Hi,
I'm seeing something really disturbing on our setup, which causes severe problems for us:
If you send a broadcast ARP request out using tcpreplay on the interface, the packet gets reflected back. To observe this, it's merely necessary to tcpdump on the interface that you are sending the packet out on: the link partner will receive one packet, but you will sniff two: the transmitted packet, and one that got somehow reflected back.
I've tested with another XL710 link partner and another third party link partner: this seems to happen internally on the XL710 on egress.
# tcpdump -n -i p1p1
tcpdump: WARNING: p1p1: no IPv4 address assigned
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on p1p1, link-type EN10MB (Ethernet), capture size 65535 bytes
17:47:47.135804 ARP, Request who-has 192.168.47.5 tell 192.168.47.1, length 28 <---- this one is outbound
17:47:47.135861 ARP, Request who-has 192.168.47.5 tell 192.168.47.1, length 46 <---- this one is inbound
We're using Ubuntu 14.04, with the following driver and firmware versions:
driver: i40e
version: 1.2.37
firmware-version: f4.33.31377 a1.2 n4.42 e1932
lspci says:
01:00.0 Ethernet controller [0200]: Intel Corporation Ethernet Controller LX710 for 40GbE QSFP+ [8086:1583] (rev 01)
Is there any way that this behaviour can be disabled? It causes severe problems that can escalate into packet storms for us.