On network utilization

[JF Amiot]

Hello, I received a question from one of our member asking how our network utilization compares with traditional ISPs after reading this excerpt:

"First, modern ISPs run their networks at a relatively low utilization

[18, 21, 26]. This is not because ISPs are in- capable of achieving

higher utilization, but because their networks must be prepared for

link failures which could, at any time, reduce their available

capacity by a significant fraction. Thus, most ISP networks are

engineered with substantial headroom,"

Here's the answer for this tech radar post: 

First, I have to say that I have never worked for an ISP directly, but know many people who have been in the industry.

I think it's a question of degree. ISPs, as they are driven by profits, try to run their network in the sweet spot, so their utilization could be considered low for some, but they will naturally try to aggregate where they can. It also depends on their topology and technology roll out (Many ISPs, including SHAW recently upgraded their core to 100Gbps, so I doubt they are short of capacity on the backbone.)  It also depends if one consider only the upstreams (In most case, we plan for lots of redundancy, so low utilization) or backbone network where some links could see high utilization.

In the R&E world it's very different because we typically carry 2 types of traffic, R&E is very bursty by nature, so we absolutely need the headroom.  Average utilization could be relatively low over a long period. And again, the motivation is different from an ISP. We of course strive to build in as much redundancy as we can, but Canarie is essentially a best effort network with no binding SLAs.  The headroom is absolutely necessary for research to happen. We also do not use QOS as we believe the best way to deliver traffic in the fist place is to have sufficient capacity to deliver every packets without policing what is allowed to go through. 

On the commodity Internet side, we have constant flows and the traffic is not busty at all. So we can attain more aggregation without needing to upgrade capacity.  But overall, we purchase 5 Gig from our upstreams and really use about 2, so lots of spare capacity that is needed when one of the Internet upstream go down.

And on the ISP side, they will over provision at the local level, (a street access point could share a fixed amount of bandwidth - DOCSIS technology ) so utilization could run very high at that level, but not necessarily going up from there.

Of course, if you ask CANARIE, the answer would be different from ISPs as Canarie does not carry commodity Internet at all. So it's hard to have a fair comparison as both the motivations and the characteristic of the traffic is very different.

Hope this helps understand the R&E network landscape and how it relate to utilization.

Jean-Francois Amiot

Network & Operations Director

Cybera Inc.  <http://www.cybera.ca>

Tel (403) 210-5314

Cell: (403) 973-1767

Cybera is a not-for-profit organization that works to spur and support innovation, for the economic benefit of Alberta, through the use of cyberinfrastructure.

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