AS 680/682
Description, Operation and Maintenance Subsystem Description
ADS−B
2−25Ed. 10.07
SNMP is an asynchronous query/answer protocol based on the connectionless transport protocol
UDP. The controlled unit must have one or more local SNMP agents or daemons having access meth-
ods to the parameters under control.
The controlling entity is also known as SNMP manager. Both the agent and the manager have the
same description of controlled parameters within the so−called management information base
(MIB). Four transaction types are basically provided: get parameter, set parameter, get next parame-
ter and trap, the latter can be used for event oriented signaling. Most network components and com-
puter operating systems on the market are already equipped with SNMP agents and come with a spe-
cially adapted MIB. New components are made known to the SNMP manager by including their MIBs.
ADS−B Ground Stations are monitored, configured, tested and controlled using an SNMP manage-
ment program that connects to the Ground Station’s SNMP agents. SNMP covers the complete con-
figuration, operational parameters, control commands (reset, switch−over, disable output, etc.) and
the full BITE and status information (including such details as the individual tasks priorities of the SPC
software). Remote monitoring and control via SNMP is possible via the ground network in the same
way as locally.
The SNMP access is provided on a separate logical IP port. Multiple external SNMP managers can
be connected at the same line via a separate (auxiliary Ethernet interface) and/or the same physical
network connection as the operational data stream (main Ethernet interface). As the SNMP imple-
mentation allows sensitive commands and actions, a role concept with specified user access levels
and authentication is implemented. Notably for the remote software upload feature, a dedicated cyclic
redundancy check mechanism was implemented to verify data and code integrity prior to accepting
a new software from the network at the Ground Station.
The SNMP manager runs on a dedicated Remote Control and Monitoring System (RCMS), a PC−
based software application, called TSC, running under Linux Operating System. In addition to the
SNMP manager, the RCMS integrates also logging and replay tools, and an ADS−B Display.
2.4.1 Technical System Control (TSC)
See Figs. 2−27, 2−30.
The RCMS includes the Technical System Control (TSC), a dedicated SNMP manager that extends
the standard MIB by a few useful add−on functions based on a proprietary protocol. The main func-
tionality of the TSC is to monitor the state of the Ground Stations and to alarm their administrator in
case of a malfunction. In addition to that, the TSC is used to
− inspect and change all parameters of the Ground Stations
− log the system state and any configuration change to a file and a log window on screen
− manage user roles with different access rights
− allow rebooting the Ground Stations remotely
− allow updating the Ground Station software
Parameter settings, status changes and TSC user activities are time stamped and logged onto hard
disk.
The TSC provides a BITE status summary for the Ground Station as a whole and shows its operational
state (operational, maintenance, warning, fault). Parameter accessibility is managed using a user role
concept with each role having dedicated access rights (read−only, read/write, or not accessible) and
views. User access is secured using a password protected login procedure.
A complete description of parameters and screenshots of all TSC pages is given in section 4.2.
To Next Page
Loading...