[CentOS-virt] KVM networking issue

Thu Mar 24 16:35:44 UTC 2016
Mike - st257 <silvertip257 at gmail.com>

On Tue, Mar 22, 2016 at 1:57 PM, Kevin Ross <sedecim at gmail.com> wrote:

> Hi Mike,
>
> Thanks for the info. I'd rather run monitoring such as tcpdump from
> the VM if possible and not the host as a simulation of a network
>

Then run tcpdump on the VM. Same command or commands you'd have ran on the
host node.


> appliance and with the intent eventually of giving others access to
> the VM and not the host. Here is the xml file for the private network:
>
> <!--
> WARNING: THIS IS AN AUTO-GENERATED FILE. CHANGES TO IT ARE LIKELY TO BE
> OVERWRITTEN AND LOST. Changes to this xml configuration should be made
> using:
>   virsh net-edit virbr1
> or other application using the libvirt API.
> -->
>
> <network>
>   <name>virbr1</name>
>   <uuid>####</uuid>
>   <forward mode='nat'/>
>   <bridge name='virbr1' stp='on' delay='0' />
>   <mac address='52:54:00:##:##:##'/>
>   <ip address='192.168.100.1' netmask='255.255.255.0'>
>   </ip>
> </network>
>
> There are two VMs connected to this interface, and the monitoring or
> "appliance" VM is connected to both this and the external interface.


I take it you've tried testing basic connectivity from the VMs to whatever
default gateway is in place?

I see Spanning Tree is enabled, so you might check that an interface isn't
in the blocking state.
brctl showstp <BRIDGE_INT> | egrep '^(em|eth|vnet)|state'

I don't use the NAT network mode for KVM, so hopefully someone else can
chime in on that piece.

-- 
---~~.~~---
Mike
//  SilverTip257  //
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