RHEL7: Configure aggregated network links between two RHEL systems.

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Note: This is an RHCE 7 exam objective.

Presentation

There are two ways to configure aggregated network links between two RHEL systems:

Red Hat provides a page comparing the two network links aggregation methods.

Connecting two RHEL systems directly by Ethernet cables is not supported. All connections have to be done through switches.

Concerning the tutorials, all configurations are made between virtual machines. It is also the case in the RHCE 7 exam.

Additional Resources

Venkat Nagappan‘s got an interesting video explaining how to Set up Network Teaming & Bonding in CentOS 7 (20min/2015).

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36 Comments on "RHEL7: Configure aggregated network links between two RHEL systems."

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jeromeza
Member
jeromeza

Which is faster to do in the exam and why?

Lisenet
Member

I personally find teaming configuration slightly more time consuming compared to bonding, as it requires me to either remember JSON config, or to find/copy/edit examples that are available on a RHEL server.

David_V
Member
David_V

I have a CentOS 7.2 minimal install with dual nics on vmworkstation 11.1.4 I configured bridging like Venkat did in his video above. It works until I nmcli con down bridge0-slave2. It works if I take down bridge0-slave1.. then I can put bridge0-slave2 back up and if will not work until I use nmtui to enable the connection?! I even did a yum update while it was working.. I remember Sander saying there was an issue with bridging and NetworkManager.. anyone know what is going on?

Gjorgi
Member
Gjorgi

Have you enabled promiscous and full duplex mode on the guests’ NICs?

jeromeza
Member
jeromeza

I know teaming is the new way of doing things, but I prefer bonding as I find it saves time and is quicker.

Is it allowed to use either or do we need to specifically use teaming?

dirtbag
Member
dirtbag

So I’m studying for the RHCE 7 on a CentOS 7 server and whenever I configure teaming between 2 VMs and test it with pings, I seem to always lose a bunch of packets whenever I shut off one interface of the team. I’d say there’s like a 15 second delay between when I shut off the interface and the pings to the teamed interface start working again. Is that normal? I’ve tried load-balanced and round-robin.

Lisenet
Member

That’s not normal. You should experience zero packet loss in reality.

dirtbag
Member
dirtbag

ok thats what I thought. Would it be an issue with using kvm virtual machines? I tried configuring with nmcli commands and copying the examples in /usr/share/doc/teamd-1.25/example_ifcfgs/
I get the same bad results. I looked at the time on each system and they are pretty much the same.
Not sure what else to check.

dirtbag
Member
dirtbag

ok I’m not sure why, but it seems that using the runner “activebackup” seems to work with no packets dropping. The other runners seem to take a while to “kick in” for whatever reason.

Sam
Member
Sam

I still think your problem is with the settings.
Have you tried using the debug method/log files?
There seem to be some methods from the cli or modifying the teamd.conf (see the man files).

I am not currently able to test this.
https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Networking_Guide/sec-Configure_a_Network_Team_Using-the_Command_Line.html

Sam
Member
Sam

Seems strange, I can only guess. It sounds like a setting issue. Check the resources per VM and the total resources on the host server. Check your v-lan setting. Even isolate from any external internet access. After that check NTP settings for lag and jitter.

asifshabir
Member
asifshabir

Hello Certdepot,
I am trying to configure teaming on vmware workstation … installed on Windows with single NIC (wifi) over laptop.

When I try to setup link aggregation with two cards added on to VM. It says duplicate mac address ……….

Question:
Is it possible to perform this scenario on VM?
or do I need a physical machine and two NICs with linux installed?

Lisenet
Member

Yes, it is possible to do this on a VM, I’ve personally done it many times.

asifshabir
Member
asifshabir

Below is the error that I am getting when I try to run
# nmcli connection up team0

[screen shot]
https://prnt.sc/gcxnsn

This error is vmware related …

Both the NICs work fine without team, but I receive this error as soon I bring up team interface.

Would you be able to help on this case?

Lisenet
Member

Do the adapters which are attached to the VM have different MACs?

asifshabir
Member
asifshabir

Yes, MAC Addresses are different on both cards.

I followed this guide for this issue.

https://aacable.wordpress.com/2012/12/04/howto-change-mac-address-of-vm-hosted-in-vm-workstation/

But issues still remain the same.

Output of
# ip link show
https://justpaste.it/1aj9o

Lisenet
Member

Which version of ESXi are you using?

asifshabir
Member
asifshabir

I am using VMware WorkStation 12 Pro.
version: 12.0.1

Lisenet
Member

Ah, OK, fair enough. I’m on ESXi 5.1 so this may explain why I cannot replicate your issue.

asifshabir
Member
asifshabir

Can you explain if it works with ESXi, why would it create problems with Vmware workstation … as both provide the same funtionality … that might interest me and others

Lisenet
Member

It does work on ESXi, KVM and VirtualBox, I have tested these virtualisation solutions myself when preparing for the exam. I didn’t use VMware Workstation though. They do provide similar functionality, however the way it’s achieved is a bit different – ESXi is a bare-metal hypervisor while VMware Workstation is a type 2.

asifshabir
Member
asifshabir

Thanks,
I will give it a try with Virtual Box.

BTW, your website is very informative 🙂

Lisenet
Member

Go for it. Don’t forget to set network adapters into promisc mode.

asifshabir
Member
asifshabir

Thanks
I have just finished this lab with Virtual Box, and it worked without promisc mode.

At the end it looked like issue with VMWare Workstation .

Lisenet
Member

Good stuff, really glad you got it working in the end.

DanS
Member
DanS

I understand teaming with two interfaces on a server or VM but don’t see where it’s documented or explained how to aggregate links “between” two RHEL VM’s, where is that shown?

Lisenet
Member

You need two VMs which have teaming configured with two interfaces each. The teamed link between the two servers will serve as an aggregated link between two VMs.

Sam
Member
Sam

Hmm, The Implementations used both network bonding and network teaming is aggregation. In short Set up a client and server VM, with two network interfaces each, on the same isolated network, follow the tutorial on each Server and Client VM. That should answer your question.

wpDiscuz

RHCSA7: Task of the day

Allowed time: 5 minutes.
Create a user account named "tony" with password “redhat” and belonging to a secondary group called “team”.

RHCE7: Task of the day

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Set up a caching-only DNS server to forward DNS queries.

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