[Bug 1981983] Re: systemd-network changes MAC of interfaces belonging to a bond

[Launchpad Bug Tracker]

[Expired for systemd (Ubuntu) because there has been no activity for 60
days.]

** Changed in: systemd (Ubuntu)
       Status: Incomplete => Expired

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Title:
  systemd-network changes MAC of interfaces belonging to a bond

Status in systemd package in Ubuntu:
  Expired

Bug description:
  1)
  Description:    Ubuntu 20.04.4 LTS
  Release:        20.04

  2)
  systemd:
  Installed: 245.4-4ubuntu3.15

  3) What you expected to happen
  Interfaces in the bond keep their real "hardware" mac addresses. bond0 takes MAC from first interface of the bond when not explicitly set.

  4) What happened instead
  I wanted to change from ifupdown back to netplan/systemd-networkd. Thus I installed netplan.io, delete /etc/network/interfaces, purged ifupdown and wrote an yaml for netplan.

  My Yaml looks as following

  network:
    version: 2
    renderer: networkd
    ethernets:
     em1:
       dhcp4: false
       dhcp6: false
       optional: true
     em3:
       dhcp4: false
       dhcp6: false
       optional: true
    bonds:
        bond-new:
            interfaces: [em1, em3]
            dhcp4: true 
            dhcp6: false
            accept-ra: true
            link-local: [ ipv6 ]
            parameters:
                mode: 802.3ad
                mii-monitor-interval: 1

  Netplan applies it without errors. Also, this represents the (working)
  configuration I had with ifupdown.

  Now when I apply this config, bond0 gets the following (random?) MAC address: c2:ba:f9:db:xx:xx (xx for privacy)
  Also, both interfaces em1 and em3 belonging to that bond get the same MAC address. This actual "hardware" MAC address is obviously another. Strangely, all interfaces get the same MAC address:

  # ip a | grep c2:ba:f9:db:ed:4b -B 1
  2: em1: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc mq master bond-new state UP group default qlen 1000
      link/ether c2:ba:f9:db:xx:xx brd ff:ff:ff:ff:ff:ff
  4: em3: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc mq master bond-new state UP group default qlen 1000
      link/ether c2:ba:f9:db:xx:xx brd ff:ff:ff:ff:ff:ff
  --
  8: bond-new: <BROADCAST,MULTICAST,MASTER,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
      link/ether c2:ba:f9:db:xx:xx brd ff:ff:ff:ff:ff:ff

  Additionally every device added to this bond will get the same MAC
  address, e. g. em2:

  3: em2: <NO-CARRIER,BROADCAST,MULTICAST,SLAVE,UP> mtu 1500 qdisc mq master bond-new state DOWN group default qlen 1000
      link/ether c2:ba:f9:db:xx:xx brd ff:ff:ff:ff:ff:ff 

  I already set MACAddressPolicy=none in
  /lib/systemd/network/99-default.link, but it does no change this
  behavior.

  Removing an interface from the bond, does not revert the MAC. When I
  purge netplan.io and install ifupdown, the real MAC address is set to
  interfaces again.

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