Monday, September 28, 2009

Duct work !

I remember the first time I was in a meeting about the deployment of a computer system and there were plumbers at the meeting ! Now there's more plumbing under the raised floors than anything else. Well, last week I got to work with the guys from the sheet metal shop while they fabricated duct work for our Cisco Nexus 7018 switches
. This turns the side-to-side airflow into front-to-back airflow. The sheet metal shop did a great job on very short notice !!

-- Post From My iPhone

Monday, September 21, 2009

Video Killed the Radio Star

Okay, now I'm sure you're thinking, what the heck does that great Buggles hit from 1980 have to do with networking ? Or you may be cursing me because you'll be hearing "oh, uh oh" in that annoying high pitched female voice ALL DAY !!

Regardless, after years of anticipation (7 to be exact), on Friday Sept. 11th, the IEEE finally ratified the 802.11n standard. Of course, quite a few enterprises, including many university campuses, have been deploying 802.11n since at least 2007 when the WiFi alliance started certifying equipment to draft 2 of the standard. But long before the standard was ratified and even before there were many enterprise deployments, there was no shortage of articles heralding the end of wired Ethernet. I can't count the number of times I've been asked if we would stop pulling wiring into new buildings and go 100% wireless. My emphatic response has always been "No, wireless will be hugely popular, but wires are not going away any time soon".

So when I received an email notification from The Burton Group last week about a report entitled "802.11n The End of Ethernet", I was pretty sure what I would find inside the report. Still, I knew there was a good chance I would have to field questions about the report, so I thought I better check it out. What I found is that the report basically supported what I've been saying, although that may not be apparent on the surface.

One key thing to keep in mind is that network usage and requirements at a research university are NOT the same as your typical business. For example, the report points out that 802.11n will probably not have sufficient bandwidth for "large" file transfers. But how do they define "large" ? The report defines "moderate" file sizes as 2-8 MB, so presumably anything larger than 8-10MB or so would be considered "large". This is probably accurate for a corporate network where you typically have relatively small connections (1-10 Mbps) to the Internet. At IU we have a 10 Gbps (that's a 'G') to the Internet and it's quite common for people to very large (100MB+) files from the Internet. It's also common for people to load very large (100MB+) files such as Microsoft Office or Adobe Photoshop over the local network. The last time I downloaded Microsoft Office from IUWare (MacBook Pro on a Gigabit Ethernet data jack), I got well over 400 Mbps and it only took about 15-20 seconds to download ! Never mind the researchers who want to upload and download files that are 50-100 GBs and larger or IPTV with streams of 6-8 Mbps per user !

Typical, real-world performance for 802.11n is around 120-150 Mbps. But, keep in mind, this is half-duplex, shared bandwidth for each Access Point (AP), so performance for individual users can vary greatly depending on how many users are in the same area and what they are doing. At a recent Internet2 workshop in Indianapolis where we supplied 802.11n wireless, I often saw 50+ Mbps on downloads over 802.11n, but sometimes performance dropped down to around 10-15 Mbps. And if you're further away from the AP with lower signal strength, you could see even lower throughput.

Another important factor is that 802.11 uses unlicensed spectrum and therefore is subject to interference. Microwaves, baby monitors, cordless phones - there are many sources of potential interference. In a corporate environment, it might be easier to prevent sources of interference, but at a university, especially in student residences, it is quite difficult. I've been told that most students in our dorms connect their game systems to the wired network, even though they have wireless capabilities, because they have experienced drops in wireless connectivity that interrupted online games at inopportune moments. A 30 second wireless drop-out while your neighbor heats up some leftover pizza at 3am may not seem like a big deal, unless you've been playing on online game for the last 8 hours and are just about to win when the connection drops !

The third important factor, IMO, is the use of IP for what I'll generically call "appliances". Cash registers, card readers, security cameras, building automation systems, parking gates, exercise equipment...the list goes on and on and they all used wired connections. If the use of wired Ethernet for PC's decreases, it's possible the increase in wired connections for these "appliances" will more than make up for it !

IMO networking is not a fixed sized pie that is divided between wired and wireless such that when one slice gets bigger the other slice gets smaller. The pie is getting much bigger all the time - it just so happens that going forward, growth in the wireless slice will probably dwarf the growth in the wired slice !

So, just as radio is still alive and well almost 30 years after the introduction of the video, I suspect wired Ethernet will be alive a well many years from now.