Hi All - I am new to this mailer. Hopefully my question is posed to the
correct list.
I am using 2.5 Tbps as the peak volume of peering traffic over all peering
points for a Tier 1 ISP, for some modeling purposes. Is that a reasonable
estimate?
Thanks
Ravi
"Tier 1 ISP" is a nebulous term.
The top few networks in the world (not all of them are "tier 1 ISPs" - and one is not even a network 
are much larger. The smaller "tier 1s" are probably that size or less.
"Tier 1 ISP" is a nebulous term.
Indeed it is. See Peering - Wikipedia and Tier 1 network - Wikipedia for more information. I'm guessing you are using Tier 1 to refer to $LARGE_TELCOS (ATT/VZ/L3)
and I'm guessing their sustained daily traffic volume is well over 10tb.
The top few networks in the world (not all of them are "tier 1 ISPs" - and one is not even a network
Facebook and google probably push that much traffic daily. I used to work for a company that did 100Gbps sustained on a daily basis.
are much larger. The smaller "tier 1s" are probably that size or less.
I agree.
Possibly. The reason I say that is because the details of many ISPs' peering arrangements are often subject to NDA, so there is often a cone of silence around those bits.
jms
Hi All - I am new to this mailer. Hopefully my question is posed to the
correct list.
Welcome.
I am using 2.5 Tbps as the peak volume of peering traffic over all peering
points for a Tier 1 ISP, for some modeling purposes. Is that a reasonable
estimate?
That's actually a very difficult research question for the academic community, and one that they've been struggling with since they lost their overview of the NSFNET backbone in ~1992.
Ironically, it's quite easy for any one ISP to answer internally, but these numbers are closely held as trade-secrets.
One thing you can do is look at the total volume of publicly-reported traffic across IXP switch fabrics:
Internet Exchange Point Growth by Region | PCH
Internet Exchange Directory | PCH
…where you see about 8.3Tbps of overall reported traffic. Then you could do various analyses comparing IXPs where crossconnects are prevalent (Equinix Ashburn, say) to ones where they are not, and looking at which ISPs peer at each. You could also try to find out from ISPs which IXPs they use crossconnects at, and which they don't. That may be easier information for you to get than how much traffic they're doing individually.
It might also be interesting to look at some of the IXPs that publish per-participant traffic figures, to see if you can develop characteristic statistical distributions for amount-each-participant-contributes-to-the-IXP, though you should be cautioned that the curve might be much heavier-tailed for a large exchange than a small one.
Ultimately, if you're considering this as an academic research question, you may want to think about the utility of examining a "black box" question like this, when the answer is plainly known to other people, just not known to, or verifiable by, you. The chances of getting the answer "right" are low, and if you do get it "right" neither you nor your thesis advisor would ever find that out. There are many other classes of problem that are potentially much more rewarding, because they would contribute to our overall knowledge of how the network works: BGP route convergence and stability properties in chaotic (i.e. real-world) networks; documenting the performance and economic effects (and the tradeoff with stability) of denser peering meshes; study of the uptake of DNSSEC; study of the prevalence of different IPv4/IPv6 transition technologies...
-Bill
I am using 2.5 Tbps as the peak volume of peering traffic over all peering
points for a Tier 1 ISP, for some modeling purposes. Is that a reasonable
estimate?That's actually a very difficult research question for the academic community, and one that they've been struggling with since they lost their overview of the NSFNET backbone in ~1992.
Ironically, it's quite easy for any one ISP to answer internally, but these numbers are closely held as trade-secrets.
One thing you can do is look at the total volume of publicly-reported traffic across IXP switch fabrics:
Internet Exchange Point Growth by Region | PCH
Internet Exchange Directory | PCH
…where you see about 8.3Tbps of overall reported traffic. Then you could do various analyses comparing IXPs where crossconnects are prevalent (Equinix Ashburn, say) to ones where they are not, and looking at which ISPs peer at each. You could also try to find out from ISPs which IXPs they use crossconnects at, and which they don't. That may be easier information for you to get than how much traffic they're doing individually.
IXP vs. private interconnect (be it peering or customer/transit) ratios varies dramatically with geography, scale, and even the proclivities of the various network architects.
The question is whether "some data" is better than "no data". Honestly, I'm not sure. I see lots of things with 'some data' that are actually worse than guesses. But where I cannot eventually find the actual answer, I am left wanting to prefer the "some data" ones, probably because "data" sounds good.
It might also be interesting to look at some of the IXPs that publish per-participant traffic figures, to see if you can develop characteristic statistical distributions for amount-each-participant-contributes-to-the-IXP, though you should be cautioned that the curve might be much heavier-tailed for a large exchange than a small one.
Even that is dangerous. For instance, some participants move traffic away from such IXPs. (That is not a guess, I know first hand that this happens - especially as I am one of those people.)
The largest Tier 1's, like say Level 3, and god help me for saying it
but... Cogent, are certainly in or beyond that kind of ballpark. But
most of the smaller ones, like say AT&T, Qwest, ATDN (if you even still
want to count them), etc, not a chance in hell. And then there are
plenty of non tier 1 networks (and some that aren't even actual single
networks in the classic sense) that do far more traffic than that, for
example some of the large CDNs like Akamai and LimeLight.
On the modern Internet "most" of the traffic bypasses Tier 1 networks
completely, going directly from content networks to eyeball networks,
so the Tier 1's are effectively left as the higher priced and lower
capacity "last resorts" for the remaining traffic.
Yes, Patrick, I was just trying to be diplomatic about saying "not such a good idea" so he'd keep reading through to the end, where I suggested some other, possibly better, research topics. I am, however, certain that other people could suggest even better research topics. Good research topics are in demonstrably short supply among networking grad-students, so if y'all want to be helpful...
-Bill
