Networking under Xen

Tue Jul 14 12:36:50 UTC 2015

Hello everybody,

i have noticed some odd behaviour with networking under Xen with FreeBSD 10 as a DomU.

- IPv6 (TCP) bandwith drops from ~10 Gbit/s IPv4 to around 3 Gbit/s IPv6. (measured with iperf)

- Dropped/Stalled Connections with TCP Segmentation Offload and pf enabled.

- IPSEC-enabled Kernel TCP Performance drops from ~10 Gbit/s to ~200 Mbit/s (iperf).

I have observed this behaviour under Freebsd 10, 10.1 and 10 Stable.

The Hypervisor is running Xen 4.4 with a Linux 3.16 Dom0.

Any Suggestions?