Hello,
It turned out that the problem was caused by the checksum offload set on
virtual interfaces on the sender side.
The workaround is to set the following on host A:
docker exec rvm-tester ethtool -K eth0 tx off
So, it's definitely NOT a vpp fault. Sorry for bothering you with this issue.
--
Regards,
Laszlo Kiraly
________________________________
From: Laszlo Király
Sent: Tuesday, January 11, 2022 4:31 PM
To: vpp-dev@lists.fd.io <vpp-dev@lists.fd.io>
Subject: vlan tag rewrite failure on traffic (other side is a kernel vlan
interface)
Hello,
I am facing a problem using VLAN tag rewrite functionality on VPP.
The communication between a kernel vlan interface and a VPP VLAN sub-interface
fails. The ICMP is working but TCP/UDP packets are dropped by the kernel (just
one side - see the test description)
Find attached the detailed topology, test details, the reproduction
instructions, vpp version and 'show' commands output and tcpdump capture files
as well.
Please advise me with the way forward:
- It can be a configuration problem - what should be changed?
- Might be a fault in kernel checksum (has a low chance, but can happen)
- Can be a fault in VPP tag rewrite - can I raise a ticket? Do you need
additional information?
1. Network Topology
See attached file: topo.txt
2. Test Description
The 'Host A' should reach the 'Host B' by eth1.100 and respectively veth1
interfaces. The 'ping' works, but when trying to establish a TCP connection
(ncat/iperf) the connection fails.
2/A Client is on 'Host A'
Based on captured trace the SYN arrives to veth1 but it is dropped and does
not reach the server listening on 'host B', 'orange' nw namespace.
2/B Client is on 'Host B', 'orange' namespace
Based on trace the SYN is received and replied by the server on 'Host A'.
The SYN ACK can be seen in tcpdump, but dropped by the kernel.
Seems that the case when VPP adding VLAN tag to the packet is working but when
removing the VLAN tag from the packet the kernel drops the packet.
Based on kernel statistics the TcpInCsumErrors counter increasing, however the
VLAN is on ethernet level.
3. Reproduction Steps
See attached file: test-vtr-tcpfailure.txt
4. VPP Version and 'show' Command Outputs
See attached file: test-vtr-cmds.txt
5. Capture Files
Tcpdump captures:
ext-in-tcp-failure-sut-eth1.pcap
ext-in-tcp-failure-sut-veth1.pcap
ext-in-tcp-failure-tester.pcap
out-tcp-failure-sut-eth1.pcap
out-tcp-failure-sut-veth1.pcap
out-tcp-failure-tester.pcap
--
Laszlo Kiraly
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