virt June 2014

virt@lists.centos.org

38 participants
29 discussions

Why are bridges required?
by lee 04 Jun '14

04 Jun '14

Hi, all the descriptions of networking setups with VMs I`m seeing involve bridges. The only use I see for bridges is when I actually want to be able to send network traffic to multiple arbitrary interfaces connected to the bridge. I do neither need, nor want bridges when I want to keep the VMs separated, like when separating a VM in a DMZ from a VM in the LAN. The bridge acts like a hub. Looking at [1] makes it seem that this is undesirable --- otherwise there wouldn`t be need for a software switch to prevent network traffic on a bridge from going to all of the connected interfaces. When there`s a bridge with multiple VMs connected to it, is a software switch desirable to prevent network traffic on the bridge from going to interfaces it doesn`t need to go to? If so, isn`t it better not to use a bridge to begin with? Can`t we simply have virtual interfaces on the physical host which are the "other end" of the interfaces showing up in the VMs, without bridges? [2] seems to suggest to leave all bridges "dangling", i. e. it says you`re not supposed to connect an interface to the bridge. What`s the point of a bridge when only a single interface is connected to it? [1]: http://openvswitch.org/support/config-cookbooks/vlan-configuration-cookbook/ [2]: http://wiki.libvirt.org/page/Networking -- Knowledge is volatile and fluid. Software is power.

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Re: [CentOS-virt] [Hackathon] CentOS Virt SIG summary
by Lars Kurth 03 Jun '14

03 Jun '14

Adding virt list, which we had missed off by mistake Lars On 03/06/2014 11:13, George Dunlap wrote: > Sorry this is a bit sparse; I was both running the meeting and jotting > down notes. Let me know if you have any questions. > > -George > > Present (from memory): > - George Dunlap > - Anil Madhavapeddy > - Jonathan Ludlam > - David Berrange > - Dan Keningsberg > - Dario Faggioli > - [others I've forgotten] > > > * Agenda > - Package layout > - ocaml > - oVirt? > - libvirt? > - Sorting out check-in stuff > > * ocaml and xapi > - Progess made yesterday in discussion with KB > - RHEL 7 4.0.0.1 > - xapi wants 4.0.1 > - Depend on ocaml for *building* but not for *installing* > > * Packaging > - xenstore client tools useful in domUs mixed in with libraries only > useful in dom0 > - How this would affect people upgrading? > - obsoletes? > - GWD to Mail JonL re virt sig repos > > * Build servers for SIGs? > - koji up and running? > - mock build environment > - send it to Fedora first? > - copr -- lightweight version of koji > > * oVirt > - Must be in a separate repo for dependencies' sake > - building more complicated (java, maven, &c &c) > - Start with just copying RHEV > > * libvirt > - No sense in making it a "stable" at this point > - Use the lastest release until libxl support is fully featured / stabilized

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Xen DomU supoprt in RHEL 7 and the CentOS Plan
by Karanbir Singh 03 Jun '14

03 Jun '14

Hi Guys, so far, in rhel7rc its pretty clear that Xen instances ( domUs ) are not going to boot with the RHEL7rc kernel. Also, i think at this point its a safe bet that these things wont change to GA - no way to accertain that, but its a safe bet ). Wondering if someone has looked into what the challenges might be to enable this support, and then what the options are to deliver this support ? If we can get the stuff staged up, we can work it during the Distro QA stages and target ( potentially ) a in-sync release for Xen support when CentOS7 goes GA - KB -- Karanbir Singh +44-207-0999389 | http://www.karan.org/ | twitter.com/kbsingh GnuPG Key : http://www.karan.org/publickey.asc

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Re: [CentOS-virt] xen setup documentation for centos?
by Scot P. Floess 02 Jun '14

02 Jun '14

Lee, I managed to get this working, but I'm not in front of my computer at the moment. I used KOAN and Cobbler with a few caveats...I'll try to follow up to tomorrow. Sent from my Verizon Wireless 4G LTE Smartphone -------- Original message -------- From: lee <lee(a)yun.yagibdah.de> Date:06/01/2014 8:45 PM (GMT-05:00) To: centos-virt(a)centos.org Subject: [CentOS-virt] xen setup documentation for centos? Hi, what is the proposed way to create domU guests on centos 6.5? At first I tried to follow the documentation on the xen project website which recommends using xl. I created a config file and ended up with getting a message that the kernel is not bootable when trying to create a guest. I also had to stop some daemon (xend?) because it said that xl isn`t compatible with it and the daemon must be stopped first. Then I followed redhat documentation which suggests to use virt-manager --- which doesn`t work because servers don`t have GUIs. So I finally managed to create a guest with virt-install. I can start and stop the guest (which is also running centos), though I don`t think this is the right way to create one. So how exactly are you supposed to create guests? Now I can`t get the networking to work. I`ve been reading lots of documentation and still don`t understand how that is supposed to work. As far as I understand, you get three different network interfaces: dom0: a bridge (virbr0) dom0: a virtual network interface (vifN.X) domU: a virtual network interface which doesn`t appear to be virtual to domU And dom0 keeps it`s own network interface(s), like eth0, which is a physical one. Is vifN.X the same as eth0 in domU? Or what is it for? If it`s the same, is it supposed to have the same IP on both sides? How do I make it so that domU has network access (beyond dom0)? How does this network stuff work? Do the virtual devices have to be in different subnets? When they are not, the network becomes reachable via multiple interfaces, and I`m guessing that either packet loops may be created or some paths might be disabled by STP. Do I have to set up shorewall (or the like) on dom0 to be able to handle network access for guests? Would I need to create a bridge for every guest to be able to handle them separately for firewalling purposes because otherwise packets circumvent firewall rules by directly going over the bridge? If so, why are bridges needed? I would understand doing things like adding those guests that are visible to the LAN only to the same bridge to have them all reachable likewise. When doing that, it would seem to make sense to use a different subnet for guests in the DMZ. All the documentation tells you many different things, none of them work and it`s totally confusing. Is there any /good/ documentation somewhere? -- Knowledge is volatile and fluid. Software is power. _______________________________________________ CentOS-virt mailing list CentOS-virt(a)centos.org http://lists.centos.org/mailman/listinfo/centos-virt

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virt June 2014