Hi everyone, and happy New Year,
I am experimenting with Open vSwitch using the DPDK datapath
(datapath_type=netdev)
to analyze VXLAN tunneling behavior.
My target setup is conceptually the following:
+---------------------------+
| OVS (DPDK, userspace) |
| - VXLAN decapsulation | +---------------------------+
| - Packet analysis | | Remote traffic generator |
| - Re-encapsulation | | - Generates VXLAN traffic |
+—--------------------------+ +---------------------------+
| |
| |
| |
+--------------+ +---------------+
| dpdk0/eth |----------------------------------| eth |
+--------------+ +---------------+
Host A with OVS. Remote host with the traffic
generator.
The general idea is:
- Generate VXLAN traffic on a remote host,
- Receive it on a DPDK interface,
- Decapsulate it in OVS,
- Analyze the inner packet,
- Re-encapsulate and send it back through the VXLAN tunnel.
I tried to follow the userspace tunneling tutorial
(https://docs.openvswitch.org/en/latest/howto/userspace-tunneling/), but I am
seeing behavior that I do not fully understand.
Case 1: separate bridges (similar to the tutorial)
- DPDK interface attached to a physical bridge
- VXLAN interface attached to br-int
In this case, packet processing components (e.g., miniflow_extract) appear to
process both:
- the original VXLAN packet arriving from the DPDK interface (not decapsulated)
- the decapsulated packet coming from the VXLAN interface
Additionally, I am not able to redirect traffic back to the VXLAN interface
using a simple OpenFlow rule, while similar rules work as expected when applied
directly to the DPDK interface.
Case 2: DPDK and VXLAN interfaces on the same bridge
I also tried attaching both the DPDK interface and the VXLAN interface to the
same bridge (br-int), and steering traffic from the DPDK port to the VXLAN port
using OpenFlow rules.
In this configuration, I do not observe any packets arriving on the VXLAN
interface at all.
At this point I am unsure whether:
- This is expected behavior of VXLAN ports in the netdev/DPDK datapath, or
- I am misunderstanding how VXLAN decapsulation and reinjection into the
datapath is supposed to work in userspace OVS.
Any clarification or references would be greatly appreciated.
Thank you for your time!
Filippo
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