<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:st1="urn:schemas-microsoft-com:office:smarttags" xmlns="http://www.w3.org/TR/REC-html40"> <head> <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=us-ascii"> <meta name=Generator content="Microsoft Word 11 (filtered medium)"> <o:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="PersonName"/>  <style>  </style> </head> <body lang=EN-GB link=blue vlink=blue> <div class=Section1> Hi Alex,<o:p></o:p> <o:p> </o:p> Unfortunately most of our upstreams implement CPP (Control Plane Policing) to prevent DDoS attacks, which essentially means that given a certain threshold of ICMP messages the routers begin to drop those packets purposefully to avoid flooding the routers control plane. I do monitor those, but have notifications turned off because of the false positives.<o:p></o:p> <o:p> </o:p> The other problem is that one of the scenarios I see once in a while is one of our upstreams may withdraw all their BGP routes and while BGP converges we may see momentary loss to certain sites. We use BGP communities to define which provider we use for different geographic locations, so having geographic monitors is quite important for us (unfortunately, not important enough to host our own servers in those geographic locations, nor to use a performance monitoring service such as Keynote for the same).<o:p></o:p> <o:p> </o:p> Even worse, thankfully only happened just once, one of our upstreams encountered an issue where they lost connectivity, but didn’t withdraw their BGP routes from our tables. (Ouch!).<o:p></o:p> <o:p> </o:p> Cheers,<o:p></o:p> <o:p> </o:p> Giles<o:p></o:p> <o:p> </o:p> <div style='border:none;border-left:solid blue 1.5pt;padding:0cm 0cm 0cm 4.0pt'> <div> <div class=MsoNormal align=center style='text-align:center'> <hr size=2 width="100%" align=center tabindex=-1> </div> From: Alex Dehaini [mailto:alexdehaini@gmail.com] Sent: 25 January 2008 11:12 To: <st1:PersonName w:st="on">Giles Coochey</st1:PersonName>; nagios-users@lists.sourceforge.net Subject: Re: [Nagios-users] Internet Connectivity Monitoring<o:p></o:p> </div> <o:p> </o:p> We monitor our upstream provider core routers. Basically, we monitor every physical device between us and them. So, if any device goes down, we can tell where the problem is originating from.<o:p></o:p> <div> <o:p> </o:p> </div> <div> Secondly, if you have a co-located server outside your network, you can monitor that as well.<o:p></o:p> </div> <div> <o:p> </o:p> </div> <div> Alex<o:p></o:p> <div> On Jan 25, 2008 8:54 AM, <st1:PersonName w:st="on">Giles Coochey</st1:PersonName> < <a href="mailto:gcoochey@sapphire.gi">gcoochey@sapphire.gi</a>> wrote:<o:p></o:p> Hi List, As part of our Internet Connectivity monitoring I monitor a set of websites on the Internet from a diverse number of locations geographically. There are some issues with this: (a) I have to avoid sites that use Content Delivery Systems such as Akamai, because as we host such boxes ourselves the websites actually load from local servers which we host rather than the intended geographic location. Most large sites such as <a href="http://www.yahoo.com" target="_blank">www.yahoo.com</a> and <a href="http://www.google.com" target="_blank">www.google.com</a> use these content delivery systems. (b) I have to avoid small sites which often go down due to lack of redundancy in their implementation. (c) I have to avoid sites which might get pretty annoyed that I'm pulling their homepage once every 10-15 minutes just to see if I'm getting good access. I would like to hear from others on the list as to what they do to check Internet Connectivity and whether they do any smart stuff to include multiple connectivity checks as a single service check. What do you do? Thanks Giles ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. <a href="http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/" target="_blank">http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/</a> _______________________________________________ Nagios-users mailing list <a href="mailto:Nagios-users@lists.sourceforge.net">Nagios-users@lists.sourceforge.net</a> <a href="https://lists.sourceforge.net/lists/listinfo/nagios-users" target="_blank">https://lists.sourceforge.net/lists/listinfo/nagios-users </a> ::: Please include Nagios version, plugin version (-v) and OS when reporting any issue. ::: Messages without supporting info will risk being sent to /dev/null<o:p></o:p> </div> -- Alex Dehaini Developer Site - <a href="http://www.alexdehaini.com">www.alexdehaini.com</a> Email - <a href="mailto:alexdehaini@gmail.com">alexdehaini@gmail.com</a> <o:p></o:p> </div> </div> </div> </body> </html>