> In particular the kernel may answer arp requests for one interface on the > other interface
This was exactly what we were seeing. The tap_start command was not working, so I manually set the ARP table, but with tap_start still running the kernel would set both IPs (on the same subnet) to the same MAC address, so I had to issue a tap_stop to avoid it. Now it makes sense. I have now configured the two interfaces to have different subnets, and now I can receive packets on both. Thanks! I was thinking of the ROACHes as occupying a single LAN, but would a reasonable configuration be for ROACH-to-ROACH packets to be on, say 10.0.0.x, and ROACH-to-computer packets to have different subnets, e.g. 10.0.1.x and 10.0.2.x? Thanks, Dale On Fri, Jun 14, 2013 at 1:09 PM, John Ford <[email protected]> wrote: > >> I am having a problem receiving 10gbe packets from one of the interfaces > >> on > >> a dual-port Myricom NIC. I believe the packets are properly addressed, > >> and > >> wireshark sees them fine, but programmatically we cannot receive them on > >> 10.0.0.102 via C or Python (recvfrom() just hangs), while on 10.0.0.101 > >> everything is working fine. > > > > Having two IPs on the same subnet can yield interesting results under > > linux, > > In particular the kernel may answer arp requests for one interface on the > > other interface ... > > > > Yes, we found that it doesn't work easily. I don't know the details, but > our sysadmin advised against it. We created different 10.x.x.x subnets to > use both NICs in one box, which worked fine. > > I would think there's some advanced magic that could be brought to bear, > but we didn't find it. > > John > > > regards > > > > marc > > > > >
