[dpdk-users] rte_eth_tx_burst: Can I insert timing gaps

Philipp B philippb.ontour at gmail.com
Thu Oct 11 11:03:55 CEST 2018

Hi all!

I am working on an RTP test traffic generator. The basic idea is
clock_nanosleep providing a 20ms clock cycle to start a (big) number
of rte_eth_tx_bursts, sending equally sized buffers. As long as the
timing within a 20ms cycle is dictated primarily by the line speed, I
can be sure that not just the first buffer of each cycle has a period
of 20ms, but also the n-th buffer. (I have sent n-1 buffers before
with the same size.)

Basically, I see one 20ms interval as a series of time slots, each
capable to store an active RTP stream. My question now is, what to to
with inactive time slots? As long as all active streams are located at
consecutive time slots from the start of the 20ms interval, everything
is fine. But I cannot guarantee this.

What I need is some kind of dummy buffer, which is not transmitted but
generates a tx timing gap as a buffer of X bytes would take to be

Is such a functionality provided? As a workaround, I already thought
about sending invalid packets (bad IP Header checksum?). However, this
won't be optimal when multiple lines are aggregated.

Philipp Beyer

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