* [dpdk-dev] [Bug 418] failsafe/tap PMD drops first UDP packet
@ 2020-03-11 1:29 bugzilla
2021-02-08 16:39 ` bugzilla
0 siblings, 1 reply; 2+ messages in thread
From: bugzilla @ 2020-03-11 1:29 UTC (permalink / raw)
To: dev
https://bugs.dpdk.org/show_bug.cgi?id=418
Bug ID: 418
Summary: failsafe/tap PMD drops first UDP packet
Product: DPDK
Version: 20.02
Hardware: x86
OS: Linux
Status: UNCONFIRMED
Severity: major
Priority: Normal
Component: ethdev
Assignee: dev@dpdk.org
Reporter: stephen@networkplumber.org
Target Milestone: ---
On Azure, the first UDP packet of a flow is being dropped somewhere in the maze
of TAP PMD and Failsafe PMD. The packet arrives into the kernel device
(netvsc) and is visible with tcpdump but is lost after that. Subsequent UDP
packets get redirected to VF and have no problem.
This is a TAP/Failsafe PMD problem, and not generic to DPDK.
The Netvsc PMD does not have this problem.
The suggested fix is to use netvsc PMD instead..
To reproduce:
Setup two 8 core VMs, with accelerated networking, running Ubuntu 18.
On machine 1 run testpmd in rx only mode. My command line was:
# testpmd -l 4,5 -w 0002:00:02.0 --vdev="net_vdev_netvsc0,iface=eth1" --
--forward-mode=rxonly --stats-period=1
On machine 2 run netcat in UDP client mode.
$ nc -u 192.168.100.12 1234
Type on machine 2. The first line (packet) is lost and stat does not increment.
Second line (packet) does show up.
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