极度怀疑comcast的限速# EmergingNetworking - 热门网络技术
j*a
1 楼
6m/384k的cable线路，我放了qos，上传不超过260k但还是慢得要死
发现似乎大概230pps的时候浏览就很大延迟了
极度怀疑还做了包限制
发现似乎大概230pps的时候浏览就很大延迟了
极度怀疑还做了包限制
z*r
2 楼
1. the service is up to xxxbps/yyybps, not guaranteed
2. where do you deploy the QoS? on your pc? then you should count the
network link headers, because the 384kbps is for the network speed instead
of payload
【在 j*a 的大作中提到】
: 6m/384k的cable线路，我放了qos，上传不超过260k但还是慢得要死
: 发现似乎大概230pps的时候浏览就很大延迟了
: 极度怀疑还做了包限制
2. where do you deploy the QoS? on your pc? then you should count the
network link headers, because the 384kbps is for the network speed instead
of payload
【在 j*a 的大作中提到】
: 6m/384k的cable线路，我放了qos，上传不超过260k但还是慢得要死
: 发现似乎大概230pps的时候浏览就很大延迟了
: 极度怀疑还做了包限制
o*y
3 楼
我也遇到过这个问题。在自家测试，网速应该是6Mbps/1.5Mbps. 上传一开始可以达到1
.5Mbps,接着跳回350Kbps，伴随着巨大延迟。
这里有没有人知道Cable access network 的构造？
.5Mbps,接着跳回350Kbps，伴随着巨大延迟。
这里有没有人知道Cable access network 的构造？
z*r
4 楼
comcast 6m/1.5m? you kidding, when I was using comcast, my downstream is 16M
, but the upstream is only 1M. For your regular 6M downstream speed, your
upstream is 384k.
到1
【在 o*********y 的大作中提到】
: 我也遇到过这个问题。在自家测试，网速应该是6Mbps/1.5Mbps. 上传一开始可以达到1
: .5Mbps,接着跳回350Kbps，伴随着巨大延迟。
: 这里有没有人知道Cable access network 的构造？
, but the upstream is only 1M. For your regular 6M downstream speed, your
upstream is 384k.
到1
【在 o*********y 的大作中提到】
: 我也遇到过这个问题。在自家测试，网速应该是6Mbps/1.5Mbps. 上传一开始可以达到1
: .5Mbps,接着跳回350Kbps，伴随着巨大延迟。
: 这里有没有人知道Cable access network 的构造？
o*y
5 楼
I can even reach 30Mbps down, 1.5Mbps up for a short while (ten seconds or
longer). The upload rate got cut back to 370Kbps after a while, the download
rate got cut to below 10Mbps similar.
Not sure what kind of device Comcast uses to meter and shape traffic.
16M
【在 z**r 的大作中提到】
: comcast 6m/1.5m? you kidding, when I was using comcast, my downstream is 16M
: , but the upstream is only 1M. For your regular 6M downstream speed, your
: upstream is 384k.
:
: 到1
longer). The upload rate got cut back to 370Kbps after a while, the download
rate got cut to below 10Mbps similar.
Not sure what kind of device Comcast uses to meter and shape traffic.
16M
【在 z**r 的大作中提到】
: comcast 6m/1.5m? you kidding, when I was using comcast, my downstream is 16M
: , but the upstream is only 1M. For your regular 6M downstream speed, your
: upstream is 384k.
:
: 到1
z*r
6 楼
how did you measure the speed? from what you said, I can tell that you got
influenced by the cache.
let me guess how you measured the speed, I guess you used web browser? when
you click downloading, you usually get a chance to select where to store the
file, at this moment, the clock is not starting yet, but the background
downloading has been started. That's why you could see a fast speed in the
very beginning.
In addtion, no matter what kind of shaping comcast used, it IS shaping. How
shaping
【在 o*********y 的大作中提到】
: I can even reach 30Mbps down, 1.5Mbps up for a short while (ten seconds or
: longer). The upload rate got cut back to 370Kbps after a while, the download
: rate got cut to below 10Mbps similar.
: Not sure what kind of device Comcast uses to meter and shape traffic.
:
: 16M
influenced by the cache.
let me guess how you measured the speed, I guess you used web browser? when
you click downloading, you usually get a chance to select where to store the
file, at this moment, the clock is not starting yet, but the background
downloading has been started. That's why you could see a fast speed in the
very beginning.
In addtion, no matter what kind of shaping comcast used, it IS shaping. How
shaping
【在 o*********y 的大作中提到】
: I can even reach 30Mbps down, 1.5Mbps up for a short while (ten seconds or
: longer). The upload rate got cut back to 370Kbps after a while, the download
: rate got cut to below 10Mbps similar.
: Not sure what kind of device Comcast uses to meter and shape traffic.
:
: 16M
o*y
7 楼
Thanks for the explanation. Nope, I did not use web browser to test speed, though I know of such tools, e.g, speedtest.net. What I used was a simple program that sends UDP at a
constant bit rate to a receiver; the receiver reports the measured
throughput.
I suspect Comcast uses devices similar to token bucket to police traffic from home users, and shape out-of-profile traffic at a hard limit, e.g., 6Mbps/370Kbps. Simply my guess, no solid evidence at all.
when
the
How
won'
between
【在 z**r 的大作中提到】
: how did you measure the speed? from what you said, I can tell that you got
: influenced by the cache.
: let me guess how you measured the speed, I guess you used web browser? when
: you click downloading, you usually get a chance to select where to store the
: file, at this moment, the clock is not starting yet, but the background
: downloading has been started. That's why you could see a fast speed in the
: very beginning.
: In addtion, no matter what kind of shaping comcast used, it IS shaping. How
: shaping
constant bit rate to a receiver; the receiver reports the measured
throughput.
I suspect Comcast uses devices similar to token bucket to police traffic from home users, and shape out-of-profile traffic at a hard limit, e.g., 6Mbps/370Kbps. Simply my guess, no solid evidence at all.
when
the
How
won'
between
【在 z**r 的大作中提到】
: how did you measure the speed? from what you said, I can tell that you got
: influenced by the cache.
: let me guess how you measured the speed, I guess you used web browser? when
: you click downloading, you usually get a chance to select where to store the
: file, at this moment, the clock is not starting yet, but the background
: downloading has been started. That's why you could see a fast speed in the
: very beginning.
: In addtion, no matter what kind of shaping comcast used, it IS shaping. How
: shaping
z*r
8 楼
you need to find a better way to test the speed. what you said doesn't make
sense.
read my previous post, you can see comcast uses shaping for downstream
traffic, this is a must for any provider to limit the rate.
though I know of such tools, e.g, speedtest.net. What I used was a simple
program that sends UDP at a
from home users, and shape out-of-profile traffic at a hard limit, e.g.,
6Mbps/370Kbps. Simply my guess, no solid evidence at all.
【在 o*********y 的大作中提到】
: Thanks for the explanation. Nope, I did not use web browser to test speed, though I know of such tools, e.g, speedtest.net. What I used was a simple program that sends UDP at a
: constant bit rate to a receiver; the receiver reports the measured
: throughput.
: I suspect Comcast uses devices similar to token bucket to police traffic from home users, and shape out-of-profile traffic at a hard limit, e.g., 6Mbps/370Kbps. Simply my guess, no solid evidence at all.
:
: when
: the
: How
: won'
: between
sense.
read my previous post, you can see comcast uses shaping for downstream
traffic, this is a must for any provider to limit the rate.
though I know of such tools, e.g, speedtest.net. What I used was a simple
program that sends UDP at a
from home users, and shape out-of-profile traffic at a hard limit, e.g.,
6Mbps/370Kbps. Simply my guess, no solid evidence at all.
【在 o*********y 的大作中提到】
: Thanks for the explanation. Nope, I did not use web browser to test speed, though I know of such tools, e.g, speedtest.net. What I used was a simple program that sends UDP at a
: constant bit rate to a receiver; the receiver reports the measured
: throughput.
: I suspect Comcast uses devices similar to token bucket to police traffic from home users, and shape out-of-profile traffic at a hard limit, e.g., 6Mbps/370Kbps. Simply my guess, no solid evidence at all.
:
: when
: the
: How
: won'
: between
o*y
9 楼
Shaping is certainly used, but is it for per-user or per-group? Is it the
same for home user or for business accounts? Will there be any interaction
between traffic from different users?
Except for Comcast engineers, probably seldom anyone else knows the details
of how they enforce bandwidth. I was trying to apply some "black-box" testings, but
obviously it cannot give me enough information. I was hoping to get some
more precise information from people who know cable technology very well, or
fro
【在 z**r 的大作中提到】
: you need to find a better way to test the speed. what you said doesn't make
: sense.
: read my previous post, you can see comcast uses shaping for downstream
: traffic, this is a must for any provider to limit the rate.
:
: though I know of such tools, e.g, speedtest.net. What I used was a simple
: program that sends UDP at a
: from home users, and shape out-of-profile traffic at a hard limit, e.g.,
: 6Mbps/370Kbps. Simply my guess, no solid evidence at all.
same for home user or for business accounts? Will there be any interaction
between traffic from different users?
Except for Comcast engineers, probably seldom anyone else knows the details
of how they enforce bandwidth. I was trying to apply some "black-box" testings, but
obviously it cannot give me enough information. I was hoping to get some
more precise information from people who know cable technology very well, or
fro
【在 z**r 的大作中提到】
: you need to find a better way to test the speed. what you said doesn't make
: sense.
: read my previous post, you can see comcast uses shaping for downstream
: traffic, this is a must for any provider to limit the rate.
:
: though I know of such tools, e.g, speedtest.net. What I used was a simple
: program that sends UDP at a
: from home users, and shape out-of-profile traffic at a hard limit, e.g.,
: 6Mbps/370Kbps. Simply my guess, no solid evidence at all.
z*r
10 楼
you don't have to be a comcast employee to get all this info, there is a
term called standard. I agree each company may treak a little bit, but
basically they follow the same or similar standard.
usually it's per-user basis, not only shaping, also guaranteed bandwidth.
That's why queuing function is so important for access equipment. It's very
popular that an access interface is capable of thousands of queues.
in addition, the DOCSIS has lots of QoS implementation as well, eg for
priorities... I
【在 o*********y 的大作中提到】
: Shaping is certainly used, but is it for per-user or per-group? Is it the
: same for home user or for business accounts? Will there be any interaction
: between traffic from different users?
: Except for Comcast engineers, probably seldom anyone else knows the details
: of how they enforce bandwidth. I was trying to apply some "black-box" testings, but
: obviously it cannot give me enough information. I was hoping to get some
: more precise information from people who know cable technology very well, or
: fro
term called standard. I agree each company may treak a little bit, but
basically they follow the same or similar standard.
usually it's per-user basis, not only shaping, also guaranteed bandwidth.
That's why queuing function is so important for access equipment. It's very
popular that an access interface is capable of thousands of queues.
in addition, the DOCSIS has lots of QoS implementation as well, eg for
priorities... I
【在 o*********y 的大作中提到】
: Shaping is certainly used, but is it for per-user or per-group? Is it the
: same for home user or for business accounts? Will there be any interaction
: between traffic from different users?
: Except for Comcast engineers, probably seldom anyone else knows the details
: of how they enforce bandwidth. I was trying to apply some "black-box" testings, but
: obviously it cannot give me enough information. I was hoping to get some
: more precise information from people who know cable technology very well, or
: fro
o*y
11 楼
This is very helpful.
Thanks a lot!
very
this
【在 z**r 的大作中提到】
: you don't have to be a comcast employee to get all this info, there is a
: term called standard. I agree each company may treak a little bit, but
: basically they follow the same or similar standard.
: usually it's per-user basis, not only shaping, also guaranteed bandwidth.
: That's why queuing function is so important for access equipment. It's very
: popular that an access interface is capable of thousands of queues.
: in addition, the DOCSIS has lots of QoS implementation as well, eg for
: priorities... I
Thanks a lot!
very
this
【在 z**r 的大作中提到】
: you don't have to be a comcast employee to get all this info, there is a
: term called standard. I agree each company may treak a little bit, but
: basically they follow the same or similar standard.
: usually it's per-user basis, not only shaping, also guaranteed bandwidth.
: That's why queuing function is so important for access equipment. It's very
: popular that an access interface is capable of thousands of queues.
: in addition, the DOCSIS has lots of QoS implementation as well, eg for
: priorities... I
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