1. Network Monitoring Russell Schwager February 18, 1998 russells@cs.cornell.edu

2. The Big Picture

3. Present Work n Use simple tools to monitor various network statistics gathered from routers and other switches. n Present the data in such a way that it will help in future research of network management.

4. Future Use of Statistics n Develop a heuristic to define hot spots and congestion in a network. n Use the heuristic to find ways to isolate and remove hot spots, making networks more stable. n Use the statistics to develop realistic simulations of networks.

5. Approach Used n A PERL script uses SNMP and queries a router using various MIB entries. n The MIB entries are stored in an input file. n The values gathered from the router are stored in a file. n The script works on both UNIX and WinNT.

6. Approach Used (cont.) n Other PERL scripts parse the data and convert it to other formats. n Currently supported formats: –HTML - The data is presented in a table format in HTML. –GNUPlot graphs - The data can be graphed. Currently the graphs are saved in pbm format because GNUPlot 3.5 is being used. (3.6 supports gif).

7. A Case Study: CSGate2 Number of Bytes ReceivedNumber of Bytes Transmitted From 2/19/98 to 2/23/98, the router CSGate2 was probed every 5 minutes recording various statistics on the data coming into and going out of the router.

8. CSGate2 - More Graphs... Out UDP DatagramsIn UDP Datagrams Out TCP SegmentsIn TCP Segments

9. Case Study: Analysis n There is some activity that occurs nightly around midnight. This could be a backup or some other system process. n The number of bytes received is a lot more than transmitted. This could indicate problems with the router. The other graphs show fairly stable traffic. Typically the number of bytes going in and out should be about equal. n The number of UDP and TCP packets are almost consistent. This could mean that services like DNS are attached to this router and not many users.

10. Further Information n Project Information: http://www.cs.cornell.edu/home/russells/meng/ n Cornell Network Research Group http://www.cs.cornell.edu/cnrg/