Re: [Xen-users] can VDE be used in Xen

[Simon Capstick <simon@xxxxxxxxxxxxxxxx>]

Simon Capstick wrote:
> Shriram Rajagopalan wrote:
> > Ah, i forgot to mention an important constraint. Assuming that this 
> > garden of vlans is going to be created in a network of xen hosts, with 
> > one switch and (I dont have administrative access /any access at all 
> > to the switch), I would be looking for a switch emulator to do the 
> > vlan trunking
> > something on the lines of VDE, Serval , etc .
> >
> > Have you or anybody for that matter had any experience with such 
> > software switch emulators (Serval sounds interesting)
> > Simon Capstick wrote:
> > > RumbelStelskin wrote:
> > > > yes, but this arrangement would create a vlan inside a single host (or
> > > > am i wrong?)..
> > > > what if i want to vlanify domUs in different hosts (hosts in different
> > > > subnets too)?
> > > > and with the added complexity of several such disparate vlans in this
> > > > network of xen hosts
> > > >
> > > >
> > > > Simon Capstick wrote:
> > > > > RumbelStelskin wrote:
> > > > > > virtual distributed ethernet
> > > > > >
> > > > > >
> > > > > > Todd Deshane wrote:
> > > > > > > what is VDE?
> > > > > > >
> > > > > > > On Jan 29, 2008 2:14 AM, RumbelStelskin <shriram@xxxxxxxxxxx 
> > > > > > > <mailto:shriram@xxxxxxxxxxx>> wrote:
> > > > > > >     i have spent the last 5 hours searching for some
> > > > > > >     post/blog/experience on
> > > > > > >     VDE Xen combo. but to no avail.
> > > > > > >
> > > > > > >     VDE seems to be popular with KVM and other non virtualized
> > > > > > >     environments
> > > > > > >     . Are there ways to use it with Xen, i mean, transparently 
> > > > > > > connect a
> > > > > > >     set of DomUs  in different physical hosts in different 
> > > > > > > networks , to
> > > > > > >     form one virtual network?
> > > > > > >
> > > > > > >     If this cannot be done at Dom0 side, it always can be done at 
> > > > > > > the DomU
> > > > > > >     side, where the domu plugs into a vde switch. But are there any
> > > > > > >     ballpark
> > > > > > >     stats on the performance drops?
> > > > > > >
> > > > > > >     to put things in a nut shell, I am looking for some decent 
> > > > > > > solution
> > > > > > >     (with acceptable levels of performance loss) to form a 
> > > > > > > virtual network
> > > > > > >     of DomUs that are spread across physical machines, across 
> > > > > > > physical
> > > > > > >     networks (some behind nats/firewalls).
> > > > > > >     is vlan the way to go?how?
> > > > > > >
> > > > > > >     thanks
> > > > > > >     r
> > > > > This is how I would go about it:
> > > > > Use vconfig on Dom0 to create a virtual interface on a VLAN, e.g. 
> > > > > eth0.1.  Then you would edit the Xen config to use that interface 
> > > > > rather than the default eth0, in bridge mode of course (the 
> > > > > default?).  Do the same on all your Dom0s and you have a shared 
> > > > > DomU network.  For security you should restrict which ports on your 
> > > > > switch can use your VLAN ID, i.e. the ones with Xen servers!  You 
> > > > > will then have to decide how to connect the VLAN to the outside 
> > > > > world, via a DomU with acting as a router or via a physical router 
> > > > > on your network.
> > > > > Simon
> > > The Xen created network bridge attached to the VLAN interface on Dom0 
> > > (not eth0) sends the appropriate traffic out to your physical network 
> > > switch.  It is my understanding that the VLAN interface is simply 
> > > tagging packets and then sending them on over the specified physical 
> > > interface (and receiving the correctly VLAN tagged packets too). 
> > > Assuming you have set-up your switch correctly and other Dom0s with 
> > > the same config then they should be able to communicate.
> > > Of course reality may bite, and you may find problems with VLANs and 
> > > Xen as discussed in posts in the list archive.  But I assume the 
> > > problems are now gone, or there are workarounds.
> > > Simon
> The only (secure) way I can think of is to set-up a Linux VPN between 
> all the Dom0s in a mesh arrangement.  Very CPU intensive I would imagine.
> It would be much better to get hold of a physical switch you can manage.
>
> Alternatively cable directly between Dom0s using cross-over cables, lots 
> of NICs and some routing on the Dom0s (not a nice solution).
> Simon
I should add that I haven't used Serval [1], but it does look interesting.

Simon
[1] http://community.igalia.com/twiki/bin/view/Serval/WebOverview


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