Public wifi – why use more radio spectrum than you need?

Here’s the second of my series of little rants about poor public wifi – this time, why use more spectrum than you need?

Using the Wifi Explorer tool, I was recently checking out a venue with a modern public wifi installation. Here’s what the 5GHz spectrum looked like:

crowded_5Ghz_spectrumI’ve redacted the SSIDs so that we aren’t naming names and we’re hopefully saving face.

You’re probably thinking “They aren’t using much spectrum at all“, right? All their access points are all clustered down on 4 channels – that in itself not being a good idea.

Note that they are using “wide” 40MHz channels – the signal from each access point is occupying two standard 20MHz channels. Networks are usually setup like this to increase the amount of available bandwidth, by using multiple signals on multiple radio channels at once between the base station and the client.

This was also a brand new installation, and the access points were supporting 802.11a, n and ac, and the Wifi Explorer tool reported each AP could support a theoretical speed of 540Mb/sec.

What if I told you the access circuit feeding this public wifi network, and therefore the most bandwidth available to any single client, was 100Mb/sec?

Vanilla 802.11a would give a maximum data rate of 54Mb/sec (probably about 30Mb/sec usable payload) on a single channel, this could be 150 or 300Mb/sec with 802.11n (MIMO). Plenty for getting to that 100Mb.

Thus rather than having as many as 4 overlapping access points sharing the same channels, this could be reduced significantly by only using 20MHz channels. This would result in less radio congestion (fewer clients on the same frequency), and probably wouldn’t negatively effect access speeds for the clients on the network.

There’s also the question of why all 6 access points visible in this sweep are spread across just two 40MHz channels.

The main reason is that DFS (Dynamic Frequency Selection) and TPC (Transmit Power Control) is required for any of the channels highlighted with blue numbers in the chart above – it’s also known as “Radar Detection”, because some radar operates in these channels. An access point running DFS will “listen” first for any radar signals before choosing an unoccupied channel and advertising the network SSID. If it hears any radar transmissions, it will shut down and move channel.

Sure, avoiding the DFS mandatory channels gives more predictability in your channel use, and means you aren’t affected by an access point needing to go off air.

However, an option in designing the network could be to use the DFS mandatory channels to increase available spectrum, but strategically place access points on non-DFS channels spatially in between those using DFS, getting away from the “listen on startup” phase (e.g. if there’s a need to reset an access point), or from the service suddenly going offline because of radar detection.

Also, remember that this is an indoor deployment and well inside a building. The chances of encountering radar interference are relatively low. I don’t recall seeing a problem using DFS when I’ve deployed temporary networks for meetings.

The other thing to note is that this deployment is not using a controller-based architecture. It is made of access points which can signal control messages between each other, but each access point maintains effectively it’s own view of the world. (Those of you in the Wifi space can now probably work out who I’m talking about.)

Is the above configuration using so few channels, and using them unwisely considering the target bandwidth actually available to the wifi clients, just asking for trouble once a few hundred users show up?

 

Waiting for (BT) Infinity – an update

I mentioned in my last post about my partner’s Mother moving home this week, and how it looks like BT have missed an opportunity to give a seamless transition of her VDSL service.

The new house was only around the corner from the old one, so should be on the same exchange, and maybe even on the same DSLAM and cabinet. It had previously had VDSL service, judging from the master socket faceplate.

20140624_103830

Was the jumpering in the cab over to the DSLAM still set up? Well, we dug out the old BT VDSL modem and HomeHub 3, and set those up.

Guess what…

20140626_144809The VDSL modem successfully trained up. The line is still connected to the VDSL DSLAM.

However, it’s failing authentication – a steady red “b“. Therefore it looks like the old gear won’t work on the new line.

But then the new HomeHub 5 they’ve needlessly shipped out won’t work either: we set that up too, and get an orange “b” symbol.

Evidently, something isn’t provisioned somewhere on the backend. Maybe the account credentials have been changed, or the port on the DSLAM isn’t provisioned correctly yet.

Does this look like a missed opportunity to provide a seamless transition, without the need for an engineer visit, or what?

 

Ken Morrison – A simple business philosophy

Recently the UK supermarket chain Morrisons has been in the news, regarding the state of the business, potential job cuts, and a lambasting for the Board at the recent company AGM from former chairman and straight-talking Yorkshireman Sir Ken Morrison, son of the company’s founder.

While CEO of the company, he was known for reportedly “skip diving” on visits to his Morrison’s stores – sifting through the bins to see what was being thrown out and wasted. Sir Ken has a simple philosophy to the supermarket business – “shop in your own shops, get to know your customers and don’t make presidential visits“.

It seemed to work well for him, for Morrisons was profitable for good number of years, until, in 2004, Morrisons acquired Safeway UK (by then already independent from it’s US namesake), a company who I used to work for as a teenager.

One of the things which used to irk me about the way that Safeway was managed was the way that the senior management conducted visits of the stores. When it was known that the regional manager was visiting, significant amounts of overtime became available. The store would be scrubbed top to bottom, the normally messy behind the scenes stockrooms would be tidied up, the shelves would be neatly filled and faced up, and almost every checkout would be open.

This resulted in the management not seeing the real experience, but some sort of show, or “shop in a bottle”.

The very “presidential visits” that Ken Morrison speaks of.

To borrow Sir Ken’s turn of phrase, they left with a “bullshit” experience of what shopping in one of their stores was like. They thought it was okay, and didn’t suck.

Even on short notice “unannounced” visits, somehow the store was tipped off, either by other local managers or by more junior flunkies of the regional managers, fearing for their own jobs if a shop was seen in disarray. Of course, overtime was rapidly offered, and 90% of the time you would take it because you wanted the money.

It seems that Morrisons’ management have picked up this behaviour along with a number of other bad habits from the Safeway acquisition.

One of my own pet hates is the way they build-out the aisle ends with free-standing stacks of items on promotion. This narrows the aisle width, reducing circulation area, and making it harder to manoeuvre your trolley, for fear of knocking over this teetering pile of products.

Obviously the idea is you take something from this wobbly pile to reduce it in size!

Tesco still aren’t much better. It’s a confusing environment of bright yellow price tags, contradictory “special non-offers”, and shouty shelf-edge “barkers”. It’s just a meh experience, and that’s after you’ve battled your way in past all the TVs, clothes and other crap they sell in the big stores.

Also, you’ve got to look if the business model is wrong? Are Morrisons working to a growth-centric business model? In a saturated market such as grocery shopping, the growth most likely has to come from stealing market share from a competitor. This likely comes with a higher cost of sale, as you’ve got to do something to make that fickle customer choose you today. Should Morrisons instead be looking after it’s own customers and working to a retention-based business model?

Rather than providing an unpleasant and stressful experience, do something to make your customers want to come back. You can’t compete on price alone or Aldi and Lidl will take your business away, and the niche high-ends are dominated by the likes of Waitrose and M&S.

I can’t help feeling that devouring Safeway was a meal that still gives Morrisons indigestion to this day, and they would maybe do better following Ken Morrison’s three simple tenets by which he ran the business for many years: good staff, good suppliers, loyal customers.

Read the BBC article and watch the interview with Ken Morrison

For peering in New York, read New Amsterdam

Dutch East India Company Logo
It’s colonialism all over again. Just not as we know it…

Last week, there was this announcement about the establishment of a new Internet Exchange point in New York by the US arm of the Amsterdam Internet Exchange – “AMS-IX New York” – or should that be “New Amsterdam”… 🙂

This follows on from the vote between AMS-IX members about whether or not the organisation should establish an operation in the US was carried by a fairly narrow majority. I wrote about this a few weeks ago.

This completes the moves by the “big three” European IX operators into the US market, arriving on US shores under the umbrella of the Open-IX initiative to increase market choice and competitiveness of interconnection in the US markets.

LINX have established LINX-NoVA in the Washington DC metro area, and AMS-IX are proceeding with their NY-NJ platform, while DECIX have issued a press statement on their plan to enter the NY market in due course.

One of the key things this does is bring these three IXPs into real direct competition in the same market territory for the first time.

There has always been some level of competition among the larger EU exchanges when attracting new international participants to their exchange, for instance DECIX carved itself a niche for attracting Eastern European and Russian players on account that many carrier services to these regions would hub through Frankfurt anyway.

But each exchange always had it’s indigenous home market to provide a constant base load of members, there wasn’t massive amounts of competition for the local/national peers, even though all three countries have a layer of smaller exchanges active in the home market.

Now, to some extent, they are going head-to-head, not just with US incumbents such as Equinix, TelX and Any2, but potentially with each other as well.

The other thing the AMS-IX move could end up doing is potentially fracture even further the NY peering market, which is already fractured – being served by three, maybe four, sizeable exchanges. Can it sustain a fifth or sixth?

Is it going to be economical for ISPs and Content Providers to connect to a further co-terminous IXP (or two)? Can the NY market support that? Does it make traffic engineering more complex for networks which interconnect in NY? So complex that it’s not worth it? Or does it present an opportunity to be able to more finely slice-and-dice traffic and share the load?

Don’t forget we’re also in a market which has been traditionally biased toward minimising the amount of public switch-based peering in favour of private bi-lateral cross-connects. Sure, the viewpoint is changing, but are we looking for a further swing in a long-term behaviour?

We found out from experience in the 2000s that London can only really sustain two IXPs – LINX and LONAP. There were at least 4 well-known IXPs in London in the 2000s, along with several smaller ones. (Aside… if you Google for LIPEX today, you get a link to a cholesterol-reducing statin drug.)

Going to locations on the East Coast may have made sense when we sailed there in ships and it took us several weeks to do it, but that’s no reason for history to repeat itself in this day and age, is it? So why choose New York now?

Will the EU players become dominant in these markets? Will they manage to help fractured markets such as NY to coalesce? If they do, they will have achieved something that people have been trying to do for years. Or, will it turn out to be an interesting experiment and learning experience?

It will be interesting to see how this plays out over time.

IX Scotland – Why might it work this time?

Yesterday the BBC ran this news item about the launch of a new Internet Exchange in Edinburgh – IX Scotland. This is the latest in an emerging trend of local IXPs developing in the UK, such as IX Leeds and IX Manchester.

There was some belief that this is the first Internet Exchange in Scotland, however those people have short memories. There have been two (or three) depending on how you look at it, attempts at getting a working IXP in Edinburgh in the past 15 years, all of which ultimately failed.

So, why should IX Scotland be any different to it’s predecessors? Continue reading “IX Scotland – Why might it work this time?”

BA’s Heathrow Lounge Food, Pt 2: The Lord of the Flies?

Following on from my recent post regarding a rather poor Environmental Health Report for BA’s “exclusive” Concorde Room, Hillingdon Council, the local authority responsible for Heathrow, have conducted further inspections of BA’s lounge operations at the airport.

This time, the largest lounge in T5, the “Galleries Club South” scored 2 out of 5, like it’s neighbour.

The report for this lounge highlights a number of basic food hygiene failings that seem to indicate a real lack of care.

Continue reading “BA’s Heathrow Lounge Food, Pt 2: The Lord of the Flies?”

My recent talk at INEX – Video

Or, I never thought of myself as a narcissist but…

Thanks to the folks at HEAnet, here’s a link to the video of the talk “It’s peering, Jim…” that I gave at the recent INEX meeting in Dublin, where I discuss topics such as changes in the US peering community thanks to Open-IX and try to untangle what people mean when they say “Regional Peering”.

The talk lasts around 20-25 minutes and I was really pleased to get around 15 minutes of questions at the end of it.

I also provide some fairly pragmatic advice to those seeking to start an IX in Northern Ireland during the questions. 🙂

mh_inex_video