Channel bonding configuration for slave interface

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Hello.

I would like to ask question about the channel bonding configuration for slave interface.
I was pointed out the MAC address for the slave interface needs to be written in each
ifcfg-ethx files.

However, according to RHEL document for RHEL 6 and 7 do not have MAC address in it's example.

For RHEL 6
Example 10.2. Example ifcfg-ethX bonded interface configuration file
https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Deployment_Guide/s2-networkscripts-interfaces-chan.html

For RHEL 7
Example 4.2. Example Slave Interface Configuration File
https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Networking_Guide/sec-Network_Bonding_Using_the_Command_Line_Interface.html

Should I include the MAC address or is it just not necessary?

Best Regards,
Yu Watanabe

YW
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Responses

SW Red Hat Guru 4017 points
6 January 2016 7:51 AM

Hello

It should not be necessary, that is why the guides you linked to do not show it in the examples. If you add it, you lock the config file to a specific NIC. If someone had to replace a faulty NIC, the MAC address would change, which would prevent the bond from working until the config file was updated with the MAC for the new NIC. So please first test without MAC address.

ar Active Contributor Newbie 279 points
10 January 2016 11:46 AM

Evening,

Adding MAC address to configuration could be useful for machines with multiple NICs to ensure that the interfaces are assigned the correct device names (eg. regardless of the configured load order for each NIC's module or changes in BIOS etc..).

Please keep in mind that there is also another option (MACADDR) which is used to override MAC addresses assigned by NICs.

Regards,

-Artur.

Jamie Bainbridge's picture Red Hat Guru 7252 points
11 January 2016 3:34 AM

RHEL5 persistently named its NICs based on the HWADDR in the ifcfg- file.

RHEL6 and later do not use HWADDR to name NICs, hence specifying the interface MAC address in the ifcfg- file is not required.

YW Active Contributor 152 points
19 February 2016 5:27 AM

My apology for the late reply.

Thank you all for the reply. So if neither HWADDR nor UUID is not necessary in the ifcfg-ethX, how does the bonding module recognize which phyisical NIC to use?

Jamie Bainbridge's picture Red Hat Guru 7252 points
19 February 2016 5:33 AM

RHEL6 uses udev to name network interfaces, so the NIC has a name like ethX before the network-scripts start to load the bonding driver.

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