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

[Oleg Stolyar]

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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