[c-nsp] Problem with Microsoft NLB on Server 2008 running in Multicast mode

[Peter Rathlev]

On Thu, 2010-03-25 at 10:38 -0700, Bracey, John wrote:
> Have any of you run into this issue?  If so, were you able to help out
> from the Cisco side?

I'm not sure it's the same problem, but we've had to include a static
ARP entry for the NLB cluster on the default gateway, like this:

C6k(config)# arp vrf X 10.0.0.1 03bf.0abc.def0 ARPA

This was about the router not accepting an ARP reply from a multicast
address though. You might already have been through that part.

If the problem is that the gateway won't answer ARP requests originating
from a multicast address the only sensible solution would be a static
ARP entry on the host IMHO.

And for the record: Using a multicast MAC address this way is stupid and
against the specifications. Please refer the vendor of the software to
IEEE 802.3-2008 part 1, section 3.2.3:

> 3.2.3 Address fields
> 
[...]
> 
> b) The first bit (LSB) shall be used in the Destination Address field
>    as an address type designation bit to identify the Destination
>    Address either as an individual or as a group address. If this bit
>    is 0, it shall indicate that the address field contains an
>    individual address. If this bit is 1, it shall indicate that the
>    address field contains a group address that identifies none, one or
>    more, or all of the stations connected to the LAN. In the Source
>    Address field, the first bit is reserved and set to 0.

-- 
Peter