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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Our network here is way larger (1500
switches, 60 routers, 1320 hosts), and we poll not only network traffic but
also stats for multicast traffic and CPU use on the core switches and routers,
all at 5min intervals. There is no discernable load on the switches from the
SNMP queries. Of course, our main switches are only on about 20% load, but
remember that these queries are only simple network traffic ones.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Note that, since SNMP is UDP traffic, and
low priority to a switch, the SNMP queries will simply be dropped in favour of
TCP traffic if a link is overloaded and not resent. You’ll get greyout on your
MRTG graphs (if using routers2) or blanks. Most switches/routers will ignore
SNMP queries in favour of forwarding packets.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>If your network is running at 85% loading
I’d say you have other more serious issues in capacity planning to deal with! If
a few SNMP queries every 5min would cause a network collapse, then you’re at
far more risk from (eg) someone opening a web browser…<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Steve<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span lang=EN-US
style='font-size:10.0pt;font-family:Tahoma;font-weight:bold'>From:</span></font></b><font
size=2 face=Tahoma><span lang=EN-US style='font-size:10.0pt;font-family:Tahoma'>
mrtg-bounces@lists.oetiker.ch [mailto:mrtg-bounces@lists.oetiker.ch] <b><span
style='font-weight:bold'>On Behalf Of </span></b>Jack Bauguer<br>
<b><span style='font-weight:bold'>Sent:</span></b> Friday, 10 October 2008
02:32<br>
<b><span style='font-weight:bold'>To:</span></b> mrtg@lists.oetiker.ch<br>
<b><span style='font-weight:bold'>Subject:</span></b> [mrtg] Can Mrtg cause a
Router to crash because of the snmp querys?</span></font><span lang=EN-US><o:p></o:p></span></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Hi,<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Im trying to build a traffic analyzer based on Mrtg here for my
company, (10 big routers 80 switches 80 servers Cisco/Nortel).<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>There was an argument about creating this Mrtg-Server, some people
claim it would be suicidal, because many of the routers and switches operates
with heavy traffic and cpu load (about 75-85%) and querying these elements
every 5 minutes would collapse the network.<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Can somebody give me some feedback on this, I personally dont believe
that querying through snmp every 5 minutes can cause such damage on the
network, even if they are on high capacity, i think maybe it could cause a
small delay on the query but nothing else, right?. I have allready worked in a
smaller enviourment and had no problems, but I need some technical arguments to
convince these guys, <o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>any ideas?<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>regards. JB<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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