[NNagain] transit and peering costs projections

[Sebastian Moeller]

Hi Jack,

> On Oct 15, 2023, at 21:59, Jack Haverty via Nnagain <nnagain at lists.bufferbloat.net> wrote:
> 
> 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?

	[SM] As far as i can tell SQ is considered a "failed" experiment at least over the open internet, as anybody can manufacture such quench messages and hence these pose an excellent DOS vector. In controlled environments however this idea keeps coming back (as it has the potential for faster signaling than piggy-backing a signal onto the forward packets and expect the receiver to reflect the signals back to the sender). But instead over the internet we have the receivers detect either packet drops or explicit signals of congestion (ECN or alternatives) and reflect these back to the senders that are then expected to respond appropriately*. The congested nodes really only can drop and/or use some sort of clever scheduling to not spread the overload on all connections but if push comes to shove dropping is really the only option, in your example if two ingress interfaces converge on a single egress interface of half the capacity, as long as the aggregate ingress rate exceeds the egress rate queues will grow and once these reached an end all the node can do is drop ingressing packets...

*) With lots of effort put into responding as gently as possible, not sure that from a perspective of internet stability we would not fare better with a strict "on congestion detection at least half the sending rate" mandate and a way to enforce that... but then I am not a CS or network expert, so what do I know.


> 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?

	[SM] I can only talk about the little I know about EU regulations; conceptually an ISP is to treat all traffic to/from its end-customers equally. But the ISP is free to use any king of service level agreement (SLA) with its upstreams*. They also can offer special services with other properties but not as premium internet access service. However if an ISP offers some QoS treatment configurable by its end-users that would IMHO by fair game... the main goal here is to avoid having the ISPs picking winners and losers in regards to content providers, end-users are free to do so if they wish. IMHO an ISP offering QoS services (opt-in and controlled by the end-user) might as well charge extra for that service. They are also permitted to charge differently based on access capacity (vulgo "speed") and extras (like fixed-line and/or mobile telephony volumes or flat rates).

*) As long as that does not blatantly affect the unbiased internet access by the ISPs end-users, that is a bit of a gray zone that current EU regulations carefully step around. I Think ISPs do this e.g. for their own VoIP traffic, and regulators and end-users generally seem to agree that working telephony is somewhat important. Net neutrality regulations really only demand that such a special treatment would be available to all VoIP traffic and not just the ISPs, but at least over here nobody seems to be fighting for this right now. Then again people generally also seem to be happy with 3rd party VoIP, what ever this means.

Regards
	Sebastian


> 
> 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
>> 
>> 
> 
> _______________________________________________
> Nnagain mailing list
> Nnagain at lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/nnagain