Greetings! In the last two days, I've had two Server 2008 machines, both with (6) NICs in bridge mode, randomly suffer a change of MAC address. I have no idea why a server would suddenly change its own MAC address. Has anyone else had this problem? No one else has access to the servers, and I'm not even sure if it's possible to change the MAC of a network bridge. It's not a huge problem but a slight annoyance to say the least because I have to update the MAC address in my DHCP server for a static reservation. Thanks. :-/

Hi shearbass, Thank you for your post. I'd like to know more information about your NIC issue listed below, additional please post ipconfig/all to clarify your issue. 1.You set up NIC Bridge via select NICs and click bridge connections? 2.All your NICs Promiscuous Mode enabled in Bridge? Run command "netsh bridge show adapter" on your server refer to KB302348. 3.When the server will change the MAC address, server reboot or ip address renew? If there are more inquiries on this issue, please feel free to let us know.Regards, Rick Tan

Hi shearbass, Thank you for your post. I'd like to know more information about your NIC issue listed below, additional please post ipconfig/all to clarify your issue. 1.You set up NIC Bridge via select NICs and click bridge connections? 2.All your NICs Promiscuous Mode enabled in Bridge? Run command "netsh bridge show adapter" on your server refer to KB302348. 3.When the server will change the MAC address, server reboot or ip address renew? If there are more inquiries on this issue, please feel free to let us know.Regards, Rick Tan

Hi shearbass, Thank you for your post. I'd like to know more information about your NIC issue listed below, additional please post ipconfig/all to clarify your issue. 1.You set up NIC Bridge via select NICs and click bridge connections? 2.All your NICs Promiscuous Mode enabled in Bridge? Run command "netsh bridge show adapter" on your server refer to KB302348. 3.When the server will change the MAC address, server reboot or ip address renew? If there are more inquiries on this issue, please feel free to let us know.Regards, Rick Tan

Has this issue been resolved? I, too, am having the same problem. The MAC address oscillates between 02-XX-XX-XX-XX-XX and 02-YY-YY-YY-YY-YY where the last 40 bits of each address are the same as the MAC addresses of the two bridged adapters. It switches on both reboot and disable/enable. Thanks in advance for any headway on this issue. Mike Pugh

c:\>netsh bridge show adapter ---------------------------------------------------------------------- ID AdapterFriendlyName ForceCompatibilityMode ---------------------------------------------------------------------- 1 Local Area Connection 4 unknown 2 Local Area Connection 3 unknown 3 Local Area Connection 2 unknown 4 Local Area Connection unknown ---------------------------------------------------------------------- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ C:\>ipconfig /all Windows IP Configuration Host Name . . . . . . . . . . . . : msserv1 Primary Dns Suffix . . . . . . . : nowata.local Node Type . . . . . . . . . . . . : Hybrid IP Routing Enabled. . . . . . . . : No WINS Proxy Enabled. . . . . . . . : No DNS Suffix Search List. . . . . . : nowata.local Ethernet adapter Network Bridge: Connection-specific DNS Suffix . : Description . . . . . . . . . . . : MAC Bridge Miniport Physical Address. . . . . . . . . : A6-BA-DB-10-84-CC DHCP Enabled. . . . . . . . . . . : No Autoconfiguration Enabled . . . . : Yes IPv4 Address. . . . . . . . . . . : 172.16.8.13(Preferred) Subnet Mask . . . . . . . . . . . : 255.255.0.0 Default Gateway . . . . . . . . . : 172.16.1.1 DNS Servers . . . . . . . . . . . : 172.16.1.10 172.16.1.11 NetBIOS over Tcpip. . . . . . . . : Enabled Tunnel adapter Local Area Connection* 9: Media State . . . . . . . . . . . : Media disconnected Connection-specific DNS Suffix . : Description . . . . . . . . . . . : Teredo Tunneling Pseudo-Interface Physical Address. . . . . . . . . : 02-00-54-55-4E-01 DHCP Enabled. . . . . . . . . . . : No Autoconfiguration Enabled . . . . : Yes Tunnel adapter Local Area Connection* 15: Media State . . . . . . . . . . . : Media disconnected Connection-specific DNS Suffix . : Description . . . . . . . . . . . : isatap.{46461C17-B1D2-4EBB-9392-09FE3BB7F 5B6} Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0 DHCP Enabled. . . . . . . . . . . : No Autoconfiguration Enabled . . . . : Yes ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I haven't really found any reason why it does this, but it only happens (sometimes) when the server reboots. I had placed a static reservation in my DHCP server, but with this trouble I decided to just go ahead and set up all of my servers with static addresses on each machine instead of DHCP. If I delete the bridge and remake it, it uses another MAC address. It doesn't always have that problem, but I'm just avoiding it now.. The MAC address seems to alternate between< a6badb1084d2> and <a6badb1084cc>, only changing the last two characters. I haven't really done anything to try and fix it since I set the IP statically. My only conclusion is that it's a software bug in Server 2008. I plan to upgrade to 2008r2 later this year anyhow. We'll see what happens. Oddly, I had another situation where (4) of my Dell R710 servers, all which had bridged connections of at least (4) NICs, all showed they had no physical connection to the network. I had to delete the bridge from all of them and leave it connected just through a single 1GBps ethernet for a few hours. Only then could I remake the bridge and have it connect properly. I had initially tried to delete and rebuild the bridge immediately and then after a reboot, but it always just showed no connection... Thanks.

c:\>netsh bridge show adapter ---------------------------------------------------------------------- ID AdapterFriendlyName ForceCompatibilityMode ---------------------------------------------------------------------- 1 Local Area Connection 4 unknown 2 Local Area Connection 3 unknown 3 Local Area Connection 2 unknown 4 Local Area Connection unknown ---------------------------------------------------------------------- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ C:\>ipconfig /all Windows IP Configuration Host Name . . . . . . . . . . . . : msserv1 Primary Dns Suffix . . . . . . . : nowata.local Node Type . . . . . . . . . . . . : Hybrid IP Routing Enabled. . . . . . . . : No WINS Proxy Enabled. . . . . . . . : No DNS Suffix Search List. . . . . . : nowata.local Ethernet adapter Network Bridge: Connection-specific DNS Suffix . : Description . . . . . . . . . . . : MAC Bridge Miniport Physical Address. . . . . . . . . : A6-BA-DB-10-84-CC DHCP Enabled. . . . . . . . . . . : No Autoconfiguration Enabled . . . . : Yes IPv4 Address. . . . . . . . . . . : 172.16.8.13(Preferred) Subnet Mask . . . . . . . . . . . : 255.255.0.0 Default Gateway . . . . . . . . . : 172.16.1.1 DNS Servers . . . . . . . . . . . : 172.16.1.10 172.16.1.11 NetBIOS over Tcpip. . . . . . . . : Enabled Tunnel adapter Local Area Connection* 9: Media State . . . . . . . . . . . : Media disconnected Connection-specific DNS Suffix . : Description . . . . . . . . . . . : Teredo Tunneling Pseudo-Interface Physical Address. . . . . . . . . : 02-00-54-55-4E-01 DHCP Enabled. . . . . . . . . . . : No Autoconfiguration Enabled . . . . : Yes Tunnel adapter Local Area Connection* 15: Media State . . . . . . . . . . . : Media disconnected Connection-specific DNS Suffix . : Description . . . . . . . . . . . : isatap.{46461C17-B1D2-4EBB-9392-09FE3BB7F 5B6} Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0 DHCP Enabled. . . . . . . . . . . : No Autoconfiguration Enabled . . . . : Yes ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I haven't really found any reason why it does this, but it only happens (sometimes) when the server reboots. I had placed a static reservation in my DHCP server, but with this trouble I decided to just go ahead and set up all of my servers with static addresses on each machine instead of DHCP. If I delete the bridge and remake it, it uses another MAC address. It doesn't always have that problem, but I'm just avoiding it now.. The MAC address seems to alternate between< a6badb1084d2> and <a6badb1084cc>, only changing the last two characters. I haven't really done anything to try and fix it since I set the IP statically. My only conclusion is that it's a software bug in Server 2008. I plan to upgrade to 2008r2 later this year anyhow. We'll see what happens. Oddly, I had another situation where (4) of my Dell R710 servers, all which had bridged connections of at least (4) NICs, all showed they had no physical connection to the network. I had to delete the bridge from all of them and leave it connected just through a single 1GBps ethernet for a few hours. Only then could I remake the bridge and have it connect properly. I had initially tried to delete and rebuild the bridge immediately and then after a reboot, but it always just showed no connection... Thanks.

c:\>netsh bridge show adapter ---------------------------------------------------------------------- ID AdapterFriendlyName ForceCompatibilityMode ---------------------------------------------------------------------- 1 Local Area Connection 4 unknown 2 Local Area Connection 3 unknown 3 Local Area Connection 2 unknown 4 Local Area Connection unknown ---------------------------------------------------------------------- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ C:\>ipconfig /all Windows IP Configuration Host Name . . . . . . . . . . . . : msserv1 Primary Dns Suffix . . . . . . . : nowata.local Node Type . . . . . . . . . . . . : Hybrid IP Routing Enabled. . . . . . . . : No WINS Proxy Enabled. . . . . . . . : No DNS Suffix Search List. . . . . . : nowata.local Ethernet adapter Network Bridge: Connection-specific DNS Suffix . : Description . . . . . . . . . . . : MAC Bridge Miniport Physical Address. . . . . . . . . : A6-BA-DB-10-84-CC DHCP Enabled. . . . . . . . . . . : No Autoconfiguration Enabled . . . . : Yes IPv4 Address. . . . . . . . . . . : 172.16.8.13(Preferred) Subnet Mask . . . . . . . . . . . : 255.255.0.0 Default Gateway . . . . . . . . . : 172.16.1.1 DNS Servers . . . . . . . . . . . : 172.16.1.10 172.16.1.11 NetBIOS over Tcpip. . . . . . . . : Enabled Tunnel adapter Local Area Connection* 9: Media State . . . . . . . . . . . : Media disconnected Connection-specific DNS Suffix . : Description . . . . . . . . . . . : Teredo Tunneling Pseudo-Interface Physical Address. . . . . . . . . : 02-00-54-55-4E-01 DHCP Enabled. . . . . . . . . . . : No Autoconfiguration Enabled . . . . : Yes Tunnel adapter Local Area Connection* 15: Media State . . . . . . . . . . . : Media disconnected Connection-specific DNS Suffix . : Description . . . . . . . . . . . : isatap.{46461C17-B1D2-4EBB-9392-09FE3BB7F 5B6} Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0 DHCP Enabled. . . . . . . . . . . : No Autoconfiguration Enabled . . . . : Yes ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I haven't really found any reason why it does this, but it only happens (sometimes) when the server reboots. I had placed a static reservation in my DHCP server, but with this trouble I decided to just go ahead and set up all of my servers with static addresses on each machine instead of DHCP. If I delete the bridge and remake it, it uses another MAC address. It doesn't always have that problem, but I'm just avoiding it now.. The MAC address seems to alternate between< a6badb1084d2> and <a6badb1084cc>, only changing the last two characters. I haven't really done anything to try and fix it since I set the IP statically. My only conclusion is that it's a software bug in Server 2008. I plan to upgrade to 2008r2 later this year anyhow. We'll see what happens. Oddly, I had another situation where (4) of my Dell R710 servers, all which had bridged connections of at least (4) NICs, all showed they had no physical connection to the network. I had to delete the bridge from all of them and leave it connected just through a single 1GBps ethernet for a few hours. Only then could I remake the bridge and have it connect properly. I had initially tried to delete and rebuild the bridge immediately and then after a reboot, but it always just showed no connection... Thanks.