[vlc-devel] Regarding trac ticket #71

Marian Durkovic md at bts.sk
Sat Aug 20 08:51:14 CEST 2005

Hi all,

   now closed trac ticket #71 reads:

> Someone actually complained about serious reordering problems on networks
> with load-balancing routers. I just don't remember if it was with UDP (no
> solution) or RTP (live.com bug if any).

That someone was me :-)

It's not only problem in redundant network configurations, but also with
10 Gbps interfaces on e.g. Juniper M160 routers, Extreme BlackDiamond
switches, etc. 

In priciple, you can't expect an IP nework to deliver packets in the correct
order (and in case of multicast, you should also expect duplicate packets
as NORMAL behaviour due to PIM assert mechanism). 


I think this ticket should be reopened - there's no reordering
code in VLC's udp/rtp input yet, although jpsaman has introduced some
code to at least check RTP sequence numbers - but for now without the
capability to restore correct packet order. 

There's really no solution for raw UDP, and therefore I think
this format shouldn't be used for streaming unless absolutely necessary 
- if e.g. some set-top box does not understand anything else. 

Unfortunately, e.g. the Windows GUI only has the option to use raw UDP 
while RTP/UDP is missing - so most users use raw UDP even if RTP/UDP would
work better.   

	With kind regards,


----                                                                  ----
----   Marian Durkovic                       network  manager         ----
----                                                                  ----
----   Slovak Technical University           Tel: +421 2 524 51 301   ----
----   Computer Centre, Nam. Slobody 17      Fax: +421 2 524 94 351   ----
----   812 43 Bratislava, Slovak Republic    E-mail/sip: md at bts.sk    ----
----                                                                  ----

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