Sirisha Alla wrote:
> Hi,
> I was trying to use vde_switch utility and form a virtual network for
> UML instances running on multiple hosts.
> Here is my configuration:
> Two linux machines: (host1), (host2)
> On host1 did the following:
> 1) created tap0 and assigned
> 2) ran vde switch with the following commands: vde_switch -tap tap0
> -daemon -s /tmp/switch -unix /tmp/switch/ctl
you are duplicating the same option twice, that should not happen.
Either use -unix or -s, ensure that /tmp/switch is not already there.
 From now on, I will assume your switch command line is just "vde_switch
-tap tap0 -daemon -s /tmp/switch"
> On  host2 did the following:
> 1) created tap0 with192.168.0.100 ip address
> 2) ran vde switch with the following commands: vde_switch -tap tap0
> -daemon -s /tmp/switch -unix /tmp/switch/ctl
same mistake here  ^^

> - Created vde cable using dpipe vde_plug /tmp/switch/ctl = ssh host2
> vde_plug /tmp/switch/ctl on host1 and dpipe vde_plug /tmp/switch/ctl =
> ssh host1 vde_plug /tmp/switch/ctl on host2
Do you use two cables to connect two switches each other in real life
:)? Every dpipe is bidirectional, so you just need one cable with two
plugs. Try just "dpipe vde_plug /tmp/switch = ssh host2 vde_plug
/tmp/switch" on host1, and be careful to use the same path you passed in
switch creation ('ctl' is not needed, vde plugs detect control port
automatically). Also, if you used tap on both sides, you will be able to
ping the machines on the vde network.
Simply pinging from host1 should work at this point, and
should allow you to test your virtual network on your real hosts, before
actually starting the two guest machines.

Also, consider using an alternative cable: vde_cryptcab for better
network performance, or udp netcat for best if authentication and data
confidentiality are not in your primary goals, (i.e. your real network
is your LAN). Refer to manuals or find a tutorial on

As last optimization, to avoid IP fragments, shrink your tap and UML eth
MTUs to something (50 Bytes) less than the real network  ones, to allow
a cleaner encapsulation of 'virtual' ethernet frames into 'real'
transport payloads.

[uml stuff following]
> I will be happy to provide suggested logs if additional information is
> required. My requirement is that both and
> should see each other.
> Regards,
> Sirisha

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