If you enable RMON it will update a MIB object for the TopN ports. I forget the exact OID, but can find it if you want. In theory you could use MRTG (or other SNMP tool) to poll that mib object and display the TopN Table. However, it will not tell you what protocols or destinations these people are talking to, only that they are the highest bandwidth users. I like to know who is doing what, with whom, and with what protocols. nTop is pretty good at this IF it can see the traffic streams. My advice is to enable netflow on your aggregation points: Core routers, WAN routers, Server Farm uplinks, etc. and send them all to nTop. Or, you can SPAN the ports these devices/ports are connected to and use nTop to monitor that way. Letting nTop "capture" all the data by using SPAN will require quite a system or systems depending on your traffic load. netFlow requires far fewer resources on the nTop system and will provide the details you're looking for.
Gary >>> [EMAIL PROTECTED] 4/25/2006 1:40 PM >>> Thanks to everyone for all the advice given. Basically we've recently turned SNMP on our routers and been monitoring this with a eval version of SolarWinds Orian (which we think is great but very expensive, if anyone can recommend another product - maybe one that does SNMP monitoring and top talkers, I would be grateful!) Anyway SNMP is telling us that at certain times of the day our routers at certain sites and varying times are running really high. Now what we would like to do is be able to see who is generating this traffic. This is really were we are coming from by testing Ntop. We don't really look after the routers so we can't simply get on there and make changes or view stats so we need a third party product. >From what everyone is saying, I don't think requesting having NetFlow turned in is a good idea for us. One thing we thought could work (and I'd appreciate any thoughts on this) is maybe purchase an "Ethernet tap" such as: http://www.netoptics.com/products/product_family_details.asp?cid=1&pid=4 &Section=products&menuitem=1 and then plug our router, switch and Ntop server into this. Do you think that doing this would give us an indication of who was using our WAN traffic? Thanks again for all the help so far Andrew www.purenetworking.net -----Original Message----- From: Gary Gatten [mailto:[EMAIL PROTECTED] Sent: Tuesday, April 25, 2006 4:36 PM To: [EMAIL PROTECTED]; [email protected] Subject: Re: [Ntop] Were to placing Ntop on the network Trying to do what you want in a fully switched environment is not as easy as you might think. If you have common aggregation points, such as uplinks to server farms, WAN routers, etc. you can start there and catch most everything "important", but you still won't see "all" traffic an end node might be involved in - such as PtP with another end node on the LAN. Netflow / xflow / IPFix / whatever might work OK if your equipment supports it. Not all classes of cisco switches do. Trying to SPAN/RSPAN EVERY port would be problematic at best. You can also try implementing RMON and using the feature therein, such as Topn. Yet another option would be configuring RMON alerts and events on each port based on throughput and/or doing SNMP collections on each port using Openview, MRTG, or any of the other ten thousand SNMP utils out there. I personally use a combination of most everything I mentioned. Each approach accomplishes a slightly different goal - it seems to work OK. Guess it all depends on exactly what you want to accomplish. Define your goals and implement the best solution(s). Gary >>> [EMAIL PROTECTED] 4/25/2006 5:09:46 AM >>> Hello We are running a fully switched Cisco network and want to be able to see who are the top talkers both on our site and on remote sites. Now I've just set Ntop up had it running for a few hours. Its looks to be gathering info. We don't have NetFlow or anything like that configured on our routers. So Ntop is really just running in its default config. Would I be right in think that: a) Ntop is only reporting traffic that is on the LAN segment, it can't tell what is going on at a remote site b) The traffic is sees is only stuff that come though its network interface. So its not really giving me a true reflection of how busy the LAN is? _______________________________________________ Ntop mailing list [email protected] http://listgateway.unipi.it/mailman/listinfo/ntop _______________________________________________ Ntop mailing list [email protected] http://listgateway.unipi.it/mailman/listinfo/ntop _______________________________________________ Ntop mailing list [email protected] http://listgateway.unipi.it/mailman/listinfo/ntop
