mschindl
Mission Specialist
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configuring a bridge network device configuration in RHEL9

Hi,

I have a question of configuring a bridge network device configuration in RHEL9, which is not going online.

Interface br0 were created:

NAME                 UUID                                  TYPE      DEVICE 
enp2s0               79aca1f6-40da-4c79-8aa0-f0a6d39832fe  ethernet  enp2s0 
lo                   1dffc58c-8fe9-4a95-84fc-9c35e18b20c0  loopback  lo     
br0                  32838725-8e2e-4deb-ba22-f3d37e7a398f  bridge    --     
bridge-slave-enp2s0  45a4dc60-c2b0-42e7-80e2-1d2d80d3a6e4  ethernet  --


After deactivating the origin main interface enp2s0 and activating the bridge br0 with an IP address/manual, IGMP and STP disabled, it’s not going online/UP.

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: enp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether a8:a1:59:06:12:ab brd ff:ff:ff:ff:ff:ff
4: br0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default qlen 1000
    link/ether 52:d0:45:d3:22:9f brd ff:ff:ff:ff:ff:ff
    inet 10.1.1.250/24 brd 10.1.1.255 scope global noprefixroute br0
       valid_lft forever preferred_lft forever


Any idea what could be wrong here?

11 Replies
Chetan_Tiwary_
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Hello @mschindl !

Any error message that you got ? Please share some more details like history to see, nmcli dev show, nmcli con show etc. 

Did NetworkManager restart work ? Also sometimes for earlier versions if  stopping  NetworkManager and using brctl works - then you need to check the bridge.stp setting - disable it using nmcli con mod <bridge> bridge.stp off   , not sure about this setting in RHEL9.

Using a GUI / TUI tool for bridge configuration may be a little better thing to do ( personally speaking ).

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Chetan_Tiwary_
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ok for RHEL 9 , try to disable the Spanning tree STP by : 

# nmcli con modify <bridge> bridge.stp no              or

#nmcli con <bridge> stp no

and see if this helps 

 

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mschindl
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Hi @Chetan_Tiwary_ 

brctlis not installed

I want to share you my command log where not error are shown.

[root@server ~]# nmcli con show --active 

NAME    UUID                                  TYPE      DEVICE 

enp2s0  79aca1f6-40da-4c79-8aa0-f0a6d39832fe  ethernet  enp2s0 

lo      419f3524-e000-46df-934f-8020b80c2541  loopback  lo 

::::::::::::::

[root@server ~]# nmcli con add type bridge autoconnect yes con-name br0 ifname br0

Connection 'br0' (cd2a45e0-7350-469a-a267-6518a4951dd4) successfully added.

::::::::::::::

[root@server ~]# nmcli con add type bridge-slave autoconnect yes con-name enp2s0 ifname enp2s0 master br0

Warning: There is another connection with the name 'enp2s0'. Reference the connection by its uuid '1e019e69-fec5-4f11-83b8-2502d944cc9b'

Connection 'enp2s0' (1e019e69-fec5-4f11-83b8-2502d944cc9b) successfully added.

::::::::::::::

[root@server ~]# nmcli con modify br0 ipv4.addresses 10.1.1.250/24 gw4 10.1.1.254 ipv4.method manual

::::::::::::::

[root@server ~]# nmcli con modify br0 ipv4.dns 10.1.1.254

::::::::::::::

[root@server ~]# nmcli con modify br0 bridge.stp no

::::::::::::::

[root@server ~]# ip addr show

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000

    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

    inet 127.0.0.1/8 scope host lo

       valid_lft forever preferred_lft forever

    inet6 ::1/128 scope host 

       valid_lft forever preferred_lft forever

2: enp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000

    link/ether a8:a1:59:06:12:ab brd ff:ff:ff:ff:ff:ff

3: br0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default qlen 1000

    link/ether 36:34:d5:ed:6c:0e brd ff:ff:ff:ff:ff:ff

    inet 10.1.1.250/24 brd 10.1.1.255 scope global noprefixroute br0

       valid_lft forever preferred_lft forever

::::::::::::::

[root@server ~]# nmcli device show br0

GENERAL.DEVICE:                         br0

GENERAL.TYPE:                           bridge

GENERAL.HWADDR:                         36:34:D5:ED:6C:0E

GENERAL.MTU:                            1500

GENERAL.STATE:                          100 (connected)

GENERAL.CONNECTION:                     br0

GENERAL.CON-PATH:                       /org/freedesktop/NetworkManager/ActiveConnection/5

IP4.ADDRESS[1]:                         10.1.1.250/24

IP4.GATEWAY:                            10.1.1.254

IP4.ROUTE[1]:                           dst = 10.1.1.0/24, nh = 0.0.0.0, mt = 425

IP4.ROUTE[2]:                           dst = 0.0.0.0/0, nh = 10.1.1.254, mt = 425

IP4.DNS[1]:                             10.1.1.254

IP6.GATEWAY:                            --

::::::::::::::

[root@server ~]# nmcli con show --active

NAME  UUID                                  TYPE      DEVICE 

br0   cd2a45e0-7350-469a-a267-6518a4951dd4  bridge    br0    

lo    419f3524-e000-46df-934f-8020b80c2541  loopback  lo 

 

IMG_4949.jpgIMG_4950.jpg

Chetan_Tiwary_
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Ok , really difficult to troubleshoot this way without access to the console. 

However, try this once :

# nmcli con down enp2s0
# nmcli con up br0

 

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/9/html/managing_systems_using... 

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mschindl
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I did and the state is the output from „[root@server ~]# ip addr show“.

br0 is still down.

I am equally at a loss. The systems works well (A300 Asrock), but I can’t configure a bridge (for kvm).

Connecting via ssh tunnel is not useful, because I don’t have a kvm-switch and the connection is lost after changing to br0.

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mschindl
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Is there a way in RHEL to configure a plugable "USB C Ethernet Adapter" as network device ?

Duck
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I remember having significant issues doing this in RHEL 9 when I was setting up my last server. Which is odd because this was never an issue in RHEL 8 for me.

I had particular issues with setting up bonded interfaces with vlan bridges and adding docker ontop of it.

Can you show the output of nmcli con show? I think you showed it above but it shows no device associated with the bridge?

If I recal correctly, I gave up with nmcli and nmtui because I was having the same issue as you. I think I ended up doing it through Cockpit.

mschindl
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Interesting story that you was able to get it working with Cockpit.

I assigned the single physical interface as slave:

Picture: large

Following adds the interface:

::::::::::::::

[root@server ~]# nmcli con add type bridge-slave autoconnect yes con-name enp2s0 ifname enp2s0 master br0

Warning: There is another connection with the name 'enp2s0'. Reference the connection by its uuid '1e019e69-fec5-4f11-83b8-2502d944cc9b'

Connection 'enp2s0' (1e019e69-fec5-4f11-83b8-2502d944cc9b) successfully added.

::::::::::::::

 

Duck
Mission Specialist
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It seems to show no carrier for you. My understanding is that the NetworkManager doesn't manage carrier stuff, only the Kernel/drivers can do that.

The NetworkManager brings up STP by default when you make a bridge, so there might be an issue caused by that? Maybe your switch has set the port to disabled or something along those lines?

Maybe try, deleting the bridge. Bring down the physical interface to reset both the switch and Kernel connection state. Create the bridge in Cockpit while making sure span tree is disabled before enabling it?

I remember my issue had something to do with STP.

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