[Freeswitch-users] g729 packets skipped in passthrough mode

[Steven Ayre]

They're not duplicating any packets, just setting the Marker flag on them
all.

According to the RTP RFC "It is intended to allow significant events such as
frame boundaries to be marked in the packet stream".

You generally see them on the first packet containing voice after a period
of silence. Why Huawei decided to set it on every packet is a mystery.

-Steve




On 17 February 2011 12:31, Vitalii Colosov <vetali100 at gmail.com> wrote:

> Just wondering - what is this brilliant idea which made Huawei engineers to
> setup their switch behave this way?
>
> Is there any REAL benefit? What did they try to achieve by duplicating each
> RTP packet...
>
> (Or maybe it is so strange way to assure the reliability of the traffic? At
> least one packet out of 2 will reach the destination) :)
>
>
>
>
> 2011/2/17 Javier Gallart <jgallartm at gmail.com>
>
>>  Hello
>>>
>>
>> my mistake... I had written data="RTP_BUG_IGNORE_MARK_BIT" instead of
>> value="RTP_BUG_IGNORE_MARK_BIT". It's working now. Keep this in mind if you
>> ever happen to put a Huawei SBC in from of a FS!
>>
>> Thanks
>>
>> Javier
>>
>>>
>>> ---------- Forwarded message ----------
>>> From: Javier Gallart <jgallartm at gmail.com>
>>> To: freeswitch-users at lists.freeswitch.org
>>> Date: Wed, 16 Feb 2011 13:28:35 +0100
>>> Subject: Re: [Freeswitch-users] g729 packets skipped in passthrough mode
>>> Hello,
>>>
>>> I've looked deeper into this issue and I might have hit a known problem:
>>>
>>> RTP_BUG_IGNORE_MARK_BIT = (1 << 2)
>>>
>>> /*
>>>   A Huawei SBC has been discovered that sends the mark bit on every
>>> single RTP packet.
>>>   Since this causes the RTP stack to flush it's buffers, it horribly
>>> messes up the timing on the channel.
>>>
>>>   This flag will do nothing when an inbound packet contains the mark bit.
>>>
>>>  */
>>>
>>> The carrier is actually a Huawei SBC, and the problem I reported only
>>> happens when it sends the marker bit  = true in all the rtp packets. I've
>>> tried
>>> <param name="auto-rtp-bugs" data="RTP_BUG_IGNORE_MARK_BIT"/> in the
>>> profile but the problem is still there, is this the right way to override
>>> this nonsense from the Huawei?
>>>
>>> Thanks
>>>
>>> Javier
>>>
>>>>
>>>> ---------- Forwarded message ----------
>>>> From: Anthony Minessale <anthony.minessale at gmail.com>
>>>> To: FreeSWITCH Users Help <freeswitch-users at lists.freeswitch.org>
>>>> Date: Tue, 15 Feb 2011 16:38:35 -0600
>>>> Subject: Re: [Freeswitch-users] FreeSWITCH-users Digest, Vol 56, Issue
>>>> 177
>>>> Well that's all I could think of:
>>>>
>>>> passthrough is passthrough FS never modifies anything.
>>>> you need to look harder at sip trace, pcaps or other diagnostics for
>>>> some misconfiguration.
>>>> many people use this daily.
>>>>
>>>>
>>>> On Tue, Feb 15, 2011 at 1:12 AM, Javier Gallart <jgallartm at gmail.com>
>>>> wrote:
>>>> >
>>>> > Anthony, thanks for the tip. I haven't seen any change though. I
>>>> should have
>>>> > mentioned that I'm focusing in the rtp stream coming form the callee
>>>> to the
>>>> > caller. The problem is that FS relays to the caller only half of the
>>>> packets
>>>> > received from the callee. The packets arrive at FS at a rate of 1
>>>> packet
>>>> > every 20 ms, and with a payload of 20 bytes each. Packets from FS to
>>>> the
>>>> > caller are sent every 40 ms with a payload of 20 bytes, thus skipping
>>>> half
>>>> > of the information.
>>>> >
>>>> > Thanks
>>>> >>
>>>> >> ---------- Forwarded message ----------
>>>> >> From: Anthony Minessale <anthony.minessale at gmail.com>
>>>> >> To: FreeSWITCH Users Help <freeswitch-users at lists.freeswitch.org>
>>>> >> Date: Mon, 14 Feb 2011 10:38:57 -0600
>>>> >> Subject: Re: [Freeswitch-users] g729 packets skipped in passthrough
>>>> mode
>>>> >> I bet its 20ms vs 30
>>>> >> set passthru_ptime_mismatch to true either in vars.xml or in your
>>>> >> dialplan both legs through export on the a leg or set in the a leg
>>>> and
>>>> >> in the {} on b.
>>>> >>
>>>> >>
>>>> >> On Mon, Feb 14, 2011 at 10:28 AM, Brian West <brian at freeswitch.org>
>>>> wrote:
>>>> >> > What exactly is the problem?  I see no issue here can you elaborate
>>>> on
>>>> >> > what you're seeing?
>>>> >> >
>>>> >> > /b
>>>> >> >
>>>> >> > On Feb 14, 2011, at 4:48 AM, Javier Gallart wrote:
>>>> >> >
>>>> >> >> I've tried to explicitly set ptime at 20ms at switch.conf
>>>> -although
>>>> >> >> it's not necessary afaik-. Has any one experienced this same
>>>> issue?
>>>> >> >>
>>>> >> >> Thanks in advance..
>>>> >> >>
>>>> >> >> Regards
>>>> >> >
>>>> >> >
>>>>
>>>>
>>>
>>>
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