Forum

You are correct about the certification itself.

The hardware must be tested and approved by a WFA certified test lab - (which looks like a smaller list than it had been). See : http://www.wi-fi.org/authorized_labs.php

But exactly how, why or when a device gets listed there is up to the Mfg. Sometimes they get things certified, but don't list them. I know Cisco has done that.

Also, devices that were previously certified may not be listed because the mfg. is not a current WFA member.
That includes devices that were once part of their proprietary (secret) test bed.

WFA now adds the following text to, at least, one of their pages:

"Note:

Please be aware that some Wi-Fi CERTIFIED products may not be shown due to vendor listing preferences.

Products listed may not be available in all geographies or distribution channels. Please confirm availability with your manufacturer or distributor.

Only active member products are displayed "

Wlanman09,

That helps clarify things from a WFA perspective, thanks.

Another thing to watch with regards to full 300 or 450 speeds is if the card will do greenfield mode. I have discovered that there are some chipsets out there that don't allow it, so if you try to get 'full speed' you get hit by the 802.11n protection measures as soon as a a/b/g client appears on the scene.

Come on folks... even if you have two devices with both 3X3:3 systems you still won't net out anywhere near 300, let alone 450. Remember 802.11 has DIFS, PREAMBLE, Header, Payload, SIFS, PREAMBLE, ACK for each frame transfer. When in non-greenfield, you'll also have to add into that mix at least and additional PREAMBLE, CTS and the bare minimum. Possibly more if you've used both 20MHz and 40MHz channels.

You'll be lucky to net out somewhere in the high 100s. If you have to have protection on, it might be as low as the mid 30s.

Go through the entire protocol, not just the vendor's marketing literature. Better yet, actually test it in your own little lab. I don't mean look at the WZC's little task bar that says 'Connected at 300Mbs', but do actual throughput tests. THEN, and only after testing, go to your boss and set proper expectations.

By the way, AirMagnet's Wi-Fi Analyzer has some .11n tools to help predict net throughput, both up and down. (By the way those two will be way different in the real-world - Bye-Bye data flow symmetry)

Keith

Keith,

I agree - wish we were working with "n" gear, but that's probably a ways down the road.

Chris,

I see on the WFA database that only 418 out of the 1225 802.11n devices displayed there support Greenfield preambles. Not that the WFA is the ultimate source of information, but I think its a good indicator of the overall market place.

On the WFA Advanced Search page you can specify which of 7 "n" features you are interested in - all, none, or combinations thereof.

Keith has brought up a good point. Although 802.11n has a ton of "fancy enhancements" such as SM, Tx Beamforming etc, the basic access mechanisms and many of the frame exchange mechanisms are very similar to previous generations of equipment.

Remember getting 54 Mbps throughput from an 802.11g system ? It just doesn't happen.

For a particular block of data being transmitted [ on .11g ] the PMD clock will operate at say 54 Mbps, however "over time" the average throughput will be much less due to access mechanisms etc.

For example, take a single spatial stream on a 40 Mhz channel running 64-QAM with a GI of 800ns ( MCS Index value of 7 ). If we shrunk ourselves down and sat on the data line prior to the modulator with a tiny magic magnifying glass, we would truly be able to see 135.0 Mbp/s of data passing along. But it would be in "bursts", not continuous.

Similar ?ish? analogies can be found in the world of serial and packet switching WAN links.

If someone tells you that you have a data throughput of 1.544 Mbit/s on your T1 serial line, you don?t. You may have something close to it, but not 1.544 Mbit/s. You will have a line clocking rate of 1.544 Mbps. I often received calls from customers when I was running WAN links to explain the ?T-1 problem? [ or E-1 or SDH etc ]. A T-1 has a particular framing structure with ?overhead? bits for frame alignment, signalling etc. If you have truly 1.544 Mbit/s of data throughput, then you do not have a T-1.

Dave

I believe that Ciscos current range of products do not support N.

I will look at the WFA site as a source of reference now I know you can select the "n" features you are interested in.

I am of the understanding though that raw data rates at bes will be about 70% of the connection speed, purely as an absolute max with packet aggregation etc son for 300Mbps you could see around 200 rather than the 50% you would expect with b/g?

I just picked one model but there are others.

Beg to differ:

Cisco does support 802.11n

http://www.cisco.com/en/US/prod/collateral/routers/ps380/data_sheet_c78_459542.html

Product Overview

Cisco 880 Series Integrated Services Routers are fixed-configuration routers that provide collaborative business solutions for secure voice and data communication to small businesses and enterprise teleworkers. They offer concurrent broadband services over third-generation (3G), Metro Ethernet, and multiple DSL technologies to provide business continuity. Wireless 802.11n and 3G offer LAN and WAN mobility. The routers provide the performance required for concurrent services, including firewall, intrusion prevention, content filtering, and encryption for VPNs; optional 802.11g/n for mobility; and quality-of-service (QoS) features for optimizing voice and video applications. In addition, the web-based Cisco Configuration Professional configuration tool simplifies setup and deployment. Centralized management capabilities give network managers visibility and control of the network configurations at the remote site.
Cisco 880 Series Integrated Services Routers offer:
? High performance for broadband access in small offices and small branch-office and teleworker sites

? Collaborative services with secure analog, digital voice, and data communication

? Business continuity and WAN diversity with redundant WAN links: Fast Ethernet, G.SHDSL, ADSL2/2+, VDSL2, 3G, and ISDN

? Survivable Remote Site Telephony (SRST) voice continuity for enterprise small branch-office and teleworker sites

? Enhanced security, including:

? Firewall with advance application and control for email, Instant Messaging (IM), and HTTP traffic

? Site-to-site remote-access and dynamic VPN services: IP Security (IPsec) VPNs (Triple Data Encryption Standard [3DES] or Advanced Encryption Standard [AES]), Dynamic Multipoint VPN (DMVPN), Group Encrypted Transport VPN with onboard acceleration, and Secure Sockets Layer (SSL) VPN

? Intrusion prevention system (IPS): An inline, deep-packet inspection feature that effectively mitigates a wide range of network attacks

? Content filtering: A subscription-based integrated security solution that offers category-based reputation rating; keyword blocking; and protection against adware, malware, spyware, and URL blocking

? Four-port 10/100 Fast Ethernet managed switch with VLAN support; two ports support Power over Ethernet (PoE) for powering IP phones or external access points

? Secure 802.11g/n access-point option based on draft 802.11n standard with support for autonomous or Cisco Unified WLAN architectures

? CON/AUX port for console or external modem

? One USB 1.1 port for security eToken credentials, booting from USB, and loading configuration

? Easy setup, deployment, and remote-management capabilities through web-based tools and Cisco IOS? Software

Ah my apologies I meant N greenfield mode

Doh!!!

Stupid me they have an extensive N portolio as do most manufacturers

No problem. I was like... huh?