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user53747
Asked: 2010-12-03 20:32:33 +0800 CST

MAC address for DHCP when using bridge with 2 NICs?

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I have a Ubuntu system with 2 NICs where I want to create a bridge br0 and bind both NICs to that bridge using the bridge_ports eth0 eth1 option.

I also want to configure the bridge to get an IP address from the local DHCP server.

I think I know how to do this, but I wonder which MAC address(es) will the bridge send out when requesting IP settings from the DHCP server? The MAC address of eht0, eth1, both?

Thanks, Carsten

dhcp bridge

1 Answers

  1. Best Answer

    The brctl command used to set up the bridge creates a virtual interface that shows up in ifconfig. The default address is the interface with the lowest MAC address. Thus, a NIC with a mac starting with 00:50 will be picked over one starting with 00:6f. It may be possible to change the MAC address by way of ifconfig, but you may need to turn off Spanning Tree first.

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