Re: Using snmpd on host to monitor guest bandwidth usage

["Nikolai K. Bochev" <n.bochev@grandstarco.com>]

Hello,

As far as i know, you can fix the vm's interfaces on the host. I'm using libvirt and you can do it there as described in here :

http://libvirt.org/formatdomain.html#elementsNICSBridge ( What you're looking for is <target dev='vnet0'/> directive ).

If you don't do this, vnet interfaces will be assigned to vm's in the order they start - the first one getting vnet0, the second one vnet1 etc.


----- Original Message -----
From: "Neil Aggarwal" <neil@JAMMConsulting.com>
To: kvm@vger.kernel.org
Sent: Saturday, October 24, 2009 4:52:59 PM
Subject: Using snmpd on host to monitor guest bandwidth usage

Hello:

I am using Cacti to monitor traffic usage on my network.

According to what I am reading, snmpd can report traffic
stats to Cacti.

Running netstat -in on the host, I see this output:

Kernel Interface table
Iface       MTU Met    RX-OK RX-ERR RX-DRP RX-OVR    TX-OK TX-ERR TX-DRP
TX-OVR Flg
br0        1500   0   237609      0      0      0    13615      0      0
0 BMRU
eth0       1500   0   967594      0      0      0   354576      0      0
0 BMRU
lo        16436   0       63      0      0      0       63      0      0
0 LRU
virbr0     1500   0        0      0      0      0       32      0      0
0 BMRU
vnet0      1500   0    29802      0      0      0   306940      0      0
0 BMRU
vnet1      1500   0   311556      0      0      0   789331      0      0
0 BMRU

Each guest runs a bridge interface with a static IP address.
Looking at the firewall logs vnet1 is connected to guestA and
vnet0 is connected to guestB.  Will that ever change if I reboot
the host or the guests?  If it does, that would be a problem.

Are there any pitfalls of using this approach?

I am looking for a solution where I do not need to run anything
on the guests.

Thanks,
	Neil

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