nanog mailing list archives
Re: Contention/Oversubscription maths
From: Adam Armstrong <lists () memetic org>
Date: Fri, 27 May 2011 14:01:46 +0100
On 27/05/2011 13:45, Jared Mauch wrote:
This results in people complaining *about* us, as the crappy performance of 802.11g made a lot of people complain about ADSL2+ ISPs (because G can't really do 24Mbit!)On May 27, 2011, at 8:14 AM, Adam Armstrong wrote:No SLA, residential customers.I would watch out for the 'abusers' in this case, and have the capability to rate-limit the ports if necessary. Some hardware doesn't deal well with 'small' buckets of rate-limiting, eg: taking a 1G port to 1M. I'm interested in your operational results, as i've had a few general ASSumptions i've offered in this space: - Most people are going to be limited by their wireless gear (few people care to run wired very far)
This holds true until you look at services delivered by farms, such as Akamai, Usenet or P2P. I'd be interested to see what happens with 1000 people with 1000Mbit services start torrenting the next major HD movie release.- Most servers on the far-end aren't going to be fast enough to cope
- Most people aren't going to spend time debugging network problems
Indeed, they just moan about us instead :(
Policing isn't something we want to do (other than to police 100Mbit ports to 20Mbit for those who buy the 20Mbit product. Policing is against the ethos of the company.)- Some percentage of users are going to run a torrent or something else and flatline their port. You need to be able to police them at a reasonable bandwidth cap, eg: 10M if they have 1G, but that's 1% and many dumber switches won't go under 10%.
This what i see elsewhere in buildings with similar mixes of customers as we're expecting. For example in a building with ~1000 2-100Mbit customers a single 100mbit customer can pretty much double the peak traffic usage of a building if they decide to download a lot.The other solution is to just throw more bandwidth at the problem. Make sure your switches can easily take a 10G or n*10G uplink. I'd expect that the single bursty user is going to drown out the rest of them into the noise, as they will likely plug in directly and have no wireless hops that limit their speeds.
One of my friends operates a WISP in this area and has periodic issues with the heavy usage users and wonders what they're doing with that 150GB of data they "download" in a month.
I've been known to download ~1.5TB in month on my 24Mbit ADSL service.It's people like *me* that I'm worried about. Our deployment model means that individual customers can't chose us, we chose which buildings we connect and then are likely to get most people within that building, so I'm hoping our hoggers should be fairly spread out. Though, I'm sure this won't be the case as certain areas of the city are likely to have more of each specific kinds of network user.
Our upgrade plans include 10GE to buildings when the building has a large number of occupants (>1000), but before then it's cost prohibitive.
adam.
Current thread:
- Re: Contention/Oversubscription maths, (continued)
- Re: Contention/Oversubscription maths Valdis . Kletnieks (May 26)
- Re: Contention/Oversubscription maths Dobbins, Roland (May 26)
- Re: Contention/Oversubscription maths Adam Armstrong (May 27)
- Re: Contention/Oversubscription maths Valdis . Kletnieks (May 27)
- Message not available
- Re: Contention/Oversubscription maths Adam Armstrong (May 27)
- RE: Contention/Oversubscription maths Frank Bulk (May 27)
- Re: Contention/Oversubscription maths Dobbins, Roland (May 26)
- Re: Contention/Oversubscription maths Jay Ashworth (May 27)
- Re: Contention/Oversubscription maths Adam Armstrong (May 27)
- Re: Contention/Oversubscription maths Valdis . Kletnieks (May 26)
- Re: Contention/Oversubscription maths Jared Mauch (May 27)
- Re: Contention/Oversubscription maths Adam Armstrong (May 27)
- Re: Contention/Oversubscription maths Adam Armstrong (May 27)
- Re: Contention/Oversubscription maths Jacob Broussard (May 27)
- Re: Contention/Oversubscription maths Adam Armstrong (May 27)
- Re: Contention/Oversubscription maths Jay Ashworth (May 27)
- Re: Contention/Oversubscription maths Shaun Bryant (May 27)
- Re: Contention/Oversubscription maths Adam Armstrong (May 27)