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

[Ian Pratt <Ian.Pratt@xxxxxxxxxxxx>]

> 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?

Last time I measured I think we were only getting about 800Mb/s
with 1500 byte packets (less than we get going over a LAN !).

We should be getting multiple Gb/s.

> 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).  

The VFR in the mainline tree only supports IPv4. However, Mike
Wray has developed a L2 network switch support for Xen, which
will hopefully be checked in soon. One side effect of L2 Ethernet
MAC switching support would be that I expect IPv6 will just work
as Xen is no longer needing to look deeper than the Ethernet
header. (Xen won't be able to enforce IP firewalling for you, but
if you're passing it through a domain for NAT you can do it there
anyhow.)

> 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?) 

No, any domain can be the NAT point.

> 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).

All this will be much easier in the new IO world...

Ian


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