Public bug reported:
== Comment: #0 - Aniket Sahu <[email protected]> - 2026-02-03 03:56:37 ==
Problem Description:
Brought up Ubuntu 26.04 guest with two network interfaces using two different
bridges. Observed that IP is configured only for the first interface, not the
second interface, while both interfaces have DHCP ranges configured explicitly.
Guest xml snippet for interface settings pasted below:
<interface type='network'>
<mac address='52:54:00:b8:c8:8b'/>
<source network='nattest2' portid='44804ff8-7883-42bf-a8f5-9ea8c5f8b7ff'
bridge='virbr2'/>
<target dev='vnet0'/>
<model type='virtio'/>
<alias name='net0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x01'
function='0x0'/>
</interface>
<interface type='network'>
<mac address='52:54:00:42:9d:f9'/>
<source network='nattest3' portid='3a713034-7054-449e-8a84-56e7bfd4227d'
bridge='virbr3'/>
<target dev='vnet1'/>
<model type='virtio'/>
<alias name='net1'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x07'
function='0x0'/>
</interface>
System Information:
Linux ltcden6-lp4 6.18.0-8-generic #8-Ubuntu SMP PREEMPT_DYNAMIC Wed Dec 17
15:52:06 UTC 2025 ppc64le GNU/Linux
PRETTY_NAME="Ubuntu Resolute Raccoon (development branch)"
NAME="Ubuntu"
VERSION_ID="26.04"
VERSION="26.04 (Resolute Raccoon)"
VERSION_CODENAME=resolute
ID=ubuntu
ID_LIKE=debian
HOME_URL="https://www.ubuntu.com/";
SUPPORT_URL="https://help.ubuntu.com/";
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/";
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy";
UBUNTU_CODENAME=resolute
LOGO=ubuntu-logo
Logs:
root@ltcden6-lp4:~# virsh domiflist ubuntu26
Interface Type Source Model MAC
--------------------------------------------------------------
vnet0 network nattest2 virtio 52:54:00:b8:c8:8b
vnet1 network nattest3 virtio 52:54:00:42:9d:f9
root@ltcden6-lp4:~#
root@ltcden6-lp4:~# virsh net-dhcp-leases nattest2
Expiry Time MAC address Protocol IP address
Hostname Client ID or DUID
------------------------------------------------------------------------------------------------------------------------------------------------
2026-02-03 15:59:22 52:54:00:b8:c8:8b ipv4 192.168.150.213/24
ubuntu ff:f1:f5:dd:7f:00:02:00:00:ab:11:b6:0a:0e:52:01:9c:ad:6a
root@ltcden6-lp4:~# virsh net-dhcp-leases nattest3
Expiry Time MAC address Protocol IP address Hostname Client ID or
DUID
-----------------------------------------------------------------------------------
== Comment: #1 - Aniket Sahu <[email protected]> - 2026-02-03 22:30:16 ==
Please find the network definitions xml below:
nattest2:
<network>
<name>nattest2</name>
<uuid>a3eee1d9-11c9-4526-aa30-cdd953326a9c</uuid>
<forward mode='nat'>
<nat>
<port start='1024' end='65535'/>
</nat>
</forward>
<bridge name='virbr2' stp='on' delay='0'/>
<mac address='52:54:00:e1:d5:fd'/>
<ip address='192.168.150.1' netmask='255.255.255.0'>
<dhcp>
<range start='192.168.150.2' end='192.168.150.254'/>
</dhcp>
</ip>
</network>
nattest3:
<network connections='1'>
<name>nattest3</name>
<uuid>13574193-04fe-4b14-a0eb-92e6bbd1b898</uuid>
<forward mode='nat'>
<nat>
<port start='1024' end='65535'/>
</nat>
</forward>
<bridge name='virbr3' stp='on' delay='0'/>
<mac address='52:54:00:e1:d5:fd'/>
<ip address='192.168.160.1' netmask='255.255.255.0'>
<dhcp>
<range start='192.168.160.2' end='192.168.160.254'/>
</dhcp>
</ip>
</network>
== Comment: #3 - Aniket Sahu <[email protected]> - 2026-02-04 07:59:52 ==
> 1. please provide the Netplan configuration:-
> ls -l /etc/netplan/
> cat /etc/netplan/*.yaml
Please find the output below:
root@ltcden6-lp4:~# ls -l /etc/netplan && cat /etc/netplan/*
total 4
-rw------- 1 root root 353 Jan 12 14:08 00-installer-config.yaml
# This is the network config written by 'subiquity'
network:
ethernets:
ibmveth2:
addresses:
- 10.48.36.195/21
match:
macaddress: e6:31:46:fd:34:02
nameservers:
addresses:
- 9.5.175.8
search: []
routes:
- to: default
via: 10.48.32.1
set-name: ibmveth2
version: 2
> 2. Also In your provided network XMLs, both nattest2 and nattest3 are defined
> with the exact same MAC address for the bridge interface (virbr2 and virbr3).
> Can you try changing the mac address of one.
Changed the mac address on the network xml, and yet the same behaviour
is observed. Output below:
root@ltcden6-lp4:~# virsh dumpxml ubuntu26 | grep -A 10 interface
<interface type='network'>
<mac address='52:54:00:08:0d:f8'/>
<source network='nattest2' portid='4c62e6e3-48fe-4926-a60e-0925c8819b18'
bridge='virbr2'/>
<target dev='vnet8'/>
<model type='virtio'/>
<alias name='net0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x01'
function='0x0'/>
</interface>
<interface type='network'>
<mac address='52:54:00:b5:b8:87'/>
<source network='nattest3' portid='2f0f2b69-f6f6-47d7-adfa-412532a64290'
bridge='virbr3'/>
<target dev='vnet9'/>
<model type='virtio'/>
<alias name='net1'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x07'
function='0x0'/>
</interface>
<serial type='pty'>
<source path='/dev/pts/1'/>
<target type='spapr-vio-serial' port='0'>
<model name='spapr-vty'/>
</target>
<alias name='serial0'/>
<address type='spapr-vio' reg='0x30000000'/>
</serial>
<console type='pty' tty='/dev/pts/1'>
<source path='/dev/pts/1'/>
root@ltcden6-lp4:~# virsh net-dhcp-leases nattest2
Expiry Time MAC address Protocol IP address
Hostname Client ID or DUID
-----------------------------------------------------------------------------------------------------------------------------------------------
2026-02-04 20:26:05 52:54:00:08:0d:f8 ipv4 192.168.150.36/24
ubuntu ff:f1:f5:dd:7f:00:02:00:00:ab:11:b6:0a:0e:52:01:9c:ad:6a
root@ltcden6-lp4:~# virsh net-dhcp-leases nattest3
Expiry Time MAC address Protocol IP address Hostname Client ID or
DUID
-----------------------------------------------------------------------------------
root@ltcden6-lp4:~# virsh net-dumpxml nattest2
<network connections='1'>
<name>nattest2</name>
<uuid>a3eee1d9-11c9-4526-aa30-cdd953326a9c</uuid>
<forward mode='nat'>
<nat>
<port start='1024' end='65535'/>
</nat>
</forward>
<bridge name='virbr2' stp='on' delay='0'/>
<mac address='52:54:00:e1:ab:cd'/>
<ip address='192.168.150.1' netmask='255.255.255.0'>
<dhcp>
<range start='192.168.150.2' end='192.168.150.254'/>
</dhcp>
</ip>
</network>
root@ltcden6-lp4:~# virsh net-dumpxml nattest3
<network connections='1'>
<name>nattest3</name>
<uuid>c4066429-e92e-44db-a8e4-98ab880a94c2</uuid>
<forward mode='nat'>
<nat>
<port start='1024' end='65535'/>
</nat>
</forward>
<bridge name='virbr3' stp='on' delay='0'/>
<mac address='52:54:00:e1:d5:fd'/>
<ip address='192.168.160.1' netmask='255.255.255.0'>
<dhcp>
<range start='192.168.160.2' end='192.168.160.254'/>
</dhcp>
</ip>
</network>
== Comment: #6 - Aniket Sahu <[email protected]> - 2026-02-05 01:00:40 ==
With an ubuntu25 guest, the behaviour is the same
The behaviour seems to be the same on ubuntu25
root@ltcden6-lp4:/home/stuff/isos# virsh start ubuntu25test
Domain 'ubuntu25test' started
root@ltcden6-lp4:/home/stuff/isos# virsh domiflist ubuntu25test
Interface Type Source Model MAC
--------------------------------------------------------------
vnet13 network nattest2 virtio 52:54:00:49:af:f5
vnet14 network nattest3 virtio 52:54:00:a3:8a:b5
root@ltcden6-lp4:/home/stuff/isos# virsh net-dhcp-leases nattest2
Expiry Time MAC address Protocol IP address
Hostname Client ID or DUID
----------------------------------------------------------------------------------------------------------------------------------------------------
2026-02-05 12:52:11 52:54:00:08:0d:f8 ipv4 192.168.150.36/24
ubuntu ff:f1:f5:dd:7f:00:02:00:00:ab:11:b6:0a:0e:52:01:9c:ad:6a
2026-02-05 12:55:17 52:54:00:49:af:f5 ipv4 192.168.150.71/24
ubuntu25guest ff:f1:f5:dd:7f:00:02:00:00:ab:11:b3:92:fd:08:07:e2:c8:e4
root@ltcden6-lp4:/home/stuff/isos# virsh net-dhcp-leases nattest3
Expiry Time MAC address Protocol IP address Hostname Client ID or
DUID
-----------------------------------------------------------------------------------
root@ltcden6-lp4:/home/stuff/isos#
root@ltcden6-lp4:/home/stuff/isos#
root@ltcden6-lp4:/home/stuff/isos#
root@ltcden6-lp4:/home/stuff/isos# virsh dumpxml ubuntu25test | grep -A 10
"interface"
<interface type='network'>
<mac address='52:54:00:49:af:f5'/>
<source network='nattest2' portid='518a3c93-90e2-477b-808a-e9cc461da4f1'
bridge='virbr2'/>
<target dev='vnet13'/>
<model type='virtio'/>
<alias name='net0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x01'
function='0x0'/>
</interface>
<interface type='network'>
<mac address='52:54:00:a3:8a:b5'/>
<source network='nattest3' portid='e8c9af03-ec67-4bab-a03b-3068afd85ed8'
bridge='virbr3'/>
<target dev='vnet14'/>
<model type='virtio'/>
<alias name='net1'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x08'
function='0x0'/>
</interface>
<serial type='pty'>
<source path='/dev/pts/1'/>
<target type='spapr-vio-serial' port='0'>
<model name='spapr-vty'/>
</target>
<alias name='serial0'/>
<address type='spapr-vio' reg='0x30000000'/>
</serial>
<console type='pty' tty='/dev/pts/1'>
<source path='/dev/pts/1'/>
root@ltcden6-lp4:/home/stuff/isos# virsh console ubuntu25test
Connected to domain 'ubuntu25test'
Escape character is ^] (Ctrl + ])
ubuntu25guest login:
ubuntu25guest login: user
Password:
Welcome to Ubuntu 25.04 (GNU/Linux 6.14.0-37-generic ppc64le)
* Documentation: https://help.ubuntu.com
* Management: https://landscape.canonical.com
* Support: https://ubuntu.com/pro
System information as of Thu Feb 5 11:56:27 AM UTC 2026
System load: 0.15 Processes: 153
Usage of /: 29.4% of 24.43GB Users logged in: 0
Memory usage: 9% IPv4 address for enp0s1: 192.168.150.71
Swap usage: 0%
65 updates can be applied immediately.
To see these additional updates run: apt list --upgradable
user@ubuntu25guest:~$
user@ubuntu25guest:~$ sudo su
[sudo] password for user:
root@ubuntu25guest:/home/user# ls -l /etc/netplan/
total 4
-rw------- 1 root root 65 Feb 5 11:44 50-cloud-init.yaml
root@ubuntu25guest:/home/user# cat /etc/netplan/50-cloud-init.yaml
network:
version: 2
ethernets:
enp0s1:
dhcp4: true
user@ubuntu25guest:~$ cat /etc/os-release
PRETTY_NAME="Ubuntu 25.04"
NAME="Ubuntu"
VERSION_ID="25.04"
VERSION="25.04 (Plucky Puffin)"
VERSION_CODENAME=plucky
ID=ubuntu
ID_LIKE=debian
HOME_URL="https://www.ubuntu.com/";
SUPPORT_URL="https://help.ubuntu.com/";
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/";
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy";
UBUNTU_CODENAME=plucky
LOGO=ubuntu-logo
** Affects: core-network (Ubuntu)
Importance: Undecided
Assignee: Ubuntu on IBM Power Systems Bug Triage (ubuntu-power-triage)
Status: New
** Tags: architecture-ppc64le bugnameltc-217273 severity-medium
targetmilestone-inin---
** Tags added: architecture-ppc64le bugnameltc-217273 severity-medium
targetmilestone-inin---
** Changed in: ubuntu
Assignee: (unassigned) => Ubuntu on IBM Power Systems Bug Triage
(ubuntu-power-triage)
** Package changed: ubuntu => core-network (Ubuntu)
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https://bugs.launchpad.net/bugs/2140533
Title:
[Ubuntu 26.04] DHCP not working on second bridge for guest network
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