Re: [Discuss-gnuradio] Question about packet sequence

[Martin Braun]

On 04/14/2016 01:20 AM, Laur Joost wrote:
> 1. The sequence of the packets is important. It would be rather bad if
> two bunches of samples in your IQ stream suddenly switched places.
> 2. The host PC network stack does no reordering. It can't, by definition
> of UDP, as there's nothing to reorder by.
> 3. AFAIK, the UHD also does no reordering. However, the packets arriving
> from the USRP __are__ numbered. If UHD detects a missing packet, it*
> prints a D (to signify a Dropped packet) to stdout, and emits a new
> rx_time tag for the next packet.
> 
> * Actually, I don't know whether that's UHD or gr-uhd that does this.

It's UHD. For swapped packets, it would actually print 3 D's:

Packet sequence:   1 3 2 4

- receives 1 => OK
- receives 3 => Assumes packet was dropped, expected 2. Print D
- receives 2 => Whaaa...? Expected 4. Prints D.
- receives 4 => looks like packet 3 was dropped. Print D.

M