will the untested features be backward compatible when the final standard is ratified?

Secondly, there is some risk that the final standard will have some subtle interoperability or performance issues compared to the current draft 2.0. I've talked to CTOs at all the major silicon vendors and enterprise system vendors. Almost all say the same thing "the likelihood of interoperability issues with the final standard is small because ... yadda, yadda, yadda)". While I agree that the risk is low, you just will not know if there are any issues until the standard is ratified and the equipment passes certification testing.

Lastly, the final ratification date is a moving target. The IEEE announced another six month slip in the schedule the same week that the WFA announced their draft N certification program (bad timing!). The IEEE now anticipates that they will complete the standard NO EARLIER than March 2009. The longer it takes to finish the standard, the more the likely some subtle change will ultimately give an enterprise network manager heartburn.

So, the bottom line is that the WFA certification program will certainly help alleviate potential interoperability problems. However, enterprise network managers must evaluate whether or not the benefits gained from an investment in draft 802.11n equipment outweigh the risks.

More to come on 802.11n at Burton Group Catalyst Conference, June 28th, in San Fransisco. Eric Ennis of the Wi-Fi Alliance will discuss 802.11n and what it can do for the enterprise.