[Freeswitch-users] Fragmented IP protocol Issue with latest master and 1.4.4

Tue May 27 19:19:02 MSD 2014

That may very will only make your problems worse.

9000 bytes is the max MTU for jumbo frames on Gigabit ethernet. That
will cover Amazon's internal network but will only increase the amount
of fragmentation that will occur once you hit the Internet (typically
1500 bytes AT BEST). With the state of IP+UDP fragmentation and path
MTU discovery on the internet Mike's position is the correct one.
Squeeze what you can out of UDP with what tricks you can but switching
to TCP transport is your best bet. Most of this is covered in my blog
post here (scroll towards the bottom):

http://blog.krisk.org/2013/09/apples-new-facetime-sip-perspective.html

On Tue, May 27, 2014 at 10:39 AM, Oleg Stolyar <olegstolyar at gmail.com> wrote:
> Turns out that AWS changed the MTU on the new instance types to 9000.  They
> are still investigating the various issues this is causing but I will just
> stay on the more stable instance types for now.  Otherwise, I was all ready
> to switch to TCP.
>
>
> On Tue, May 27, 2014 at 6:38 AM, Michael Jerris <mike at jerris.com> wrote:
>>
>> If you are very close to the limit on fragments and just want to punt on
>> the problem, you can use compressed headers to squeeze a bit more out, in
>> the end, trying to fight udp fragmentation is a loosing battle at least on
>> the internet, and switching to tcp is usually the best solution that I see
>> always works.  You can also reduce the cdoecs passed along to help shrink
>> packets a bit.
>>
>> Mike
>>
>> On May 25, 2014, at 3:05 PM, Oleg Stolyar <olegstolyar at gmail.com> wrote:
>>
>> Thanks guys, I am feeling silly but hopefully this will help someone else
>> who runs into this issue.
>>
>> After you confirmed that fragmentation happens in the OS, I
>> realized/remembered that there is one more difference between the servers
>> with the old and new FreeSWITCH.  They are both AWS instances and they are
>> both CentOS 5.9 and based on the same image but different instance types.
>> So, it looks like the difference is that m3.xlarge instances work fine but a
>> little cheaper c3.xlarge have this issue.
>>
>>
>> On Sun, May 25, 2014 at 3:37 AM, Dušan Dragić <dragic.dusan at gmail.com>
>> wrote:
>>>
>>> As Peter said, look at the contents of your SIP messages, including
>>> SDP, find what changed. It's not freeswitch fragmenting the ip
>>> datagrams, it's the OS (and/or routers).
>>> As for thing to try, slim down SDP by removing some unneeded codecs ,
>>> enable compact headers in the profile etc.
>>>
>>> Search the mailing list... there have been a few fragmentation
>>> discussions.
>>>
>>> On 25 May 2014 08:41, Oleg Stolyar <olegstolyar at gmail.com> wrote:
>>> > More tests showed that what makes the difference is the size of the SIP
>>> > message FreeSWITCH returns.  If the message is 1472 bytes or less, it
>>> > works,
>>> > more than that - it does not.  1472 + 20 (IPv4 header) + 8 (UDP header)
>>> > -
>>> > 1500 which is the standard MTU size on Ethernet.
>>> >
>>> > It seems that the new master is not properly fragmenting messages, so
>>> > that
>>> > everything after the first 1500 bytes is lost.  Again - the old
>>> > FreeSWITCH
>>> > did it just fine.
>>> >
>>> > Should I file a JIRA bug for this?  Or is this a known issue?
>>> >
>>> >
>>> >
>>> > On Sat, May 24, 2014 at 11:50 AM, Oleg Stolyar <olegstolyar at gmail.com>
>>> > wrote:
>>> >>
>>> >> Now I am thinking that the Fragmented IP may be a red herring since n
>>> >> the
>>> >> old version it's also happening but only once.  Then the softphone
>>> >> acknowledges it and that's the end of it.  Something in the OK message
>>> >> from
>>> >> the current master prevents the softphone from acknowledging the OK
>>> >> message.
>>> >> I could not find significant differences in the OK message with the
>>> >> old
>>> >> version that works.  The only difference seems to be Min-SE: 120
>>> >> header in
>>> >> the old version which is missing from the new one.
>>> >>
>>> >> This is happening with at least two completely different softphone, so
>>> >> I
>>> >> can't blame the phones :-)  It's 100% reproducible.
>>> >>
>>> >> What else can I do to debug this?
>>> >>
>>> >> Any help would be greatly appreciated!
>>> >>
>>> >>
>>> >> On Fri, May 23, 2014 at 10:10 PM, Oleg Stolyar <olegstolyar at gmail.com>
>>> >> wrote:
>>> >>>
>>> >>> Hi guys,
>>> >>>
>>> >>> I upgraded to the master (and it's also happening in 1.4.4).  I have
>>> >>> some
>>> >>> very long SIP addresses in my messages.  It used to work fine on the
>>> >>> master
>>> >>> from August 2013.  However, now when FS sends back the OK message, to
>>> >>> invites with very long destination numbers, the originator softphone
>>> >>> cannot
>>> >>> receive it.  This is only happening with UDP.  TCP works fine.
>>> >>>
>>> >>> Here is a snapshot of wireshark for the master
>>> >>> https://www.dropbox.com/s/0y0m4f4t4cgnwu0/Current%20Master.PNG
>>> >>>
>>> >>> And here is the snapshot of the same OK messages for the August 2013
>>> >>> FS
>>> >>> that works
>>> >>> https://www.dropbox.com/s/7wpsyw4r2skifpb/August%202013%20Version.PNG
>>> >>>
>>> >>> Any ideas how to fix this?  Is this a known issue?
>>> >>
>>> >>
>>> >
>>> >
>>
>>
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>> 
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>
>
> _________________________________________________________________________
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> consulting at freeswitch.org
> http://www.freeswitchsolutions.com
>
> 
> 
>
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>
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-- 
Kristian Kielhofner