# Two virtual Network Interfaces on one physical Link **URL:** \ **Category:** SLES Networking\ **Created:** [August 1, 2016, 11:44am UTC](https://forums.suse.com/t/two-virtual-network-interfaces-on-one-physical-link/28469 "2016-08-01T11:44:16Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![v024302](https://avatars.discourse-cdn.com/v4/letter/v/a9adbd/32.png) [@v024302](https://forums.suse.com/u/v024302)\ **Post date:** [August 1, 2016, 11:44am UTC](https://forums.suse.com/t/two-virtual-network-interfaces-on-one-physical-link/28469/1 "2016-08-01T11:44:16Z")
Hello everyone, i have a System on SLES 11 SP1 with 4 Network-Adapters. I renamed them to eth2 (unchanged), eth3 (unchanged), ten1 (changed from eth0) and ten2 (changed from eth1). eth2 and eth3 are used for the Internet-Connection. The two ports ten1 and ten2 are connected to the Interface bond0 for Link-Aggreagrion. If i assign the IP-Address 10.90.0.16/24 to bond0 and add the Alias 1 with 10.91.0.16/16 i can ping to both Subnetworks. Now i want to create two Interfacese named eth0 and eth1. This names are not optional! eth0 should get the IP Address: 10.90.0.16/24. eth1 should get the IP Address: 10.91.0.16/16. bond0 doesn’t need an IP-Address anymore. It should just forard the Traffic from eth0 and eth1 to the real LAN. Now i want to create an internal switching between eth0, eth1 and bond0. My first idea was to create two dummy Intefaces and connect them to a transparent bridge. But the Interfaces just can ping their own IP. Does anyone know how i can handle this? If possible, i want to configure everything over Yast. But if this won’t work any other solution is also fine. ---
**Author:** ![ab1](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@ab1](https://forums.suse.com/u/ab1)\ **Post date:** [August 1, 2016, 1:51pm UTC](https://forums.suse.com/t/two-virtual-network-interfaces-on-one-physical-link/28469/2 "2016-08-01T13:51:07Z")
On 08/01/2016 02:54 AM, v024302 wrote:[color=blue] > i have a System on SLES 11 SP1 with 4 Network-Adapters. > I renamed them to eth2 (unchanged), eth3 (unchanged), ten1 (changed from > eth0) and ten2 (changed from eth1).[/color] That’s all fine; the names do not really matter to the OS, so if you want to share why the exciting rename, feel free to do so, particularly if it helps better-understand what is going on down below. [color=blue] > eth2 and eth3 are used for the Internet-Connection. > The two ports ten1 and ten2 are connected to the Interface bond0 for > Link-Aggreagrion.[/color] The names matter even less when used as slaves in a bond, so I do not understand the rename still, but oh well. [color=blue] > If i assign the IP-Address 10.90.0.16/24 to bond0 and add the Alias 1 > with 10.91.0.16/16 i can ping to both Subnetworks.[/color] That sounds like my experience too; the bond has the IP addresses and exposes them to the outside world, so everything should work assuming other protocols (ARP) and devices (switches) do their jobs properly. [color=blue] > Now i want to create two Interfacese named eth0 and eth1.[/color] Just to be clear, are you creating two new devices, or renaming the old ones back? [color=blue] > This names are not optional![/color] This is an interesting detail which I think should be explained. What you name your slaves is irrelevant, so arbitrarily specifying certain names as “not optional” raises questions such as “Why not?” which need to be answered. There could be a valid reason, but it is much more-likely that something is misunderstood, or other software is broken. [color=blue] > eth0 should get the IP Address: 10.90.0.16/24. > eth1 should get the IP Address: 10.91.0.16/16.[/color] Based on these IP addresses, I presume that the ten1 and ten2 devices from above are now gone, and these are those devices (since your machine has four (4) total devices as you stated). If these are meant to be separate devices (fifth and sixth for the system) then please clarify, particularly explaining why you have the same IPs assigned to bond0 (with its slaves ten1 and ten2) as well as to eth0 and eth1. [color=blue] > bond0 doesn’t need an IP-Address anymore. It should just forard the > Traffic from eth0 and eth1 to the real LAN.[/color] This is not, at least in my experience, how bonding works. [color=blue] > Now i want to create an internal switching between eth0, eth1 and bond0.[/color] The clarification above regarding whether or not these are new devices (fifth and sixth) or the old ones renamed back will be relevant at this point. [color=blue] > My first idea was to create two dummy Intefaces and connect them to a > transparent bridge. > But the Interfaces just can ping their own IP. > > Does anyone know how i can handle this? > > If possible, i want to configure everything over Yast. But if this won’t > work any other solution is also fine.[/color] Bonding can be configured via Yast if you use Yast to put the slave noes into ready-for-bonding mode (one of the IP address “setups” is “None (ready for bonding)” (paraphrased heavily). Using this you can then, appropriately, configure IPs for he bond device itself as you should, including alias addresses. I presume this is what you did originally, though confirmation would be appreciate. I think it is worthwhile to step back and look at the business case for all of this. Trying to setup as you are is, I believe, invalid, so what business case has you trying to use specific names for devices (eth0 and eth1), and then trying to do some internal switching among those various devices? Switching is a network layer thing, so trying to do so with a bond device (that has no IP address in your second scenario) does not make much sense either. Again, knowing why you are trying this may help us find a way to help you. My best guess is to bridge internal and external networks, and that should be fine assuming it is done properly, but your current requirements do not look correct (to me). – Good luck. If you find this post helpful and are logged into the web interface, show your appreciation and click on the star below… ---
**Author:** ![v024302](https://avatars.discourse-cdn.com/v4/letter/v/a9adbd/32.png) [@v024302](https://forums.suse.com/u/v024302)\ **Post date:** [August 1, 2016, 2:58pm UTC](https://forums.suse.com/t/two-virtual-network-interfaces-on-one-physical-link/28469/3 "2016-08-01T14:58:51Z")
Hello ab. i renamed eth0 and eth1 because i need their names later for two virtual interfaces. I want to create two new interfaces eth0 and eth1. Assign IP-Addresses to them and let bond0 send theit traffic to the real network. bond0 usese then the original interfacese eth0 (now ten1) and eth1 (now ten2) to send the traffic fom the virtual interafce to the network. To exmplane my problem in detail: in the moment i have the IP-Addresses assignt to eth0 (bevor renaming it to ten1) and eth1 (also bevor the renaming). eth0 is connected to the Server-Subnetwork 10.90.0.16/24. eth1 is connted to the Client-Subnet 10.91.0.16/16. Both Networks run over the same Switch and the same VLAN, only in seperated Subnetworks. My whole network needs both Subnetworks to work correctly. Now i connectet eth0 and eth1 to seperated Switches. These switches are Stacked, so if one fails the other managese all. The Switches are only Core-Switches and connect my Server to the End-User-Switches. I want the Network to work completly even if one Switch fails. So i bonded eth0 and eth1. Now if one Switch fails the server works fine after all. The problem: There are running many services on the Server that are hardendet to eth0 for the Server-Network and eth1 for the Client-Network. To correct all the Scripts and Config-Files would take a few days. So i want to create two virual Network-Adapters with name eth0 and eth1 that transport the whole traffic over bond0 to the Network. Therefor the existing interfaces must get another name. I simply uses ten1 and ten2, because they are 10G-SR-Addapters. ---
**Author:** ![ab1](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@ab1](https://forums.suse.com/u/ab1)\ **Post date:** [August 2, 2016, 5:33am UTC](https://forums.suse.com/t/two-virtual-network-interfaces-on-one-physical-link/28469/4 "2016-08-02T05:33:27Z")
On 08/01/2016 06:04 AM, v024302 wrote:[color=blue] > i renamed eth0 and eth1 because i need their names later for two virtual > interfaces.[/color] Usually virtual interfaces have their own naming scheme, like vnet0 or something. Still, for your reasons below, I can see why you’d avoid that. [color=blue] > I want to create two new interfaces eth0 and eth1. Assign IP-Addresses > to them and let bond0 send theit traffic to the real network. > bond0 usese then the original interfacese eth0 (now ten1) and eth1 (now > ten2) to send the traffic fom the virtual interafce to the network.[/color] Okay, so more interfaces; that’s better than the alternative, but it’s all still not how bonding is done. With bonds the network devices are merely the physical part of the “bind” device, and have minimal identity otherwise. [color=blue] > To exmplane my problem in detail: > > in the moment i have the IP-Addresses assignt to eth0 (bevor renaming it > to ten1) and eth1 (also bevor the renaming). eth0 is connected to the > Server-Subnetwork 10.90.0.16/24. eth1 is connted to the Client-Subnet > 10.91.0.16/16. > Both Networks run over the same Switch and the same VLAN, only in > seperated Subnetworks. > My whole network needs both Subnetworks to work correctly. > Now i connectet eth0 and eth1 to seperated Switches. These switches are > Stacked, so if one fails the other managese all. The Switches are only > Core-Switches and connect my Server to the End-User-Switches. > I want the Network to work completly even if one Switch fails. > > So i bonded eth0 and eth1. > Now if one Switch fails the server works fine after all.[/color] Yes, exactly, because everything works with the bond device which has all IPs, statistics, etc. hooked to it, and the NICs just happen to be there transmitting and receiving data. [color=blue] > The problem: > There are running many services on the Server that are hardendet to eth0 > for the Server-Network and eth1 for the Client-Network. > To correct all the Scripts and Config-Files would take a few days.[/color] Ah, so this is the real problem. What are these hundreds or thousands of scripts and services doing with the hard-coded stuff? If you can provide details, maybe a comprehensive set of details, we may be able to help fix that in a way that can work to avoid you trying something impossible, or wasting days on little changes. To do that, though, we need to know exactly what your scripts and services are doing, and why, and how. [color=blue] > So i want to create two virual Network-Adapters with name eth0 and eth1 > that transport the whole traffic over bond0 to the Network. Therefor the > existing interfaces must get another name. I simply uses ten1 and ten2, > because they are 10G-SR-Addapters.[/color] Even if this could work, assigning the same IP addresses to these devices is probably against all kinds of rules, and that’s what you’re trying to do per your first post, and I really doubt you can do it and have the system work properly. – Good luck. If you find this post helpful and are logged into the web interface, show your appreciation and click on the star below… ---
**Author:** ![v024302](https://avatars.discourse-cdn.com/v4/letter/v/a9adbd/32.png) [@v024302](https://forums.suse.com/u/v024302)\ **Post date:** [August 2, 2016, 10:12am UTC](https://forums.suse.com/t/two-virtual-network-interfaces-on-one-physical-link/28469/5 "2016-08-02T10:12:43Z")
Hello ab, we have servicese like squid, samba, bind, openldap, freeradius, openvp, opsi and so on. Our Network consists of 10 locations in different Cities. Each Location has it’s own Server- and Client-Network. The Networks are connected over VPN. A Masterserver Syncronises all settings to all locations. So we have many self generated Configuration-Files. For example the DNS-Config is an XML-Document with over 17000 lines of code. As you can see i would prefer to let this scripts as they are and better simulate eth0 and eth1. You say the same IP-Address on two different Interfaces? on my real interfaces ten1 and ten2 are no IP-Addressese defind. I removed the IP-Address from bond0. eth0 should get the IP 10.90.0.16/24 and eth1 the IP 10.91.0.16/16. So there are no dublicated Addresses. Now i need a way to create the virtual Interfaces eth0 and eth1, then creating a virtual switch (for example a transparent bridge) an put eth0, eth1 and bond0 together in this switch. I already now that i can create the virtual Interfaces like: ip link add eth0 type veth peer name veth0 ip link add eth1 type veth peer name veth1 ip addr add 10.90.0.16/24 dev eth0 ip addr add 10.91.0.16/16 dev eth1 ip link set eth0 up ip link set eth1 up but this solution doesn’t work over yast an on top of that i even need a way to bridge them with bond0. Thanks for your work so far. I now my problem is realy troublesome. ---
**Author:** ![ab1](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@ab1](https://forums.suse.com/u/ab1)\ **Post date:** [August 2, 2016, 5:56pm UTC](https://forums.suse.com/t/two-virtual-network-interfaces-on-one-physical-link/28469/6 "2016-08-02T17:56:29Z")
On 08/02/2016 01:14 AM, v024302 wrote:[color=blue] > Hello ab, > > we have servicese like squid, samba, bind, openldap, freeradius, openvp, > opsi and so on.[/color] Yes, but why do they care about specific ethernet devices? That’s layer one (1) and layer two (2) stuff, for services that largely operate at layer seven (7). If they are doing something interesting by looking up certain devices rather than just letting the Linux routing handle everything, it would be useful to know exactly what that is. [color=blue] > Our Network consists of 10 locations in different Cities. Each Location > has it’s own Server- and Client-Network. The Networks are connected over > VPN. > A Masterserver Syncronises all settings to all locations. So we have > many self generated Configuration-Files. For example the DNS-Config is > an XML-Document with over 17000 lines of code.[/color] That’s a nice small file; presumably in here you have things like ‘eth0’ and ‘eth1’, which you would need to replace with ‘bond0’. If that’s the case, to do so reliably you could do something like this: ```auto sed -i.bak -e 's/eth0/bond0/g' -e 's/eth1/bond0/g' /path/to/dns-config.xml ``` That may need some refinement, for example if you also have things like eth00 or eth10 or something which you would not want converted to bond00, but that’s an easy starting point. [color=blue] > As you can see i would prefer to let this scripts as they are and better > simulate eth0 and eth1.[/color] So far it seems like your options are either fixing the scripts/configuration-files/etc., or else not using bonding. [color=blue] > You say the same IP-Address on two different Interfaces? > on my real interfaces ten1 and ten2 are no IP-Addressese defind. I > removed the IP-Address from bond0. eth0 should get the IP 10.90.0.16/24 > and eth1 the IP 10.9\_1\_.0.16/16. So there are no dublicated Addresses.[/color] I thought you were assigning the IPs to both the bond as well as to the virtual NICs; I’m glad that I was mistaken. [color=blue] > Now i need a way to create the virtual Interfaces eth0 and eth1, then > creating a virtual switch (for example a transparent bridge) an put > eth0, eth1 and bond0 together in this switch.[/color] Perhaps you could do this, but you’ll need to give the bond device an address. Before pursuing this, I think we should still better-understand why things are looking up devices by eth0 and eth1; presumably they are not manipulating the devices, but instead are querying them, perhaps for IP addresses, statistics, etc. In those cases, fixing up everything to instead look for bond0 would be pretty easy, and if you do so by creating a script of the various commands, it should also be very reliable and safe. Test, of course, beforehand, but that’s something you should do in any case. – Good luck. If you find this post helpful and are logged into the web interface, show your appreciation and click on the star below… ---
**Author:** ![Jens-U](https://avatars.discourse-cdn.com/v4/letter/j/d78d45/32.png) [@Jens-U](https://forums.suse.com/u/Jens-U)\ **Post date:** [August 2, 2016, 6:25pm UTC](https://forums.suse.com/t/two-virtual-network-interfaces-on-one-physical-link/28469/7 "2016-08-02T18:25:22Z")
Hi v024302, > [… bond, bridges, dummy interfaces, IPs …] > But the [dummy] Interfaces just can ping their own IP. one of my favorite areas of problems, which I know exists but I cannot explain (didn’t yet have the time to dig into the depths): From my experience, once you’ve set an IP address to the bond interface, you run into trouble if you unset the IP and re-set it at a higher layer (i.e. the bridge or the dummy interface). I even had a case where only setting 0.0.0.0 for the bond interface already caused this. Have you restarted your server after changing the config to your target setup (bond0 via the two physicals, bridge connecting to bond0, two interfaces connecting to the bridge, each with its respective IP address)? If not, I suggest to give it a try. Do not touch the IP config of bond0 or the bridge device - if you created the bond via YaST, don’t give it an IP address at all. Once the dummy adapters have their IPs, try to ping again. Regards, J