[ovs-discuss] dpdk, netns and jumbo frames dropping packets

Liam Young liam.young at canonical.com
Tue Jul 9 07:34:06 UTC 2019


I have a server which has an ovs bridge with a dpdk device attached
for external network access and a network namespace attached via a tap
device. Sending data out of the namespace fails if jumbo frames are enabled.
Sending data into the namespace seems ok.  Dropping the mtu of the tap
in the network namespace to 1500 also seems to fix the issue.

I initially came across the issue in an OpenStack deployment and raised
Bug #1833713 *1. However, I was able to reproduce the issue without
OpenStack by manually creating the bridge etc *2.

Any advice, tips or you-missed-this-step very gratefully received,

Below is my setup:

Ubuntu: eoan
DPDK pkg: 18.11.1-3
OVS DPDK pkg: 2.11.0-0ubuntu2
Kerenl: 5.0.0-20-generic

root at node-licetus:~# ovs-vsctl show
    Bridge br-test
        Port "tap1"
            Interface "tap1"
                type: internal
        Port br-test
            Interface br-test
                type: internal
        Port "dpdk-nic1"
            Interface "dpdk-nic1"
                type: dpdk
                options: {dpdk-devargs="0000:03:00.0"}
    ovs_version: "2.11.0"

root at node-licetus:~# ovs-vsctl get Interface dpdk-nic1 mtu

root at node-licetus:~# ip netns exec ns1 ip addr show tap1
12: tap1: <BROADCAST,MULTICAST,PROMISC,UP,LOWER_UP> mtu 9000 qdisc fq_codel
state UNKNOWN group default qlen 1000
    link/ether 0a:dd:76:38:52:54 brd ff:ff:ff:ff:ff:ff
    inet scope global tap1
       valid_lft forever preferred_lft forever
    inet6 fe80::8dd:76ff:fe38:5254/64 scope link
       valid_lft forever preferred_lft forever

Using iperf to send data out of the netns fails:

root at node-licetus:~# ip netns exec ns1 iperf -c
Client connecting to, TCP port 5001
TCP window size: 325 KByte (default)
[ 3] local port 51590 connected with port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.3 sec 323 KBytes 257 Kbits/sec

root at node-hippalus:~# iperf -s -m
Server listening on TCP port 5001
TCP window size: 128 KByte (default)
root at node-hippalus:~#

*1 https://bugs.launchpad.net/ubuntu/+source/dpdk/+bug/1833713
*2 https://bugs.launchpad.net/ubuntu/+source/dpdk/+bug/1833713/comments/7
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