[Freeswitch-users] Presence Sanity Check

[Ira Tessler]

Thank you for your information. It did help!

Ira

Ira Tessler
Lead Software Engineer
ConnectMe
(732) 490-9007 x2
ira at connectmevoice.com


On Sun, Apr 7, 2013 at 12:49 PM, Cal Leeming [Simplicity Media Ltd] <
cal.leeming at simplicitymedialtd.co.uk> wrote:

> In regards to the UDP fragmentation, this is an extremely good question.
>
> Only yesterday I started to build a simple forwarding SBC in Python using
> UDP sockets, however I came up against the same theoretical problem of
> packets being larger than 1500 bytes.
>
> I've had a read through various documentation;
> http://www.rfc-ref.org/RFC-TEXTS/3261/chapter18.html
> http://www.ietf.org/rfc/rfc3428.txt
>
> https://lists.cs.columbia.edu/pipermail/sip-implementors/2006-August/013857.html
>
> http://lists.freeswitch.org/pipermail/freeswitch-users/2011-February/068372.html
>
> http://www.mail-archive.com/freeswitch-users@lists.freeswitch.org/msg05912.html
>
> Anthony has stated the following;
> *"the only reliable answer is use TCP."*
>
> There was also the option of enabling compact headers;
>
> http://lists.freeswitch.org/pipermail/freeswitch-users/2011-December/078633.html
>
> From what I can tell, there is no way to guarantee this problem won't
> happen unless you use TCP. You could reduce the packet size by compacting
> headers or removing codecs, but this would be on the assumption that every
> hop is running at 1500 MTU.
>
> Hope this helps!
>
> Cal
>
> On Sat, Apr 6, 2013 at 2:28 PM, Ira Tessler <ira at connectmevoice.com>wrote:
>
>> I just need a little guidance with the way presence works. Forgive me if
>> I am asking novice questions.
>>
>> Background (simple version)
>> We run Freeswitch in a hosted/cloud environment in a data center. We have
>> IP phones in our office on our LAN.
>>
>> That way I am understanding how Presence works, I am just learning this,
>> is that when a BLF button is programmed on a phone, that phone will send a
>> "Subscribe" message to Freeswitch. The subscriptions are stored in the
>> sip_subscriptions table (i think) in the sofia database for the sip
>> profile. When calls come in for that subscription, Freeswitch will send out
>> a NOTIFY message to the phone that subscribed in order to change the state
>> of the BLF Light.
>>
>> He is my questions/issue/confusion.
>> All our phones use UDP which has a maximum packet size of 1500 bytes.
>> When doing a sofia global siptrace on, I notice that most of the NOTIFY
>> messages are greater then 1500 bytes. That will cause packet fragmentation.
>> So if the NOTIFY message is fragmented, will it get to the phone correctly?
>> (all the time, some of the time, never??)
>>
>> If the the answer is other then ("all the time"), how do I fix this? The
>> only solution I can come up with is having my phones use TCP instead of
>> UDP. Is that the correctly solution? Did anyone else out there run into
>> this issue and if so, what is the "best practice" solution (if there is
>> one)?
>>
>> Thank you in advance!
>>
>> Ira Tessler
>> Lead Software Engineer
>> ConnectMe
>> (732) 490-9007 x2
>> ira at connectmevoice.com
>>
>> _________________________________________________________________________
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>> http://www.freeswitchsolutions.com
>>
>> 
>> 
>>
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>>
>
> _________________________________________________________________________
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> http://www.freeswitchsolutions.com
>
> 
> 
>
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>
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