13.5. Pitfalls
Many SNMP-capable devices change
the order of interfaces in the interfaces table
whenever a new interface card is inserted or an old one is removed.
If you run a fairly static router environment (i.e., you hardly ever
add or remove cards from your routers), the configuration examples
we've shown should work well for you. But in today's
fast-paced network environments, stability is rare. MRTG's
cfgmaker command provides a command-line option,
- -ifref, to help with this problem. It
doesn't solve the problem, but it does allow you to generate
graphs in which interfaces are labeled with their addresses,
descriptions, or names; with this information, you don't have
to remember whether interface 1 is your local network interface or
your T1 connection. Table 13-2 summarizes the usage
of - -ifref.
Table 13-2. Summary of --ifref Options
|
Option
|
Description
|
|
--ifref=ip
|
Identify each interface by its IP address.
|
|
--ifref=eth
|
Use the Ethernet address to identify the interface.
|
|
--ifref=descr
|
Use the interface description to identify the interface.
|
|
--ifref=name
|
Use the interface name to identify the interface.
|
Thus, to label interfaces with their IP addresses, run
cfgmaker like so:
[root][linuxserver] ~/mrtg-2.9.10> cfgmaker --global 'WorkDir: /mrtg/images' \
--output /mrtg/run/mrtg.cfg --ifref=ip public@router
Be sure to read the cfgmaker manual that comes
with the MRTG documentation.
 |  |  |
| 13.4. Other Data-Gathering Applications |  | 13.6. Getting Help |
Copyright © 2002 O'Reilly & Associates. All rights reserved.