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[AFRINIC-rpd] IP Address / Wireless concurrency
owen at delong.com
Wed Oct 10 00:15:04 UTC 2012
Though 1.9:1 is probably a common ratio today, I would say that it will likely approach 3:1 in the reasonably foreseeable future.
However, it seems to me that this question relates only to a now antiquated addressing technology and becomes quite moot with current IPv6 addressing technology.
If you have a /64 and you have 5,000 students, you can support any ratio up to slightly more than 3,000,000,000,000,000 addresses per student. If you have more students, still not a problem. If you are attempting to support 1,000,000 students per subnet, this still leaves you room for more than 18,000,000,000,000 addresses per student.
Since it is physically impractical to support so many students per LAN segment with any foreseeable wireless technology, I think the question is moot for IPv6.
For IPv4, I would suggest that 3:1 is a good starting point today in terms of allocation policy and that by the time we exceed 3:1 real world statistics, IPv4 will likely be long since obsolete.
On Oct 9, 2012, at 9:10 AM, Andrew Alston <alston.networks at gmail.com> wrote:
> Hi Guys,
> Over the last few days one of the questions I have had to deal with when working with IP address applications surrounds concurrency of usage of networks. This is particularly relevant in the case of wireless networks, where space is being applied for and the infrastructure is not yet in place. I.E A particular institution has ordered a wireless network of a particular size, to serve a community of X number of users, from provider Y. The institution does not use NAT for various reasons that are out of scope of this discussion.
> Now, this raises some interesting questions, when motivating for IP space for this wireless network, how do you calculate potential IP concurrency for the network, and what guidance can we give to AfriNIC around the concurrency issue to help them as they process our applications. It's a curious question, but its become very clear to me in recent discussions that this is something that needs to be addressed.
> So, let me state what I have found in research I have done (I physically visited 3 universities in the last 2 days and spent a lot of time with them and looking at numbers they had). I openly state, in the cases of these universities, they were urban area institutions we were looking at, student base I would say would probably fall into the "middle class" category. (This is relevant considering other research which I will expand on).
> We found, in such institutions, particularly where individuals were required to authenticate to get access to the network, we were running at an average concurrency per individual on site of 1.9:1 addresses. Looking more closely, this was due to the smartphone prevalence (with at least 50% of leases in every case being smartphones), and the rest being a balance of notebooks/ipads/android tablets etc.
> The concurrency of leases dropped significantly when looking at data surrounding more rural institutions, however, the smartphone prevalence remained, and the ratio was consistently over 1:1 per people in range of a wireless AP.
> So, before I write further, my question to all of you that are running wireless networks, what sort of address concurrency are you seeing, and what are the stats you can provide so that we can look at some sort of uniform way in which to address this question in the applications process.
> Of course, that also raises the question (particularly relevant on a university campus), about concurrent numbers of people on campus. In an institution with 45 thousand full time students, what percentage of those people are on campus at any one time. Currently, in initial (and albeit very brief) research, we're seeing this at around 80% at peak (and on wireless to avoid running out of leases, peak is what you are catering for). I'll send some more research data back on this once and if we manage to gain firm figures (these figures will be gained by looking at universities who run access control onto campus and we can look at the access control to get figures). Again, I'd be interesting in hearing from others here involved in these types of networks what stats they have.
> As a matter of interest, by our calculations, on a university campus with 50 thousand people (5 thousand staff, 45 thousand students), with 100% wireless coverage, we hit an ip address assignment concurrency calculation of 76 thousand addresses on the wireless with current data that is still being expanded.
> For the purposes of this discussion and to avoid going off topic, please, let us avoid the debates about NAT on wireless networks and other such things, I am merely looking at the discussion of IP address concurrency.
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