Re: [Xen-users] Monitor Network Traffic per Domain

Carsten Tolkmit
Sun, 22 May 2005 06:56:54 -0000

Hi,

>>> I was wondering if theres any way I can monitor total bytes sent
and
>>> recieved by a single Domain without installing anything on the
>>> guestos itself. I´ve been trying out a few different options but
none
>>> seem to be working out. I´m using bridged networking, each domain
has
>>> a unique public IP.
>>>
>>
>>
>> You can see the totals per guest vif using either ifconfig or cat
>> /proc/net/dev
>>
>> Ian
>>
> This works partially, but I need a way to monitor total usage over time.
> So any script that relies on statistics from each vif will get thrown
> off if I ever restart a domain or start them in a different order.

yes - I had the same problem. So I came up with the following solution:

I installed the ifrename tool (ifrename package in debian) and I changed
the /etc/xen/scripts/vif-brige script in a way that it renames the vif
before adding it to the bridge with a name based on the last byte of the
mac address assigned to the virtual interface. My changes look like this
(unified diff):

----
v-server:/etc/xen/scripts# diff -U 3 vif-bridge,vanilla vif-bridge
--- vif-bridge,vanilla  2005-05-10 12:53:40.000000000 +0200
+++ vif-bridge  2005-05-10 13:06:03.000000000 +0200
@@ -34,7 +34,7 @@
  # Exit if anything goes wrong
  set -e

-echo "vif-bridge $*"
+echo "vif-bridge $*" | /usr/bin/tee -a /var/log/vif-bridge.log

  # Operation name.
  OP=$1
@@ -74,18 +74,25 @@
      exit
  fi

+export nvif=vif-mac-`echo ${mac} | /usr/bin/awk -F '':''
''{ print $6 }''`
+
+if [ "$OP" == "up" ]; then
+    echo "request interface name ${nvif} instead of ${vif}"  |
/usr/bin/tee -a /var/log/vif-bridge.log
+    /sbin/ifrename -i ${vif} -n ${nvif}
+fi
+
  # Add/remove vif to/from bridge.
-brctl ${brcmd} ${bridge} ${vif}
-ifconfig ${vif} $OP
+brctl ${brcmd} ${bridge} ${nvif}
+ifconfig ${nvif} $OP

  if [ ${ip} ] ; then

      # If we''ve been given a list of IP networks, allow pkts with
these
src addrs.
      for addr in ${ip} ; do
-        iptables ${iptcmd} FORWARD -m physdev --physdev-in ${vif} -s
${addr} -j ACCEPT
+        iptables ${iptcmd} FORWARD -m physdev --physdev-in ${nvif} -s
${addr} -j ACCEPT
      done

      # Always allow us to talk to a DHCP server anyhow.
-    iptables ${iptcmd} FORWARD -m physdev --physdev-in ${vif} -p udp
--sport 68 --dport 67 -j ACCEPT
+    iptables ${iptcmd} FORWARD -m physdev --physdev-in ${nvif} -p udp
--sport 68 --dport 67 -j ACCEPT
  fi
----

All you have to do is to assign mac addresses in the domains that differ
by last byte, and voila, you will get the same interface name every time
the domain is started.

But take care if you use tools that will try to compansate for counter
overflows, because if you stop and start a domain, the counters will get
reset.

I then use a snmpd running in Domain-0, so that my traffic collector can
collect traffic data the same way it does from our routers.

Best regards,
Carsten