8 ms·

> The comment submitted by Dave Taht, chief science officer of LibreQoS, argues that today’s applications are not typically bandwidth-limited, but are instead s

by vitus 3y ago

> The comment submitted by Dave Taht, chief science officer of LibreQoS, argues that today’s applications are not typically bandwidth-limited, but are instead significantly limited by working latency. (for reference, Taht's comment is indirectly linked from the submission; https://www.fcc.gov/ecfs/document/12010651418616/1 https://www.fcc.gov/ecfs/document/12010651418616/1 which has much more detailed technical discussion.) Dave Taht... that's the guy behind a lot of the bufferbloat work over the past decade or so (and seems to be the submitter?), right? In my experience, predictable latency is more important than low latency. 50ms RTT can be fine for a video call; it's not fine if it spikes up to 500ms sporadically. Protocol work like QUIC that can reduce per-connection startup overhead definitely helps in this regard. On the other hand, if you have a highly interactive use case like SSH where every single keystroke must roundtrip between you and a server, that 50ms RTT is very visible. I think talking about absolute latency might be misguided in that it depends partially on the other end you're talking to. If I'm in the eastern US and communicating to a server in India, there's no way I'm getting < 100ms RTT (I'd be happy if I could get 200ms). On the other hand, if you're using legacy satellite internet like Viasat you might have 600ms latency talking to a server in the same city. (Starlink does better, but it still imposes sizable fixed latency costs on the order of 10s of ms.) If I had to come up with latency metrics, I might initially suggest "< 20ms within the same city; loaded latency must not impose a penalty greater than 40ms" (I'd love for these numbers to be lower, but they're already very ambitious for Starlink due to physical characteristics of the satellite constellation). edit: of course, in retrospect, that's my urban bias coming through -- what if you don't live in a city? or consider Hawaii -- is it good enough to just consider latency to Honolulu? Or do you want latency to www.google.com (the nearest frontends are in Los Angeles)?

acje 3y ago
Having thought about this today and read some responses here, my best proposal would be to require endpoints available for the FCC to measure and then just create a service to show the results. That would give so many more vectors of improvement over time. How to measure, report such that users understand, capture change over time. No mater what number one puts on a label, that number will likely become misleading over time.
bluGill 3y ago
If latency is consistent you get used to it and learn to deal with it. Improving latency would improve your quality of life, but you often won't realize it. I don't need the ssh to show the character I just typed instantly so long as the characters get there eventually in the right order. I don't need my bank's webpage to show my balance instantly. However if latency is not consistent I will notice as I've already learned how long those things "should" take.
- Arrath 3y ago
  > If latency is consistent you get used to it and learn to deal with it. Too true. I played so much WoW on 56k that when I finally moved into an area that had high speed internet I basically had to learn to play all over again. IE stop compensating for pings in the ~300ms range.
- dtaht 3y ago
  Mosh, over wifi, is a sanity saver.
dtaht 3y ago
Consistently low latency is great. Not just with bufferbloat but with physical latency. A lot of city-based fiber dwellers think that just running fiber out to rural areas actually improves performance more than it does. Moving data and interconnectivity out there helps more. They really should get out more. Or, perhaps, learn how to insert artificial, rural like delays into their networks in the city, to grok it. (I am very busy today at the metro connect conference in ft lauderdale today, please expect sparse replies if any. If any of y'all are actually here today, I am outside with Bandwidth is a lie t-shirt on!
- vitus 3y ago
  Oh, I absolutely believe this. My example of Hawaii being 70ms away from Google was something that I knew about on paper but didn't truly appreciate until I was there on vacation a few years back (where the hotel wifi injected another 30-50ms on unloaded connections). Moving interconnectivity to rural areas is tricky because most peering is where you can convince other network operators to meet you. This is a bit of a catch-22, where if you're not big enough then most network operators won't bother, and you can't get big enough unless you get these network operators on board. There's a secondary issue where just having peering isn't useful without servers (or vice versa), and you often don't have the economies of scale to justify spending millions on routing equipment, servers, etc. if you don't expect to serve many users there. The compromise that some of these big operators (Google, Facebook, Netflix off the top of my head) make is to install cache nodes inside ISP deployments for last-mile delivery. My understanding is that this is generally a win-win for all parties involved: ISPs don't have to build out as much backbone / peering capacity, Google and co can get away with smaller deployments and piggyback off of the ISP's existing network presence, and end users have better quality of experience. That said, for the most part, Google's cache nodes don't serve www.google.com because we generally view them as less secure, and we would have a very bad day if we had a compromise of any high-value TLS certs. (We mostly use them to serve YouTube videos, since that's where we derive the most value from bandwidth offload.)
- Dylan16807 3y ago
  Please explain how you get a high latency on fiber that doesn't involve bufferbloat or doing something purposefully wrong. Where are these rural delays coming from? Especially because an extra 200 miles of fiber only increases round trip time by 3 milliseconds. How far are signals going before they get routed in the right direction?

by vitus 3y ago

acje 3y ago

Having thought about this today and read some responses here, my best proposal would be to require endpoints available for the FCC to measure and then just create a service to show the results. That would give so many more vectors of improvement over time. How to measure, report such that users understand, capture change over time. No mater what number one puts on a label, that number will likely become misleading over time.

bluGill 3y ago

If latency is consistent you get used to it and learn to deal with it. Improving latency would improve your quality of life, but you often won't realize it. I don't need the ssh to show the character I just typed instantly so long as the characters get there eventually in the right order. I don't need my bank's webpage to show my balance instantly. However if latency is not consistent I will notice as I've already learned how long those things "should" take.

Arrath 3y ago
> If latency is consistent you get used to it and learn to deal with it. Too true. I played so much WoW on 56k that when I finally moved into an area that had high speed internet I basically had to learn to play all over again. IE stop compensating for pings in the ~300ms range.
dtaht 3y ago
Mosh, over wifi, is a sanity saver.

dtaht 3y ago

Consistently low latency is great. Not just with bufferbloat but with physical latency. A lot of city-based fiber dwellers think that just running fiber out to rural areas actually improves performance more than it does. Moving data and interconnectivity out there helps more. They really should get out more. Or, perhaps, learn how to insert artificial, rural like delays into their networks in the city, to grok it. (I am very busy today at the metro connect conference in ft lauderdale today, please expect sparse replies if any. If any of y'all are actually here today, I am outside with Bandwidth is a lie t-shirt on!

vitus 3y ago
Oh, I absolutely believe this. My example of Hawaii being 70ms away from Google was something that I knew about on paper but didn't truly appreciate until I was there on vacation a few years back (where the hotel wifi injected another 30-50ms on unloaded connections). Moving interconnectivity to rural areas is tricky because most peering is where you can convince other network operators to meet you. This is a bit of a catch-22, where if you're not big enough then most network operators won't bother, and you can't get big enough unless you get these network operators on board. There's a secondary issue where just having peering isn't useful without servers (or vice versa), and you often don't have the economies of scale to justify spending millions on routing equipment, servers, etc. if you don't expect to serve many users there. The compromise that some of these big operators (Google, Facebook, Netflix off the top of my head) make is to install cache nodes inside ISP deployments for last-mile delivery. My understanding is that this is generally a win-win for all parties involved: ISPs don't have to build out as much backbone / peering capacity, Google and co can get away with smaller deployments and piggyback off of the ISP's existing network presence, and end users have better quality of experience. That said, for the most part, Google's cache nodes don't serve www.google.com because we generally view them as less secure, and we would have a very bad day if we had a compromise of any high-value TLS certs. (We mostly use them to serve YouTube videos, since that's where we derive the most value from bandwidth offload.)
Dylan16807 3y ago
Please explain how you get a high latency on fiber that doesn't involve bufferbloat or doing something purposefully wrong. Where are these rural delays coming from? Especially because an extra 200 miles of fiber only increases round trip time by 3 milliseconds. How far are signals going before they get routed in the right direction?