[c-nsp] Performance issue on link

[Tony]

That doesn't sound at all good. No way should you need that many (25) sessions.

Is there any other traffic on the link ? Is it brand new ? Any duplex mismatch type issues ?

I would suggest running an "iperf -u -d" to run UDP in both directions at the same time, might turn up something unusual. Remove any other devices (ie. your routers) before testing so you will know that is not a problem. I assume your two linux test machines are on the same L3 subnet from what you've described ?


regards,
Tony.







>________________________________
> From: CiscoNSP List <cisconsp_list at hotmail.com>
>To: "td_miles at yahoo.com" <td_miles at yahoo.com>; Azher Mughal <azher at hep.caltech.edu> 
>Cc: "cisco-nsp at puck.nether.net" <cisco-nsp at puck.nether.net> 
>Sent: Tuesday, 2 April 2013 10:37 AM
>Subject: RE: [c-nsp] Performance issue on link
> 
>
> 
>Sorry - Forgot to add:
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>POP A -> POP B - only requires 8 sessions, but POP B -> POP A requires 25 sessions to achieve ~38Mb?
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>> From: cisconsp_list at hotmail.com
>> To: td_miles at yahoo.com; azher at hep.caltech.edu
>> Date: Tue, 2 Apr 2013 11:28:50 +1100
>> CC: cisco-nsp at puck.nether.net
>> Subject: Re: [c-nsp] Performance issue on link
>> 
>> Thanks Tony - With multiple sessions (8), I can achieve ~38Mb/sec consistently.
>> 
>> Is it simply not feasible to expect ~40Mb with a single tcp transfer (Without significant adjustments to both Linux servers?)
>> 
>> 
>> > Date: Mon, 1 Apr 2013 17:10:42 -0700
>> > From: td_miles at yahoo.com
>> > Subject: Re: [c-nsp] Performance issue on link
>> > To: cisconsp_list at hotmail.com; azher at hep.caltech.edu
>> > CC: cisco-nsp at puck.nether.net
>> > 
>> > Try using multiple TCP sessions  "iperf -P 5"  (note - capital "P").
>> > 
>> > 
>> > regards,
>> > Tony.
>> > 
>> > 
>> > 
>> > 
>> > 
>> > ----- Original Message -----
>> > > From: CiscoNSP List <cisconsp_list at hotmail.com>
>> > > To: Azher Mughal <azher at hep.caltech.edu>
>> > > Cc: "cisco-nsp at puck.nether.net" <cisco-nsp at puck.nether.net>
>> > > Sent: Tuesday, 2 April 2013 9:51 AM
>> > > Subject: Re: [c-nsp] Performance issue on link
>> > > 
>> > >T hanks - Ill check them out now
>> > > 
>> > >>  Date: Mon, 1 Apr 2013 16:16:36 -0700
>> > >>  From: azher at hep.caltech.edu
>> > >>  To: cisconsp_list at hotmail.com
>> > >>  CC: cisco-nsp at puck.nether.net
>> > >>  Subject: Re: [c-nsp] Performance issue on link
>> > >> 
>> > >>  These might be helpful:
>> > >> 
>> > >>  http://fasterdata.es.net/network-tuning/
>> > >> 
>> > >> 
>> > > http://www.mellanox.com/related-docs/prod_software/Performance_Tuning_Guide_for_Mellanox_Network_Adapters.pdf
>> > >> 
>> > >>  -Azher
>> > >> 
>> > >>  On 4/1/2013 3:51 PM, CiscoNSP List wrote:
>> > >>  > Hi,
>> > >>  >
>> > >>  > We have a 40Mb link between 2 POPs - Latency ~65m/sec (No packet-loss)
>> > >>  >
>> > >>  > POP A Is a 7301 and 2960POP B is a 7200 and 4948
>> > >>  >
>> > >>  > 40Mb link is connected to the two switches (L2), and then a trunk link 
>> > > to both routers for all L3.
>> > >>  >
>> > >>  > Have a Linux server connected to both switches, and achieve the 
>> > > following performance:
>> > >>  >
>> > >>  > IPERF (UDP)
>> > >>  > POP A -> POP B - 38.5Mb/secPOP B -> POP A - 38.5Mb/sec
>> > >>  >
>> > >>  > IPERF (TCP)
>> > >>  > POP A -> POP B - ~20Mb/secPOP B -> POP A - ~12Mb/sec
>> > >>  >
>> > >>  > FTP
>> > >>  > POP A -> POP B - ~38Mb/secPOP B -> POP A - ~16Mb/sec
>> > >>  >
>> > >>  > WGET
>> > >>  > POP A -> POP B - ~30Mb/sec POP B -> POP A - ~16Mb/sec
>> > >>  >
>> > >>  > Any suggestions on why I am seeing poor performance with TCP 
>> > > transfers? (Especially POP B -> POP A direction) - I've tried adjusting 
>> > > the window size in IPERF but it actually made the results worse?
>> > >>  > Thanks in advance.
>> > >>  >
>> 
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