Intel E1G44ET installed in Dell R410 running Fedora with kernel 2.6.32 
x86_64 and driver igb 3.0.22 built from Intel source code.

The interface should be receiving multicast Ethernet (not IP) packets 
addressed to MAC 01:80:C2:00:00:0F, once per second. When sent to the 
motherboard Broadcom NICs, the packets are received. When sent to one of 
the Intel ports, the packets do not appear. The ports are working well 
otherwise.

The test conducted is to run tcpdump on each port independently. With 
the cable from the sending system connected to an Intel port, observe 
that the multicast packets are not seen. Move the cable to a motherboard 
port, observe that the packets are seen. The sending system is not 
altered or touched during the test. Switch back and forth as often as 
desired, the packets only appear when the wire is attached to a 
motherboard port. Other traffic appears correctly when the cable is 
attached to either port. There is no switch between the sending system 
and the system under test.

Background: This is a valid multicast MAC address. Broadcom switches use 
addresses in this range for management and treat such packets in a 
non-standard way. However, as a valid packet with a valid address, the 
packets should traverse other parts of a network unhindered.

This smells like a driver configuration issue (most likely) or a driver 
bug. However, I have not seen any driver configuration parameter that 
seems relevant. Suggestions appreciated.
-- 
Dave Close

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