[Bug 352841] Re: SCP over IPv6 address is very Slow. Takes Hours

Prasad Tadi ptadi at roshitech.com
Sat Apr 4 01:18:11 BST 2009


Bryan,

Thanks for the details....

Here is some more data following your mail.
The problem still persists...


However, when I run the command on local link (local machine's) , It  
completes and not even a single trace on tshark ip6 -i eth1

But when I traced on  " lo",  it did show the data.

cruise at CC-branch:~/newcc/projects/branch-build/dt-RelEng$ scp  
desktone.tar [fe80::250:56ff:fe8d:1ddc%eth1]:/tmp/x.tar
cruise at fe80::250:56ff:fe8d:1ddc%eth1's password:
desktone.tar                                                             
                                  100%   71MB  35.3MB/s   00:02
cruise at CC-branch:~/newcc/projects/branch-build/dt-RelEng$

# tshark ip6 -i lo
<SNIP>

  8.381329 fe80::250:56ff:fe8d:1ddc -> fe80::250:56ff:fe8d:1ddc SSHv2  
Encrypted response packet len=48
   8.381401 fe80::250:56ff:fe8d:1ddc -> fe80::250:56ff:fe8d:1ddc  
SSHv2 Encrypted request packet len=32
   8.382301 fe80::250:56ff:fe8d:1ddc -> fe80::250:56ff:fe8d:1ddc  
SSHv2 Encrypted response packet len=128
   8.383901 fe80::250:56ff:fe8d:1ddc -> fe80::250:56ff:fe8d:1ddc  
SSHv2 Encrypted request packet len=32
   8.383932 fe80::250:56ff:fe8d:1ddc -> fe80::250:56ff:fe8d:1ddc TCP  
42214 > ssh [FIN, ACK] Seq=74203897 Ack=30225 Win=39040 Len=0  
TSV=7656054 TSER=7656054
   8.419376 fe80::250:56ff:fe8d:1ddc -> fe80::250:56ff:fe8d:1ddc TCP  
ssh > 42214 [ACK] Seq=30225 Ack=74203898 Win=852224 Len=0 TSV=7656058  
TSER=7656054
   8.469483 fe80::250:56ff:fe8d:1ddc -> fe80::250:56ff:fe8d:1ddc TCP  
ssh > 42214 [FIN, ACK] Seq=30225 Ack=74203898 Win=852224 Len=0  
TSV=7656063 TSER=7656054
   8.469504 fe80::250:56ff:fe8d:1ddc -> fe80::250:56ff:fe8d:1ddc TCP  
42214 > ssh [ACK] Seq=74203898 Ack=30226 Win=39040 Len=0 TSV=7656063  
TSER=7656063

So I think though the Document suggests that it should use its own,  
the OS /APP is intelligent to route the packets through LOOP BACK (lo).


Now the data while transferring to next node.....

I tried both eth1 and eth0.

First the SCP command
ruise at CC-branch:~/newcc/projects/branch-build/dt-RelEng$ scp  
desktone.tar [fe80::250:56ff:fe8d:403c%eth0]:/tmp/x.tar
cruise at fe80::250:56ff:fe8d:403c%eth0's password:
desktone.tar                                                             
                                    2% 2112KB   2.1MB/s   00:33 ETA
desktone.tar                                                             
                                    2% 2112KB   1.7MB/s   00:41 ETA
desktone.tar                                                             
                                    2% 2112KB   1.5MB/s   00:45 ETA
desktone.tar                                                             
                                    2% 2112KB   1.2MB/s - stalled -
desktone.tar                                                             
                                    2% 2112KB   1.1MB/s - stalled -
desktone.tar                                                             
                                    3% 2208KB 918.8KB/s   01:16 ETA
desktone.tar                                                             
                                    3% 2208KB 744.2KB/s   01:34  
ETAcruise at CC-branch:~/newcc/projects/branch-build/dt-RelEng$

I killed after some time....


tshark ip6 output.... on the originator.... No Errors

<SNIP>
16.447595 fe80::250:56ff:fe8d:5c00 -> fe80::250:56ff:fe8d:403c SSHv2  
Encrypted request packet len=2856
  16.657429 fe80::250:56ff:fe8d:5c00 -> fe80::250:56ff:fe8d:403c  
SSHv2 [TCP Retransmission] Encrypted request packet len=1428
  16.657777 fe80::250:56ff:fe8d:403c -> fe80::250:56ff:fe8d:5c00 TCP  
ssh > 53692 [ACK] Seq=2209 Ack=158913 Win=64128 Len=0 TSV=78934229  
TSER=7554125
  16.657806 fe80::250:56ff:fe8d:5c00 -> fe80::250:56ff:fe8d:403c  
SSHv2 Encrypted request packet len=2856
  16.867469 fe80::250:56ff:fe8d:5c00 -> fe80::250:56ff:fe8d:403c  
SSHv2 [TCP Retransmission] Encrypted request packet len=1428
  16.867773 fe80::250:56ff:fe8d:403c -> fe80::250:56ff:fe8d:5c00 TCP  
ssh > 53692 [ACK] Seq=2209 Ack=160341 Win=64128 Len=0 TSV=78934250  
TSER=7554146
  16.867797 fe80::250:56ff:fe8d:5c00 -> fe80::250:56ff:fe8d:403c  
SSHv2 Encrypted request packet len=2856
  17.077691 fe80::250:56ff:fe8d:5c00 -> fe80::250:56ff:fe8d:403c  
SSHv2 [TCP Retransmission] Encrypted request packet len=1428
  17.078810 fe80::250:56ff:fe8d:403c -> fe80::250:56ff:fe8d:5c00 TCP  
ssh > 53692 [ACK] Seq=2209 Ack=161769 Win=64128 Len=0 TSV=78934271  
TSER=7554167
  17.078837 fe80::250:56ff:fe8d:5c00 -> fe80::250:56ff:fe8d:403c  
SSHv2 [TCP Retransmission] Encrypted request packet len=1428
  17.078843 fe80::250:56ff:fe8d:5c00 -> fe80::250:56ff:fe8d:403c  
SSHv2 [TCP Retransmission] Encrypted request packet len=1428
  17.079060 fe80::250:56ff:fe8d:403c -> fe80::250:56ff:fe8d:5c00 TCP  
ssh > 53692 [ACK] Seq=2209 Ack=163197 Win=64128 Len=0 TSV=78934271  
TSER=7554167
  17.079071 fe80::250:56ff:fe8d:5c00 -> fe80::250:56ff:fe8d:403c  
SSHv2 [TCP Retransmission] Encrypted request packet len=1428
  17.079075 fe80::250:56ff:fe8d:403c -> fe80::250:56ff:fe8d:5c00 TCP  
ssh > 53692 [ACK] Seq=2209 Ack=164625 Win=62720 Len=0 TSV=78934271  
TSER=7554167
  17.079086 fe80::250:56ff:fe8d:5c00 -> fe80::250:56ff:fe8d:403c  
SSHv2 [TCP Retransmission] Encrypted request packet len=1428
  17.079330 fe80::250:56ff:fe8d:403c -> fe80::250:56ff:fe8d:5c00 TCP  
ssh > 53692 [ACK] Seq=2209 Ack=166053 Win=64128 Len=0 TSV=78934271  
TSER=7554167
  17.079340 fe80::250:56ff:fe8d:5c00 -> fe80::250:56ff:fe8d:403c  
SSHv2 [TCP Retransmission] Encrypted request packet len=1428
  17.079345 fe80::250:56ff:fe8d:403c -> fe80::250:56ff:fe8d:5c00 TCP  
ssh > 53692 [ACK] Seq=2209 Ack=167481 Win=62720 Len=0 TSV=78934271  
TSER=7554167
  17.079353 fe80::250:56ff:fe8d:5c00 -> fe80::250:56ff:fe8d:403c  
SSHv2 [TCP Retransmission] Encrypted request packet len=1428
  17.079566 fe80::250:56ff:fe8d:403c -> fe80::250:56ff:fe8d:5c00 TCP  
ssh > 53692 [ACK] Seq=2209 Ack=170337 Win=62720 Len=0 TSV=78934271  
TSER=7554167
  17.079572 fe80::250:56ff:fe8d:5c00 -> fe80::250:56ff:fe8d:403c  
SSHv2 [TCP Retransmission] Encrypted request packet len=1428
  17.079577 fe80::250:56ff:fe8d:5c00 -> fe80::250:56ff:fe8d:403c  
SSHv2 [TCP Retransmission] Encrypted request packet len=1428
  17.079581 fe80::250:56ff:fe8d:5c00 -> fe80::250:56ff:fe8d:403c  
SSHv2 [TCP Retransmission] Encrypted request packet len=1428
  17.079788 fe80::250:56ff:fe8d:403c -> fe80::250:56ff:fe8d:5c00 TCP  
ssh > 53692 [ACK] Seq=2209 Ack=173193 Win=62720 Len=0 TSV=78934271  
TSER=7554167
  17.111825 fe80::250:56ff:fe8d:403c -> fe80::250:56ff:fe8d:5c00 TCP  
ssh > 53692 [ACK] Seq=2209 Ack=174621 Win=64128 Len=0 TSV=78934275  
TSER=7554167
  17.111849 fe80::250:56ff:fe8d:5c00 -> fe80::250:56ff:fe8d:403c  
SSHv2 [TCP Retransmission] Encrypted request packet len=1428
  17.151649 fe80::250:56ff:fe8d:403c -> fe80::250:56ff:fe8d:5c00 TCP  
ssh > 53692 [ACK] Seq=2209 Ack=176049 Win=64128 Len=0 TSV=78934279  
TSER=7554170
  17.151673 fe80::250:56ff:fe8d:5c00 -> fe80::250:56ff:fe8d:403c  
SSHv2 [TCP Retransmission] Encrypted request packet len=1428
  17.155241 fe80::250:56ff:fe8d:403c -> fe80::250:56ff:fe8d:5c00 TCP  
ssh > 53692 [ACK] Seq=2209 Ack=177478 Win=64128 Len=0 TSV=78934279  
TSER=7554174
  17.155521 fe80::250:56ff:fe8d:403c -> fe80::250:56ff:fe8d:5c00 TCP  
ssh > 53692 [FIN, ACK] Seq=2209 Ack=177478 Win=64128 Len=0  
TSV=78934279 TSER=7554174
  17.155534 fe80::250:56ff:fe8d:5c00 -> fe80::250:56ff:fe8d:403c TCP  
53692 > ssh [ACK] Seq=177478 Ack=2210 Win=10496 Len=0 TSV=7554174  
TSER=78934279
335 packets captured
root at CC-branch:~#

Thanks
Prasad


On Apr 3, 2009, at 4:53 PM, Bryan McLellan wrote:

> On Fri, Apr 3, 2009 at 12:23 PM, Prasad Tadi <ptadi at roshitech.com>  
> wrote:
>> I am not really an expert, but I think the "Local link" may use  
>> Loop back
>>
>> Link-local is the fe80 addresses that refer to devices on a  
>> particular data link, such as a single Ethernet network, or a  
>> point-to-point serial connection.  If you're using your own link- 
>> local address, then yes, that traffic will - I believe - traverse  
>> the loopback interface.
>
> This is not correct. If you read the link I provided earlier it starts
> with "All interfaces have an associated link-local address". Loopback
> is it's own interface (lo) and is independent of your ethN interfaces.
> The loopback interface also has it's own inet6 address (ifconfig lo0 |
> grep inet6) in the specified ipv6 loopback address range.
>
>> eth1      Link encap:Ethernet  HWaddr 00:50:56:b5:52:c1
>>          inet6 addr: fdf8:c879:493e:1:250:56ff:feb5:52c1/64  
>> Scope:Global
>>          inet6 addr: fe80::250:56ff:feb5:52c1/64 Scope:Link
>
> The second address, that starts with fe80::, and additionally says
> "Scope: Link" is the "Link Local" address. This is because this
> address is for the local link only.
>
> Try copying between two hosts using these address with Scope:Link to
> rule out any addressing problems. Because these are local addresses,
> you may need to specify the interface you want scp to use by adding
> '%interface' to the end of the address, such as:
>
> scp -6 desktone.tar [fdf8:c879:493e:1:250:56ff:feb5:52c1%eth1]:/tmp
>
> It may be helpful to run 'sudo tshark ip6' on the originating host
> while copying the file to look for any network errors.
>
> -- 
> SCP over IPv6 address is very Slow. Takes Hours
> https://bugs.launchpad.net/bugs/352841
> You received this bug notification because you are a direct subscriber
> of the bug.
>
> Status in “openssh” source package in Ubuntu: New
>
> Bug description:
> Binary package hint: openssh-server
>
> Hi,
>
> I am using Ubutu Hardy release 8.04 and openssh 4.7P1
>
>
> lsb_release -a
> No LSB modules are available.
> Distributor ID: Ubuntu
> Description:    Ubuntu 8.04.1
> Release:        8.04
> Codename:       hardy
> root at htaf1:~#
> OpenSSH_4.7p1 Debian-8ubuntu1.2, OpenSSL 0.9.8g 19 Oct 2007
>
>
> When I copy a 50+ MB file from one system to another  Ubuntu
>
> Using IPv4 address  it took just less than 3 sec.
> Same thing over IPv6 took more than an hour ( 1 Hr and 20 Min)
>
> I copied the file using local IPv6 address. It ran fine. May be it  
> is using loop back, instead of real IPv6 address
>
>
> When I initiate the same from a free BSD box to BSD It took less  
> than 3 sec on both Ipv4 and IPv6.
> I can also copy from Ubuntu to a FreeBSD box faster both Ipv4 and  
> IPv6 addreses.
>
> I just can't copy the same from a Ubutu to Ubutu or other machines  
> to Ubuntu over IPv6 address.
>
> It is very critical for our product :-(
>
> I even tried getting the latest OpenSSH package from openssh.org  
> and compiled that module and ran that sshd.
> Still no use. Same old behaviour.
>
> It starts negotiating at 1.5 Mb/ sec and slowly drops to few KB /  
> sec and stalls the copy process during the time.
>
> Any updates or known issues.
>
> thanks in advance for your information on this issue.

====== Together we can build a better process =======
Prasad Tadi
ptadi at roshitech.com
http://www.roshitech.com
Fax: (270) 568-6295
cell: 603-809-7186

-- 
SCP over IPv6 address is very Slow. Takes Hours
https://bugs.launchpad.net/bugs/352841
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