Amitayu Das
2006-Mar-31 03:00 UTC
[Xen-users] Is # of VMs per physical host limited by bridging?
Hi, I''ve got a quick question. http://wiki.xensource.com/xenwiki/XenNetworking says that Xen creates, by default, eight pair of "connected virtual ethernet interfaces" for use by dom0. Does this mean that a. If we''re using bridging, # of VMs are limited to 8 per physical host (leaving Dom0)? or this has got nothing to do with the # of VMs running in a physical host? b. If the answer to Q(a) is "yes", then how can we have more than 8 VMs created within a single physical host? Should routing (or any other method except bridging) be adopted for the purpose of networking in such cases? Can anyone please clarify? Thanks in advance, Amitayu _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Patrick Wolfe
2006-Mar-31 13:59 UTC
Re: [Xen-users] Is # of VMs per physical host limited by bridging?
On Thu, 2006-03-30 at 22:00 -0500, Amitayu Das wrote:> I''ve got a quick question. > http://wiki.xensource.com/xenwiki/XenNetworking > says that Xen creates, by default, eight pair of "connected virtual > ethernet > interfaces" for use by dom0. Does this mean that > > a. If we''re using bridging, # of VMs are limited to 8 per physical > host (leaving Dom0)? or this has got nothing to do with the # of VMs > running in a physical host?They have nothing to do with the number of VMs you can run. The eight "virtual ethernet cables" (veth# and vif 0.#) that xen creates at boot time are not used for dom0 to connect to VMs. They exist for use by dom0 to connect to up to eight internal bridges (virtual ethernet hubs). As each VM is started, xen dynamically creates one or more NEW virtual ethernet cables between that VM and dom0 (eth0 on the VM, vif#.0 on dom0), and attaches it to a bridge, which you control in the domU''s config file vif= statement. I believe you should start out with the simplest config, using ''network-bridge'', which creates one bridge, and attaches the dom0''s eth0 physical network interface and all the VMs (including dom0) to that bridge. Once you are more comfortable with how it works, then you can try a more complex configuration, if you need to. -- Patrick Wolfe (pwolfe@employease.com) _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users