[Xymon] monitoring aggregated network traffic

netz-haut - stephan seitz s.seitz at netz-haut.de
Sun Oct 30 23:02:16 CET 2011


Hi,

thanks for your very helpful answer.
It took me a few days to get back to that issue, so sorry for that late responose.

I've added additional lines for outgoing, and it works as expected.

I'm absolutely fine with hardcoed interfaces, cause I need the aggregated view of
particular interfaces.


Thanks again,

Stephan





	
Am Donnerstag, den 13.10.2011, 19:42 +0200 schrieb Henrik Størner: 

	
	On 13-10-2011 16:44, netz-haut - stephan seitz wrote:
	
	> is there any "usual" way, to monitor and graph the traffic of a bulk
	> of network interfaces? The reason is, some of our hosts are connected
	> to iSCSI storages via multipath over two or four independent
	> interfaces. Since the traffic is balanced equally, every interface
	> shows (more or less) the same amount of traffic. This leads to very
	> useless rrdtool graphics as there is only one multicolored thick line
	> visible. It would be really helpful to see a graph which shows the
	> SUM of the particular interfaces.
	
	This can be done by creating an RRD graph definition to do the summation
	for you.
	
	In RRDtool, you first use one or more "DEF" lines to grab specific data
	items from one or more RRD files, and put them into some "variables".
	You can then either use these variables directly to make a line on the
	graph, or you can use them for calculating other variables via a "CDEF"
	line.
	
	The default ifstat graph has these lines:
	
	         DEF:inbytes at RRDIDX@=@RRDFN@:bytesReceived:AVERAGE
	         CDEF:in at RRDIDX@=inbytes at RRDIDX@,8,*
	
	(The @RRDIDX@ and @RRDFN@ are because this graph repeats over all the
	interfaces - Xymon replaces these with a number and the RRD filename).
	
	What this does is to first define a variable "inbytes at RRDIDX@" which has
	the "bytesReceived" value from the RRD. The it computes another
	variable, "in at RRDIDX@" as 8*inbytes - to convert from bytes to bits.
	The notation here is Reverse Polish (RPN).
	
	So if you have 4 RRD files, one for each interface, you can have RRDtool
	do the math for you like this:
	
	[ifsum]
	         TITLE Network Traffic
	         YAXIS Bits/second
	         DEF:inbytes0=ifstat.eth0.rrd:bytesReceived:AVERAGE
	         DEF:inbytes1=ifstat.eth1.rrd:bytesReceived:AVERAGE
	         DEF:inbytes2=ifstat.eth2.rrd:bytesReceived:AVERAGE
	         DEF:inbytes3=ifstat.eth3.rrd:bytesReceived:AVERAGE
	         CDEF:intotal=inbytes0,inbytes1,inbytes2,inbytes3,+,+,+
	     CDEF:inbits=intotal,8,*
	     LINE:inbits#FF0000:Aggregate inbound
	
	The "LINE" definition then uses the "inbits" value to draw a (red) line
	with this data.
	
	Have a look at graphs.cfg, and I'm sure you can figure out to add a line
	for the outgoing data also.
	
	Add "ifsum" to the GRAPHS setting in xymonserver.cfg, and the graph
	should show up on the "trends" page.
	
	
	Regards,
	Henrik
	
	PS: I haven't actually tested any of this, so feel free to provide
	corrections :-)
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