Router configuration conventions
This package uses what I call logical port names to identify
the ports in a PoP. The main advantage to using logical names is that
you can track the statistics for a given circuit or connection even
though you move it to another physical port in the same PoP, possibly
on a different router.
This package has been written with cisco routers in mind, and with a
tool to collect the logical port names from the routers, in particular
from the "description" field for each interface. For this to work,
certain conventions need to be adhered to when setting up the
description field:
- The description field is broken into several parts, divided by
", "
(comma and a single space). The logical port
name is extracted from the second such field. In our case we
use the first field to record the PTT circuit identifier in the
case of wide-area leased line ports, but what you put here or in
the third and subsequent fields (if anything) is up to you.
- The logical port names should be constructed from letters,
digits and hyphens. In particular: avoid spaces, colon, comma
and slash.
- The conventions used to name the logical ports can vary; we use
"popA-popB" for point-to-point wide-area circuits, possibly
appending a numeral if there are several parallel cuircuits
between PoPs. The circuit will be connected to two ports, in
the case above the other end (at PoP B) would be called
"popB-popA".
- For multi-access networks, e.g. LANs inside a PoP, we use the
naming convention for the logical port names of "router.lan",
where "lan" is a unique identifier for this particular
multi-access network.
The information about the mapping between "logging file name" used by
the traffic poller and the logical port names is collected and updated
once per day by the script bin/update-dbs
. This
information is recorded in a DBM database (on-disk hash from Perl).
For other routers than cisco routers, these mappings need to be
maintained manually, and the update-dbs
script needs to
be prevented from trying to collect this information. You do the
latter by listing the router names in db/manual-rtrs
. To
update the mapping information, use the bin/dbm-edit
or
the bin/dbm-dump
and the bin/dbm-load
scripts.
It is also important to adhere to a couple of other conventions when
configuring routers for this package to work well:
- The interface port speed returned via SNMP should be the same as
the physical port speed for the circuit connected to the
routers. This is so that e.g. the percentage load calculation
can be done correctly. On cisco routers this is done with the
bandwidth xxxx
configuration command.
- Once a port is taken out of operation it's IP address should be
removed, the interface should be administratively shut down, and
on a cisco router the description field should be cleared.
- If the circuit speed is upgraded (e.g. for a fractional T1 or
E1), the interface speed ought to be updated the same day to
avoid having to manually doctor raw data files after the fact
and re-run the report generation for the days/weeks/months where
the recorded data was wrong.
he@nordu.net
Last modified: Thu Jun 26 12:34:57 MET DST 1997