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178 posts

Master Geek
+1 received by user: 11


  Reply # 520537 13-Sep-2011 16:24 Send private message

I raised a ticket with their help desk last night.

After convincing them that it had nothing to do with my modem (since it affects at least one other customer of theirs, and my modem delivers full speed anyway),
And ruling out the foreign server as the problem before they even tried that one on (since other people get faster speeds on a single connection no problem),
And, of course, telling them I was talking about my download speed, not the upload speed, all relayed from me to 2nd level support via the 1st level dude because the 2nd level support staff "don't talk to customers" because "they just don't", in spite of the fact that it would be quicker, and less would be lost in the translation.

They wanted a traceroute. So I've sent one. So far, I've got the bog standard "do you want help setting up your PS3", etc email, and one largely canned response saying they'll look into the issue, and will get back to me "after further investigation".


Just for kicks, if you send their help desk automaton a tracepath and a traceroute, here is what it suggests:
Title: User Guide - Featurelink
Title: How to setup Playstation 2
Title: Set up a new Paradise dial up connection under Macintosh OS 8
Title: Setting Up PS3 with Broadband
Title: How to set up Nintendo Wii connection

566 posts

Ultimate Geek
+1 received by user: 2

Trusted
TelstraClear

  Reply # 520807 14-Sep-2011 10:02 Send private message

Hi jnawk,

TelstraClear does not apply rate shaping for any reason other than the plan speed. In other words, if the customer has a 15Mbps plan, they are rate shaped to 15Mbps. There is no other shaping applied.

If you PM me the traceroute and your account number one of the IS architecture team will have a look at this. They've also asked for details of your OS (including version) and anything else that might help them replicate the issue.

Thanks, Gary

Have plan, send $NZD50m
3475 posts

Uber Geek
+1 received by user: 75

Subscriber

  Reply # 520821 14-Sep-2011 10:20 Send private message

This is a really interesting thread but I'm a bit confused.

People keep talking early on about how tcp won't do more than 3.5mbit over that distance yet the OP claims his friend is managing it. How can this be so?

Also I ran a traceroute to the domain myself and see it's got 5 hops outside of Telstra's control. OP do you have a traceroute from your XNet friend to compare?





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178 posts

Master Geek
+1 received by user: 11


  Reply # 520889 14-Sep-2011 11:56 Send private message

TelstraClear: Hi jnawk,

TelstraClear does not apply rate shaping for any reason other than the plan speed. In other words, if the customer has a 15Mbps plan, they are rate shaped to 15Mbps. There is no other shaping applied.

If you PM me the traceroute and your account number one of the IS architecture team will have a look at this. They've also asked for details of your OS (including version) and anything else that might help them replicate the issue.

Thanks, Gary


I can't figure out how to PM you, but I already have a ticket with the traceroute attached.

T5599736 [Incident:110912-000430]

Operating system: openSUSE 11.4 (same as friend on XNet). 

As I told the helpdesk (and the world via this thread) - I can get 15mbit/sec if and only if I spawn multiple TCP sessions - each appears limited to 3-4mbit/sec.  And I'm not your only customer experiencing the same scenario, hence ruling out my cable modem.  (Your other customer lives very near to me, so perhaps we share a common piece of hardware on your network?)

As mentioned here - the friend on XNet has not done any TCP tuning (I have, with no significant results - as detailed here in this thread).  Significantly, his Receive window remains at the default size of 128k. His latency is 150msec, mine is 159msec.

Time of day is not a factor, as he can get his approx. 10mbit/sec down a single connection at the same time of day as I get only 3-4mbit/sec.  Interestingly, my connection takes about 10mbytes of actual data transferred before achieving my peak speed, as does his - just the peak speed differs, and obviously, the wall clock time required to reach it.

If it will help, I have got a traceroute and tracepath from the XNet connection.  I know others here are interested.

x.x.x.y and x.x.x.z are his PC's RFC1918 iP address and his DSL Router's RFC1918 IP address.  Masking them is a manifestation of my tin-hat.

:~ # traceroute -n 173.231.39.84                                     
traceroute to 173.231.39.84 (173.231.39.84), 30 hops max, 40 byte packets using
UDP                                                                             
 1  x.x.x.z (x.x.x.z)  0.953 ms   0.776 ms   0.924 ms                         
 2  182.154.0.21 (182.154.0.21)  22.525 ms   27.424 ms   26.640 ms              
 3  114.31.203.90 (114.31.203.90)  26.131 ms   25.503 ms   24.773 ms            
 4  114.31.203.89 (114.31.203.89)  24.108 ms   27.006 ms   26.315 ms            
 5  114.31.202.43 (114.31.202.43)  146.035 ms   150.346 ms   149.580 ms         
 6  114.31.202.88 (114.31.202.88)  22.888 ms   25.636 ms   24.895 ms            
 7  114.31.199.112 (114.31.199.112)  147.764 ms   148.956 ms   148.189 ms       
 8  206.223.143.2 (206.223.143.2)  158.043 ms   172.288 ms   172.363 ms         
 9  67.199.135.234 (67.199.135.234)  157.868 ms   163.778 ms   156.493 ms       
10  173.231.0.18 (173.231.0.18)  159.795 ms   159.005 ms   159.269 ms           
11  173.231.0.26 (173.231.0.26)  155.299 ms   157.740 ms   157.024 ms           
12  173.231.39.84 (173.231.39.84)  156.750 ms   161.530 ms   160.726 ms

:~ # tracepath -n 173.231.39.84                                      
 1:  x.x.x.y                                              0.329ms pmtu 1500    
 1:  x.x.x.z                                              1.186ms              
 1:  x.x.x.z                                              1.147ms              
 2:  x.x.x.z                                              1.245ms pmtu 1492    
 2:  182.154.0.21                                         36.198ms asymm  3     
 3:  no reply                                                                   
 4:  114.31.203.89                                        32.495ms              
 5:  114.31.202.43                                       157.412ms asymm  9     
 6:  114.31.202.88                                        33.497ms              
 7:  114.31.199.112                                      158.438ms              
 8:  206.223.143.2                                       175.493ms              
 9:  67.199.135.234                                      166.472ms asymm  8     
10:  173.231.0.18                                        165.929ms asymm  9     
11:  173.231.0.26                                        165.996ms asymm 10     
12:  173.231.39.84                                       166.854ms reached      
     Resume: pmtu 1492 hops 12 back 54       



And for those here who aren't privy to the Telstra Clear help desk, here are my own tracepaths and traceroutes, again, my IP address is masked as a manifestation of my tin-hat.

:~ # tracepath -n 173.231.39.84
1: x.x.x.y 7.472ms pmtu 1500
1: no reply
2: 218.101.61.124 147.643ms asymm 3
3: no reply
4: 203.98.50.1 20.710ms asymm 3
5: 203.98.50.251 21.490ms asymm 4
6: 203.167.233.10 20.247ms asymm 5
7: 202.84.142.106 147.580ms asymm 6
8: 202.84.251.238 147.281ms asymm 7
9: 206.223.143.122 152.605ms asymm 8
10: 216.218.213.250 155.251ms asymm 13
11: 173.231.0.66 168.804ms asymm 13
12: 173.231.0.26 153.828ms asymm 13
13: 173.231.39.84 157.154ms reached
Resume: pmtu 1500 hops 13 back 51


:~ # traceroute -n 173.231.39.84
traceroute to 173.231.39.84 (173.231.39.84), 30 hops max, 60 byte packets
1 * * *
2 218.101.61.124 12.107 ms 11.132 ms 10.302 ms
3 * * *
4 203.98.50.1 19.537 ms 30.764 ms 31.401 ms
5 203.98.50.251 30.740 ms 29.749 ms 27.694 ms
6 203.167.233.10 27.034 ms 25.384 ms 24.627 ms
7 202.84.142.106 147.513 ms 167.227 ms 155.329 ms
8 202.84.251.238 147.304 ms 147.167 ms 147.147 ms
9 206.223.143.122 146.602 ms 167.755 ms 167.189 ms
10 216.218.213.250 166.767 ms 156.473 ms 153.321 ms
11 173.231.0.66 158.721 ms 158.834 ms 158.221 ms
12 173.231.0.26 154.582 ms 154.239 ms 153.485 ms
13 173.231.39.84 156.271 ms 155.593 ms 153.991 ms





Have plan, send $NZD50m
3475 posts

Uber Geek
+1 received by user: 75

Subscriber

  Reply # 520903 14-Sep-2011 12:06 Send private message

Resume: pmtu 1492 hops 12 back 54
Resume: pmtu 1500 hops 13 back 51

So the return path is different?

Also the mtu is different in both systems?  So are you getting packet fragmentation somewhere?

also can we have the trace without the -n option.  It's hard to compare.







Promote New Zealand - Get yourself a .kiwi.nz domain name!!!

Check out mine - i.am.a.can.do.kiwi.nz - [email protected]


601 posts

Ultimate Geek
+1 received by user: 5

Trusted

  Reply # 520949 14-Sep-2011 13:27 Send private message

DonGould: This is a really interesting thread but I'm a bit confused.

People keep talking early on about how tcp won't do more than 3.5mbit over that distance yet the OP claims his friend is managing it. How can this be so?

Also I ran a traceroute to the domain myself and see it's got 5 hops outside of Telstra's control. OP do you have a traceroute from your XNet friend to compare?



I'm probably completely confused here, but I'll try.

Well, the base rate is under the control of the TCP receive window size, since the sender will only send enough data to fill the window, and will then stop and wait for an ACK.

The traffic on the TCP connection ends up looking like:

Burst...WaitForAck...Burst...WaitForAck...

The length of time for the WaitForACK is the length of time for the last packet in the burst to get to the receiver and the ACK to return, the Round Trip Time (RTT).

So, we end up with an equation where the maximum throughput of a connection is dominated by the silence while you wait for an ACK:

throughput <= RWIN/RTT

Where:
RWIN is the receive window size
RTT is the round trip time.

in regular TCP, RWIN has a maximum value of 65536, so that means that given a RTT of 150ms, we have a throughput of:

(65536 Bytes/0.150s  = 3,495,253.33 bits/s = 3.5mbps. 

http://en.wikipedia.org/wiki/TCP_tuning 

However, the TCP guys got together and said, "Hey, we're sending this thing over long fat links (satellite) and we can't use the entire bandwidth.  That sucks for transferring large files.  I paid for 15mbps, I want my 15!"  So they added an extension to TCP, allowing a scaling factor to be added to the RWIN.  If both sides report a scaling factor, then the system will allow larger RWINs, resulting in the throughput no longer being dominated by the RTT.

http://en.wikipedia.org/wiki/TCP_window_scale_option








178 posts

Master Geek
+1 received by user: 11


  Reply # 520965 14-Sep-2011 14:04 Send private message

DonGould: The mtu is different in both systems?  So are you getting packet fragmentation somewhere?


Any fragmentation happening would happen on the other guy's connection since his is the connection where the pMTU drops.  For my connection it remains at 1500 the whole way.



178 posts

Master Geek
+1 received by user: 11


  Reply # 520970 14-Sep-2011 14:11 Send private message

jpollock:I'm probably completely confused here, but I'll try.
...


Yup, that is where I was at with this on Monday.  I spent a great deal more time on it than perhaps I should.

Earlier, it was suggested that as a cheap and dirty way of shaping an individual TCP session, TC might have been stripping out the TCP option required for a window of more than 64k.  But a TCPdump disproved that.

I've played around with increasing the RWIN - had it as high as 512kBytes - in theory big enough for around 27mbit/sec.  And I've also got control of the other end, and had cranked its corresponding transmit window (ie, the largest it would actually be prepared to make it) up to the same size.  All with zero effect.  And all moot anyway, since the other guy gets 10mbit/sec with the default 128k RWIN.

Perhaps I'll give reducing the MTU a little a go.  Perhaps a router along the way isn't playing nice with tracepath.
 



178 posts

Master Geek
+1 received by user: 11


  Reply # 520974 14-Sep-2011 14:24 Send private message

jnawk: Perhaps I'll give reducing the MTU a little a go.  Perhaps a router along the way isn't playing nice with tracepath.
 


Dropped it to 1492, no change. Dropped it to 1480, no change.  Dropped it to 1460, no change.

Dropped it to 1000, lost my SSH session to the box, had to go one box back, drop its internal NIC's MTU to 1000, so I could SSH in again to increase the MTU back to 1500.

Summary:  MTU made no difference.  Without another TCPdump during a transfer to look for fragments (not doing that remotely!), No change.


566 posts

Ultimate Geek
+1 received by user: 2

Trusted
TelstraClear

  Reply # 521351 15-Sep-2011 10:23 Send private message

Hi jnawk,

One of our tecnical team would like to contact you about this. If you email me at [email protected] I'll pass your contact to him.

Cheers, Gary



178 posts

Master Geek
+1 received by user: 11


  Reply # 521713 15-Sep-2011 22:24 Send private message

TelstraClear: Hi jnawk,

One of our tecnical team would like to contact you about this. If you email me at?[email protected] I'll pass your contact to him.

Cheers, Gary


For the record, Gary has kept his word, and I've been exchanging emails with someone who appears to know a great deal. I'll post my results after that person has had a chance to review my findings thus far. Suffice to say, the ball is in TC's court at present.



178 posts

Master Geek
+1 received by user: 11


  Reply # 521958 16-Sep-2011 14:09 Send private message

jnawk: For the record, Gary has kept his word, and I've been exchanging emails with someone who appears to know a great deal. I'll post my results after that person has had a chance to review my findings thus far. Suffice to say, the ball is in TC's court at present.


Gary has advised the matter has been escalated to "Complex faults".

601 posts

Ultimate Geek
+1 received by user: 5

Trusted

  Reply # 523711 20-Sep-2011 19:46 Send private message

jnawk:
jnawk: For the record, Gary has kept his word, and I've been exchanging emails with someone who appears to know a great deal. I'll post my results after that person has had a chance to review my findings thus far. Suffice to say, the ball is in TC's court at present.


Gary has advised the matter has been escalated to "Complex faults".


Any updates? 






178 posts

Master Geek
+1 received by user: 11


  Reply # 523731 20-Sep-2011 20:16 Send private message

jpollock: Any updates??


Watch this space - Garry asked for me to give them until Friday. You'll know the outcome here first.

566 posts

Ultimate Geek
+1 received by user: 2

Trusted
TelstraClear

  Reply # 523892 21-Sep-2011 09:23 Send private message

jnawk:
jpollock: Any updates??


Watch this space - Garry asked for me to give them until Friday. You'll know the outcome here first.


Hi Jnawk, one one of the team has trying to contact you - can you PM me with the best phone number?

Cheers, Gary

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