[NNagain] transit and peering costs projections

[Jack Haverty]

The "VGV User" (Voice, Gaming, Videoconferencing) cares a lot about 
latency.   It's not just "rewarding" to have lower latencies; high 
latencies may make VGV unusable.   Average (or "typical") latency as the 
FCC label proposes isn't a good metric to judge usability.  A path which 
has high variance in latency can be unusable even if the average is 
quite low.   Having your voice or video or gameplay "break up" every 
minute or so when latency spikes to 500 msec makes the "user experience" 
intolerable.

A few years ago, I ran some simple "ping" tests to help a friend who was 
trying to use a gaming app.  My data was only for one specific path so 
it's anecdotal.  What I saw was surprising - zero data loss, every 
datagram was delivered, but occasionally a datagram would take up to 30 
seconds to arrive.  I didn't have the ability to poke around inside, but 
I suspected it was an experience of "bufferbloat", enabled by the 
dramatic drop in price of memory over the decades.

It's been a long time since I was involved in operating any part of the 
Internet, so I don't know much about the inner workings today. Apologies 
for my ignorance....

There was a scenario in the early days of the Internet for which we 
struggled to find a technical solution.  Imagine some node in the bowels 
of the network, with 3 connected "circuits" to some other nodes.  On two 
of those inputs, traffic is arriving to be forwarded out the third 
circuit.  The incoming flows are significantly more than the outgoing 
path can accept.

What happens?   How is "backpressure" generated so that the incoming 
flows are reduced to the point that the outgoing circuit can handle the 
traffic?

About 45 years ago, while we were defining TCPV4, we struggled with this 
issue, but didn't find any consensus solutions.  So "placeholder" 
mechanisms were defined in TCPV4, to be replaced as research continued 
and found a good solution.

In that "placeholder" scheme, the "Source Quench" (SQ) IP message was 
defined; it was to be sent by a switching node back toward the sender of 
any datagram that had to be discarded because there wasn't any place to 
put it.

In addition, the TOS (Type Of Service) and TTL (Time To Live) fields 
were defined in IP.

TOS would allow the sender to distinguish datagrams based on their 
needs.  For example, we thought "Interactive" service might be needed 
for VGV traffic, where timeliness of delivery was most important.  
"Bulk" service might be useful for activities like file transfers, 
backups, et al.   "Normal" service might now mean activities like using 
the Web.

The TTL field was an attempt to inform each switching node about the 
"expiration date" for a datagram.   If a node somehow knew that a 
particular datagram was unlikely to reach its destination in time to be 
useful (such as a video datagram for a frame that has already been 
displayed), the node could, and should, discard that datagram to free up 
resources for useful traffic.  Sadly we had no mechanisms for measuring 
delay, either in transit or in queuing, so TTL was defined in terms of 
"hops", which is not an accurate proxy for time.   But it's all we had.

Part of the complexity was that the "flow control" mechanism of the 
Internet had put much of the mechanism in the users' computers' TCP 
implementations, rather than the switches which handle only IP. Without 
mechanisms in the users' computers, all a switch could do is order more 
circuits, and add more memory to the switches for queuing.  Perhaps that 
led to "bufferbloat".

So TOS, SQ, and TTL were all placeholders, for some mechanism in a 
future release that would introduce a "real" form of Backpressure and 
the ability to handle different types of traffic.   Meanwhile, these 
rudimentary mechanisms would provide some flow control. Hopefully the 
users' computers sending the flows would respond to the SQ backpressure, 
and switches would prioritize traffic using the TTL and TOS information.

But, being way out of touch, I don't know what actually happens today.  
Perhaps the current operators and current government watchers can answer?:

1/ How do current switches exert Backpressure to  reduce competing 
traffic flows?  Do they still send SQs?

2/ How do the current and proposed government regulations treat the 
different needs of different types of traffic, e.g., "Bulk" versus 
"Interactive" versus "Normal"?  Are Internet carriers permitted to treat 
traffic types differently?  Are they permitted to charge different 
amounts for different types of service?

Jack Haverty

On 10/15/23 09:45, Dave Taht via Nnagain wrote:
> For starters I would like to apologize for cc-ing both nanog and my
> new nn list. (I will add sender filters)
>
> A bit more below.
>
> On Sun, Oct 15, 2023 at 9:32 AM Tom Beecher <beecher at beecher.cc> wrote:
>>> So for now, we'll keep paying for transit to get to the others (since it’s about as much as transporting IXP from Dallas), and hoping someone at Google finally sees Houston as more than a third rate city hanging off of Dallas. Or… someone finally brings a worthwhile IX to Houston that gets us more than peering to Kansas City. Yeah, I think the former is more likely. 😊
>>
>> There is often a chicken/egg scenario here with the economics. As an eyeball network, your costs to build out and connect to Dallas are greater than your transit cost, so you do that. Totally fair.
>>
>> However think about it from the content side. Say I want to build into to Houston. I have to put routers in, and a bunch of cache servers, so I have capital outlay , plus opex for space, power, IX/backhaul/transit costs. That's not cheap, so there's a lot of calculations that go into it. Is there enough total eyeball traffic there to make it worth it? Is saving 8-10ms enough of a performance boost to justify the spend? What are the long term trends in that market? These answers are of course different for a company running their own CDN vs the commercial CDNs.
>>
>> I don't work for Google and obviously don't speak for them, but I would suspect that they're happy to eat a 8-10ms performance hit to serve from Dallas , versus the amount of capital outlay to build out there right now.
> The three forms of traffic I care most about are voip, gaming, and
> videoconferencing, which are rewarding to have at lower latencies.
> When I was a kid, we had switched phone networks, and while the sound
> quality was poorer than today, the voice latency cross-town was just
> like "being there". Nowadays we see 500+ms latencies for this kind of
> traffic.
>
> As to how to make calls across town work that well again, cost-wise, I
> do not know, but the volume of traffic that would be better served by
> these interconnects quite low, respective to the overall gains in
> lower latency experiences for them.
>
>
>
>> On Sat, Oct 14, 2023 at 11:47 PM Tim Burke <tim at mid.net> wrote:
>>> I would say that a 1Gbit IP transit in a carrier neutral DC can be had for a good bit less than $900 on the wholesale market.
>>>
>>> Sadly, IXP’s are seemingly turning into a pay to play game, with rates almost costing as much as transit in many cases after you factor in loop costs.
>>>
>>> For example, in the Houston market (one of the largest and fastest growing regions in the US!), we do not have a major IX, so to get up to Dallas it’s several thousand for a 100g wave, plus several thousand for a 100g port on one of those major IXes. Or, a better option, we can get a 100g flat internet transit for just a little bit more.
>>>
>>> Fortunately, for us as an eyeball network, there are a good number of major content networks that are allowing for private peering in markets like Houston for just the cost of a cross connect and a QSFP if you’re in the right DC, with Google and some others being the outliers.
>>>
>>> So for now, we'll keep paying for transit to get to the others (since it’s about as much as transporting IXP from Dallas), and hoping someone at Google finally sees Houston as more than a third rate city hanging off of Dallas. Or… someone finally brings a worthwhile IX to Houston that gets us more than peering to Kansas City. Yeah, I think the former is more likely. 😊
>>>
>>> See y’all in San Diego this week,
>>> Tim
>>>
>>> On Oct 14, 2023, at 18:04, Dave Taht <dave.taht at gmail.com> wrote:
>>>> This set of trendlines was very interesting. Unfortunately the data
>>>> stops in 2015. Does anyone have more recent data?
>>>>
>>>> https://drpeering.net/white-papers/Internet-Transit-Pricing-Historical-And-Projected.php
>>>>
>>>> I believe a gbit circuit that an ISP can resell still runs at about
>>>> $900 - $1.4k (?) in the usa? How about elsewhere?
>>>>
>>>> ...
>>>>
>>>> I am under the impression that many IXPs remain very successful,
>>>> states without them suffer, and I also find the concept of doing micro
>>>> IXPs at the city level, appealing, and now achievable with cheap gear.
>>>> Finer grained cross connects between telco and ISP and IXP would lower
>>>> latencies across town quite hugely...
>>>>
>>>> PS I hear ARIN is planning on dropping the price for, and bundling 3
>>>> BGP AS numbers at a time, as of the end of this year, also.
>>>>
>>>>
>>>>
>>>> --
>>>> Oct 30: https://netdevconf.info/0x17/news/the-maestro-and-the-music-bof.html
>>>> Dave Täht CSO, LibreQos
>
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