MAC address 00:16:3E:35:96:9F,bridge=xenbr1,script=vif-bridge too big for destination

Issue

Due to issues with the be2net and Emulex nic, we had to switch to a different nic and the tg3 driver. At that point, we started to see the following errors:

Sep 12 16:22:01 xxxxxx libvirtd: 16:22:01.499: error : xenXMDomainConfigParse:1075 : internal error MAC address  00:16:3E:35:96:9F,bridge=xenbr1,script=vif-bridge too big for destination
Sep 12 16:22:01 xxxxxx libvirtd: 16:22:01.502: error : xenXMDomainConfigParse:1075 : internal error MAC address 00:16:3E:12:68:39 ,bridge=xenbr1,script=vif-bridge too big for destination
Sep 12 16:22:01 xxxxxx libvirtd: 16:22:01.556: error : xenXMDomainConfigParse:1075 : internal error MAC address  00:16:3E:35:96:9F,bridge=xenbr1,script=vif-bridge too big for destination
Sep 12 16:22:01 xxxxxx libvirtd: 16:22:01.558: error : xenXMDomainConfigParse:1075 : internal error MAC address 00:16:3E:12:68:39 ,bridge=xenbr1,script=vif-bridge too big for destination
Sep 12 16:22:01 xxxxxx libvirtd: 16:22:01.673: error : xenXMDomainConfigParse:1075 : internal error MAC address  00:16:3E:35:96:9F,bridge=xenbr1,script=vif-bridge too big for destination
Sep 12 16:22:01 xxxxxx libvirtd: 16:22:01.675: error : xenXMDomainConfigParse:1075 : internal error MAC address 00:16:3E:12:68:39 ,bridge=xenbr1,script=vif-bridge too big for destination
Sep 12 16:22:01 xxxxxx libvirtd: 16:22:01.730: error : xenXMDomainConfigParse:1075 : internal error MAC address  00:16:3E:35:96:9F,bridge=xenbr1,script=vif-bridge too big for destination
Sep 12 16:22:01 xxxxxx libvirtd: 16:22:01.732: error : xenXMDomainConfigParse:1075 : internal error MAC address 00:16:3E:12:68:39 ,bridge=xenbr1,script=vif-bridge too big for destination
Sep 12 16:22:01 lnhst034 libvirtd: 16:22:01.787: error : xenXMDomainConfigParse:1075 : internal error MAC address  00:16:3E:35:96:9F,bridge=xenbr1,script=vif-bridge too big for destination
Sep 12 16:22:01 lnhst034 libvirtd: 16:22:01.789: error : xenXMDomainConfigParse:1075 : internal error MAC address 00:16:3E:12:68:39 ,bridge=xenbr1,script=vif-bridge too big for destination

Please explain the cause of these errors and provide a solution to make them stop.