[ofa-general] Enabling IP_CM warns about multicast packet drops

[Sumeet Lahorani]

When we enable IB connected mode and increase MTU to 65520, we see the 
following in /var/log/messages

Feb  6 17:48:32 dadzab01 kernel: ib0: enabling connected mode will cause 
multicast packet drops
Feb  6 17:48:32 dadzab01 kernel: ib0: mtu > 2044 will cause multicast 
packet drops.
Feb  6 17:48:32 dadzab01 kernel: ib1: enabling connected mode will cause 
multicast packet drops
Feb  6 17:48:32 dadzab01 kernel: ib1: mtu > 2044 will cause multicast 
packet drops.

Should we not be doing this? What kind of multicast packets will be 
dropped?

If we are not using multicast, do any OFED drivers (bonding, ipoib etc) 
internally use multicast in a way that will cause them to not work 
correctly in connected mode?

We are using OFED 1.3.1.

- Sumeet