Network Monitoring

1
Network Monitoring

• Russell Schwager
• February 18, 1998
• russells_at_cs.cornell.edu

2
The Big Picture
3
Present Work

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

4
Future Use of Statistics

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

5
Approach Used

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

6
Approach Used (cont.)

• Other PERL scripts parse the data and convert it
  to other formats.
• 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
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.
Number of Bytes Received
Number of Bytes Transmitted
8
CSGate2 - More Graphs...
Out UDP Datagrams
In UDP Datagrams
Out TCP Segments
In TCP Segments
9
Case Study Analysis

• There is some activity that occurs nightly around
  midnight. This could be a backup or some other
  system process.
• 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.
• 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

• Project Informationhttp//www.cs.cornell.edu/hom
  e/russells/meng/
• Cornell Network Research Grouphttp//www.cs.corne
  ll.edu/cnrg/