RE: [Xen-devel] Creating a local network within the GuestOS and r outing to an ext ernal network

["Woloszynski, Charles" <charles.woloszynski@xxxxxxxxxxx>]

Ian:

How bad is the inter-VM performance?  Are we talking about sub 10 Mbps or just not blazing given that it is really a memory-net?

Is there any reason you can think of that IPv6 won't work with the current Xen network support?  We are going to use IPv6 (at least for off-box communications).  I am still working out the details of if/how to support QoS for applications that go off box.  One option is an application proxy on one domain and let it fully own the network interface, but that ends up being a lot of work for an essentially bent-pipe.  I suppose I could do some NAT over IPv6, .... Using the 169.254/16 for communications to the NAT point (does that have to be Domain0?) and assume that there is enough internal bandwidth (hence the above question) to avoid major performance issues until we hit the IPv6 interface (which is, by the way, a relatively slow link, < 1 Mb/s).

Charlie

Charlie Woloszynski
Innovative Concepts Inc.
703-893-2007 x506
charles.woloszynski@xxxxxxxxxxx

-----Original Message-----
From: Ian Pratt [mailto:Ian.Pratt@xxxxxxxxxxxx]
Sent: Thursday, February 19, 2004 11:46 AM
To: Woloszynski, Charles
Cc: 'xen-devel@xxxxxxxxxxxxxxxxxxxxx'; Ian.Pratt@xxxxxxxxxxxx
Subject: Re: [Xen-devel] Creating a local network within the GuestOS and routing to an ext ernal network

> Is it possible to create a local network within a set of Xenolinux
> machines and then allow one of them to route to the external network
> over an actual network interface?
>
> I am working on using the TC (traffic control) toolset to do QoS
> enforcement and planning on using Xen/Xenolinux.  Since the Xen packet
> interface simply shares access across the system, I wanted to use one
> GuestOS as the router and have it enforce the queuing policies and let
> the other GuestOSes talk to the external network through this GuestOS. 
> I was wondering if anyone has done anything like this?  Can we create
> an in-memory network for the local subnet?

Yes, the 169.254/16 network is entirely intra-machine.

There are a couple of bugs that mean that the performance of inter VM communication isn't what it should be (too many virtual interrupts), but it works. This will be fixed in somewhere in the 1.3/1.4 series when the new IO stuff goes in.

See the xen_nat_enable script (which should actually be called "dom0_nat_enable").

Ian