I'm certain that the MAC address will be the NIC in which ever server in the cluster is holding the Cluster Virtual IP address at the time. I once had a cluster'd exchange server that stopped replicating across a firewall because of an issue where the firewall notice the change in the MAC address tied to the Cluster IP and thought it was being spoofed etc and refused connections from the IP.
It took me forever to TS that one as the Firewall engineer insisted there was nothing wrong. -----Original Message----- From: Ben Scott [mailto:[email protected]] Sent: 06 January 2009 01:45 To: MS-Exchange Admin Issues Subject: Re: Does On Mon, Jan 5, 2009 at 3:28 PM, Kurt Buff <[email protected]> wrote: > All that needs to happen is for the MAC address to be unique *on the > subnet*. If you can guarantee that, it can be anything you want, aside > from all zeros. More properly, the MAC address has to be unique within the broadcast domain. For most of us, that means on all the inter-connected Ethernet switches on the same VLAN, but not across routers or point-to-point links. (P-to-P links don't even use MAC addresses, or ARP.) The MAC address cannot be all zeros, all ones (that's broadcast), or a few other reserved addresses I forget the details of. There's even a range of MAC addresses reserved for "locally administered" addressing. Back before the world settled on twisted-pair Ethernet, some NIC manufactures would assign the same MAC address to multiple cards, so long as the cards used different technologies. So you might, for example, have the same MAC address on a 10BASE-T card and a BNC or Token-Ring card. Makes things interesting on heterogeneous bridged networks. (The university campus network I started on had at least one of pretty much every network technology ever invented.) An IP address should be associated with as most one MAC address for things to work properly. Otherwise ARP will return inconsistent results, yielding bad crazyness. (A single MAC address can easily have multiple IP addresses, however.) Generically, clustering technologies often screw this up, since you've got multiple physical machines in charge of a single IP address. They cluster software is supposed to manage that, but sometimes it don't. -- Ben ~ Ninja Email Security with Cloudmark Spam Engine Gets Image Spam ~ ~ http://www.sunbeltsoftware.com/Ninja ~ ~ Ninja Email Security with Cloudmark Spam Engine Gets Image Spam ~ ~ http://www.sunbeltsoftware.com/Ninja ~
