Re: [9fans] Xen 3.0.3

["ron minnich" <rminnich@gmail.com>]

I am copying this xen stuff to the list as I think we need it in the archives.

I have followed the tutorial at
http://www.magma.com.ni/moin/Plan9Tutorial/XenInstall and things are
indeed better -- my venti is up and alive.

But as always, the rub with xen is the networking.

xm list shows this:
[root@q rminnich]# xm list
Name                                      ID Mem(MiB) VCPUs State   Time(s)
Domain-0                                   0      906     1 r-----    196.5
plan9                                      2       96     1 ------     89.9




and brctl shows this:
bridge name     bridge id               STP enabled     interfaces
xenbr0          8000.feffffffffff       no              peth0
                                                        vif0.0
                                                        vif2.0

So things are nicely bridged together.

With a bridge, it is as  though they're on the same wire.  Sort of.

(for those of you who don't recall, a bridge was a two-port device
that could be used as a mac-level connection between two networks. I
used to use them to isolate clusers from a main network, such that
intra-cluster traffic did not bleed off to the backbone -- this was in
the days of 10 mbit ethernet.)

At the same time, Linux bridges don't work like the good old hardware
ones, I have a thread I found long ago between me and some of the xen
guys discussing this. ...

OK, so Plan 9 is domain 2, and hence vif2.0 is the dom0 side of it:
[root@q rminnich]# ifconfig vif2.0
vif2.0    Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF
          inet6 addr: fe80::fcff:ffff:feff:ffff/64 Scope:Link
          UP BROADCAST RUNNING NOARP  MTU:1500  Metric:1
          RX packets:20 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:11520 (11.2 KiB)  TX bytes:0 (0.0 b)

note that they only give it an IPV6 adress, and it runs NOARP, a few
funny bits there.

I also do this:
[root@q rminnich]# echo 1 > /proc/sys/net/ipv4/ip_forward


an ipconfig from Plan 9 side gets this:
[root@q rminnich]# tcpdump -i vif2.0
tcpdump: WARNING: vif2.0: no IPv4 address assigned
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on vif2.0, link-type EN10MB (Ethernet), capture size 96 bytes
21:06:16.033763 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 50:6c:61:6e:39:00, length: 548
21:06:20.032192 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 50:6c:61:6e:39:00, length: 548
21:06:24.043403 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 50:6c:61:6e:39:00, length: 548


etc.

Now my wireless router is 192.168.0.1. This linux host is
192.168.0.103. So in Plan 9 dom2 I do this:
 ip/ipconfig -g 192.168.0.1 ether /net/ether0 192.168.0.99 255.255.255.0

So I make the router my gateway.

And I can now ping the 192.168.0.1, such fun.

Xen docs do recommend that you hardwire the IP for a domU, not use
dhcp, so I guess I'll do that.

What's amusing is that I can NOT ping the dom0 linux box ... i.e. the
box I am running on: tcpdump sez:
21:15:41.641627 IP 192.168.0.99 > 192.168.0.103: icmp 44: echo request seq 5857

So I've got a bit more setup to do. Once this sort of works, I will
upate the wiki.

ron