[j-nsp] Packet retransmissions

[Ramesh Babu Koduru]

I am using sniffer at receiving end and finding retransmissions at
receiving end.
These re transmission packets are visible even when I am doing simple
ftp from source to destination eventhough I am not sure what's causing
these re transmissions
The frequency of re transmission is 10-15mins ...

This MPLS network is an Inter continental network ( ie from India to
USA) and the RTT b/w source and destination is 290msec ....
Are these re transmissions on such a long haul network are very common?
If so ..what could be the main reasons for such re transmissions????


Thanks
Ramesh babu

>Hi All ,
>
>We are testing one broadcast video application on IP MPLS network
>RTT between Video source & receiver is 290msec . Basically we are
>transporting multiple TV Channels on MPLS network and trying to watch
>the quality at other end..........but unfortunately we see occasional
>video freezes at receiving end  and but there is no packet loss on the
>network .When I put sniffer to observe packet patterns , I observed
that
>there are packet  re transmissions on the network .Can any one here has
>experienced this kind of problem ? What could be the reason for packet
>retransmissions while I am not seeing any kind of packet loss on the
>network??

I'm not sure what the answer to your problem is, but here are a few
additional questions or things you could try to troubleshoot the
problem:

I assume that the retransmissions are coming from the video source?

Are you using the sniffer at the receiving end and seeing duplicate
packets?  Or do you have the sniffer at the transmit end and see
duplicate packets coming direclty from the source?

What transport layer is the application using?  Is there an application
layer timer that is triggering a retransmit based on a timeout?

How far apart (in time) are the duplicate packets?

                                                 dave