[Freeswitch-users] Problem with rtp streams and stair-stepped (or ramped) increased lag

Nathan Neulinger nneul at mst.edu
Thu Jun 27 18:36:08 MSD 2013


I think I gave it either 2 or 4 cores... On the test instance, most likely 1 or 2 calls including the test one. It's not 
a loading issue as near as I can tell - at least not the slow stairstep one.

-- Nathan

On 06/27/2013 09:24 AM, William King wrote:
> How many cores did your VM have assigned to it? And how many concurrent
> calls did you have up at the time?
>
> William King
> Senior Engineer
> Quentus Technologies, INC
> 1037 NE 65th St Suite 273
> Seattle, WA 98115
> Main:   (877) 211-9337
> Office: (206) 388-4772
> Cell:   (253) 686-5518
> william.king at quentustech.com
>
> On 06/26/2013 11:47 AM, Nathan Neulinger wrote:
>> Do the same caveats apply to voipmonitor? The graphs from voipmonitor are showing very clear stair stepping.
>>
>> This most recent test was 100% SIP, no skinny involved.
>>
>> At the moment, I'm waiting for any additional reports of the "bad" calls - i.e. the one that jumps to 2000+ ms. I
>> haven't seen any of those yet on the real hardware, only the slow climb case.
>>
>> These are the two graphs on voipmonitor for the test call between two phones on my desk left sitting there for 40 minutes:
>>
>> http://i.imgur.com/3kx5q8z.png
>>
>> http://i.imgur.com/pj2cMN7.png
>>
>> -- Nathan
>>
>> On 06/26/2013 12:08 PM, Anthony Minessale wrote:
>>> While a useful tool, You can't 100% rely on wireshark to report delay, it fails to properly deal with things such as
>>> mark bits clearing the buffer etc and you have to trust it's clock to be accurate too.
>>>
>>> You should back it up with audio tests, call yourself and talk into it and measure for latency as well, also looking at
>>> pcap of both ends of the call using the inbound ts vs the outbound.
>>>
>>> Another control you should use is to try sip 2 sip.  It's possible that the skinny is lacking some of the RTP flags that
>>> other channels use that help reduce latency.
>>>
>>>
>>>
>>>
>>> On Wed, Jun 26, 2013 at 11:09 AM, Nathan Neulinger <nneul at mst.edu <mailto:nneul at mst.edu>> wrote:
>>>
>>>      Got everything moved to real hardware... still seeing an issue with stair stepping.
>>>
>>>      Hardware is a Dell 1950 with dual dual or dual quad xeons.
>>>
>>>      I've got the debug level turned up on the boxes again and am capturing a call.
>>>
>>>      The test case where I saw the stair stepping was:
>>>
>>>      PolyCom 550 -> FS -> PolyCom 350
>>>      All local network w/ < 1ms typically.
>>>
>>>      Just connected from one to the other and left them connected for a half hour. Over the call, delay drift increased to 80
>>>      ms it looked like. Now, that's not one of the problem calls, still waiting to see if I see any of those while running on
>>>      real hardware.
>>>
>>>      This test case is on master from within past few days.
>>>
>>>      -- Nathan
>>>
>>>      On 06/25/2013 07:55 PM, William King wrote:
>>>       > You mentioned you were using VMWare to run FS in a virtual setup. What's
>>>       > the OS and the physical NIC on the host box?
>>>       >
>>>       > I'm using Linux kernel 3.2 with RTL8111/8168B chipset for the NIC.
>>>       >
>>>       > William King
>>>       > Senior Engineer
>>>       > Quentus Technologies, INC
>>>       > 1037 NE 65th St Suite 273
>>>       > Seattle, WA 98115
>>>       > Main:   (877) 211-9337
>>>       > Office: (206) 388-4772
>>>       > Cell:   (253) 686-5518
>>>       > william.king at quentustech.com <mailto:william.king at quentustech.com>
>>>       >
>>>       > On 06/25/2013 05:36 PM, Nathan Neulinger wrote:
>>>       >> Both... Graphs are from voipmonitor, but the wide shifts in delay are
>>>       >> very visible when processing the stream in wireshark.
>>>       >>
>>>       >> -- Nathan
>>>       >>
>>>       >> On 06/25/2013 07:35 PM, William King wrote:
>>>       >>> What are you using to analyze the rtp streams? Wireshark? or voipmonitor?
>>>       >>>
>>>       >>> William King
>>>       >>> Senior Engineer
>>>       >>> Quentus Technologies, INC
>>>       >>> 1037 NE 65th St Suite 273
>>>       >>> Seattle, WA 98115
>>>       >>> Main:   (877) 211-9337
>>>       >>> Office: (206) 388-4772
>>>       >>> Cell:   (253) 686-5518
>>>       >>> william.king at quentustech.com <mailto:william.king at quentustech.com>
>>>       >>>
>>>       >>> On 06/25/2013 05:19 PM, Nathan Neulinger wrote:
>>>       >>>> Very interesting... look forward to seeing the comparison of those two
>>>       >>>> captures... I'm in the process of trying to rule out vmware as a
>>>       >>>> contributing factor by moving the FS servers to dedicated hardware, but
>>>       >>>> your description sounds like there may be some other issue in addition.
>>>       >>>>
>>>       >>>> In my case, it's all confined within local network, so there shouldn't
>>>       >>>> be much of any latency spikes, at least not significant ones.
>>>       >>>>
>>>       >>>> Looking at the graphs of a few calls today, on at least one of the
>>>       >>>> not-so-bad ones, I saw a very periodic blip on the stairstep every 60
>>>       >>>> seconds. That doesn't cover the large drift ones in the graphs I posted
>>>       >>>> though.
>>>       >>>>
>>>       >>>> -- Nathan
>>>       >>>>
>>>       >>>> On 06/25/2013 06:48 PM, William King wrote:
>>>       >>>>> Nathan,
>>>       >>>>>
>>>       >>>>> I had a chance to diagnose the issue live on a system today. While I'm
>>>       >>>>> not yet sure we are hitting the same issue, I'm now confident the
>>>       >>>>> problem I'm hitting is not FS related, but looks to be kernel
>>>       >>>>> related. I
>>>       >>>>> was able to get multiple calls up all with large 5+ second delays.
>>>       >>>>> Restarting the calls did nothing to clear the problem. Restarting
>>>       >>>>> Freeswitch repeatedly also had no effect. Upon restarting the box, the
>>>       >>>>> problem was gone.
>>>       >>>>>
>>>       >>>>> Also in my diagnostics I've found that it isn't all UDP packets that
>>>       >>>>> are
>>>       >>>>> effected. I now have a switch mirroring the port and a pcap running
>>>       >>>>> locally on the machine. I'll see tomorrow if it's just a matter of an
>>>       >>>>> inbound or outbound network stack buffer(or network stack priority)
>>>       >>>>> issue.
>>>       >>>>>
>>>       >>>>> William King
>>>       >>>>> Senior Engineer
>>>       >>>>> Quentus Technologies, INC
>>>       >>>>> 1037 NE 65th St Suite 273
>>>       >>>>> Seattle, WA 98115
>>>       >>>>> Main:   (877) 211-9337
>>>       >>>>> Office: (206) 388-4772
>>>       >>>>> Cell:   (253) 686-5518
>>>       >>>>> william.king at quentustech.com <mailto:william.king at quentustech.com>
>>>       >>>>>
>>>       >>>>> On 06/25/2013 05:13 AM, Nathan Neulinger wrote:
>>>       >>>>>> I guess the big question is this:
>>>       >>>>>>
>>>       >>>>>>       Is it _supposed_ to recover?
>>>       >>>>>>
>>>       >>>>>>     From Tony's notes, it's sounding like it's very critically
>>>       >>>>>> dependent on the timer in the switch, which very well be the
>>>       >>>>>> current cause of my issues.
>>>       >>>>>>
>>>       >>>>>> What I probably need to do is have a pair of phones automatically
>>>       >>>>>> calling each other, and just leaving them up - just to
>>>       >>>>>> generate a continuous independent background stream. That'll tell me
>>>       >>>>>> if any glitches are specific to a particular
>>>       >>>>>> channel, or if they are common across multiple calls - which I'd
>>>       >>>>>> expect if the timer was swinging.
>>>       >>>>>>
>>>       >>>>>> I don't know where my latency is being introduced unfortunately...
>>>       >>>>>>
>>>       >>>>>> -- Nathan
>>>       >>>>>>
>>>       >>>>>> On 06/25/2013 01:59 AM, Avi Marcus wrote:
>>>       >>>>>>> It sounds like I saw  this on a home internet connection to a public
>>>       >>>>>>> server when the connection had varying latency.
>>>       >>>>>>> Once the call jittered, it never recovered.
>>>       >>>>>>> My stop-gap was to add a small jitter buffer
>>>       >>>>>>> <http://wiki.freeswitch.org/wiki/Jitterbuffer>, e.g. <action
>>>       >>>>>>> application="jitterbuffer" data="100:200:20"/> to the user dialplan.
>>>       >>>>>>> This /seemed /to make FS handle rewriting the timestamps for drift
>>>       >>>>>>> rather than relying on the Linksys ATA to do that.
>>>       >>>>>>>
>>>       >>>>>>> Probably the wrong solution, but all I had time/understanding for.
>>>       >>>>>>> -Avi
>>>       >>>>>>>
>>>       >>>>>>>
>>>       >>>>>>> On Tue, Jun 25, 2013 at 4:42 AM, Nathan Neulinger <nneul at mst.edu <mailto:nneul at mst.edu>
>>>       >>>>>>> <mailto:nneul at mst.edu <mailto:nneul at mst.edu>>> wrote:
>>>       >>>>>>>
>>>       >>>>>>>
>>>       >>>>>>>
>>>       >>>>>>>        On 06/24/2013 08:24 PM, Anthony Minessale wrote:
>>>       >>>>>>>         > fsctl debug_level 10
>>>       >>>>>>>         > Also make sure ve host has high res timing.
>>>       >>>>>>>
>>>       >>>>>>>        Turned up logging, will wait for next occurrence.
>>>       >>>>>>>
>>>       >>>>>>>        Not sure on the latter - it's a vmware ESXi 5.1 box running FC
>>>       >>>>>>> 17 x86_64 as the guest.
>>>       >>>>>>>
>>>       >>>>>>>        /dev/rtc /dev/rtc0 exist
>>>       >>>>>>>        posix and soft timers are loaded in fs
>>>       >>>>>>>
>>>       >>>>>>>        I've got a bunch of unused Dell 1950's on hand, so could use a
>>>       >>>>>>> few of those machines if needed to get vmware out of the
>>>       >>>>>>>        picture.
>>>       >>>>>>>
>>>       >>>>>>>        -- Nathan
>>>       >>>>>>>
>>>       >>>>>>>        ------------------------------------------------------------
>>>       >>>>>>>        Nathan Neulinger nneul at mst.edu <mailto:nneul at mst.edu> <mailto:nneul at mst.edu <mailto:nneul at mst.edu>>
>>>       >>>>>>>        Missouri S&T Information Technology (573) 612-1412
>>>       >>>>>>> <tel:%28573%29%20612-1412>
>>>       >>>>>>>        System Administrator - Architect
>>>       >>>>>>>
>>>       >>>>>>>
>>>       >>>>>>> _________________________________________________________________________
>>>       >>>>>>>
>>>       >>>>>>>
>>>       >>>>>>>        Professional FreeSWITCH Consulting Services:
>>>       >>>>>>> consulting at freeswitch.org <mailto:consulting at freeswitch.org> <mailto:consulting at freeswitch.org
>>>      <mailto:consulting at freeswitch.org>>
>>>       >>>>>>> http://www.freeswitchsolutions.com
>>>       >>>>>>>
>>>       >>>>>>>        
>>>       >>>>>>> 
>>>       >>>>>>>
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>>>       >>>>>>
>>>       >>>>>
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>>>       >>>>> 
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>>>       >>>>
>>>       >>
>>>
>>>      --
>>>      ------------------------------------------------------------
>>>      Nathan Neulinger nneul at mst.edu <mailto:nneul at mst.edu>
>>>      Missouri S&T Information Technology    (573) 612-1412
>>>      System Administrator - Architect
>>>
>>>      _________________________________________________________________________
>>>      Professional FreeSWITCH Consulting Services:
>>>      consulting at freeswitch.org <mailto:consulting at freeswitch.org>
>>>      http://www.freeswitchsolutions.com
>>>
>>>      
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>>>
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>>>
>>>
>>> --
>>> Anthony Minessale II
>>>
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>>
>
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-- 
------------------------------------------------------------
Nathan Neulinger                       nneul at mst.edu
Missouri S&T Information Technology    (573) 612-1412
System Administrator - Architect



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