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

[Michael Jerris]

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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