North American Network Operators Group

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Definition problem (was Re: Out of band monitoring of equipment)

  • From: Sean Donelan
  • Date: Wed Nov 22 01:51:59 2000

On Tue, 21 November 2000, John Leong wrote:
> Curious if any operator uses, or have interest in using, out of band
> network (e.g. modem, wireless etc.) for remote equipment (routers,
> switches, HVAC etc.) monitoring over and above doing it in band on the
> Internet.

I expect all providers, major and minor, will answer they do.  However,
this is one of those questions where everyone knows exactly what they
mean, but they may not mean what you think.

Some providers have a dedicated management network, independent of the IP
network, connected to all of their equipment: building, network, security,
servers, etc.

Some providers have a dedicated management network connected just to their
primary network boxes: routers, servers.  Some use it for monitoring and
maintenance, others only for repair and maintenance.  

Some providers have dialup (POTS) access connected to a management port
for maintenance and repair of a few critical pieces of equipment, but not
regularly used for monitoring.

Some providers have distributed systems which monitors local equipment and
send pages to local technicians.  Other providers centralize this function
in a single (and sometimes a backup) NOC.

The most common system uses an in-band method (normally SNMP and PING) for
monitoring and maintaining the network.  An out-of-band method (normally
POTS to console modems) is used for network repair activities.  Building
systems (HVAC, UPS, Fire, Security, etc) have some in-band monitoring, but
alarms are generally sent by seperate out-of-band networks.

A lot of times the decision is based on what types of systems a provider
already had in place.  But part of the difference may be due to the different
accounting and revenue practices.  In reality the distinction between "in-band"
and "out-of-band" is artificial.  The "in-band" network may be considered
the revenue-generating or production network; while the "out-of-band" network
is the network which doesn't generate revenue.  They frequently aren't as
seperate or independent as folks may think.  The out-of-band network is
often just a chunk of bandwidth you aren't using for revenue generating