GE MDS ORBIT MCR Technical Manual page 323

SCADA Back-office to Remote MCR NX+CELL redundant network setup using routing – Use Case#1
 R1 configured to terminate GRE (and IPsec)
tunnels from remotes over cell.
 Static routes configured for REMOTE#1:
10.10.6.0/24 -> towards AP (primary)
10.10.6.0/24 -> towards GRE-TUN (backup)
 Static routes configured for REMOTE#2:
10.10.7.0/24 -> towards AP (primary)
10.10.7.0/24 -> towards GRE-TUN (backup)
 Failover to Cell enabled by checking primary
route's reachability by pinging remote's NX
interface.
 NX configured as routed interface (i.e. out of
the bridge) in 192.168.1.0/24 network.
 Cell configured with APN that provides static
IP address.
 GRE configured as routed interface over Cell
 (Optional) IPsec configured over Cell to
provide security.
 Static routes configured:
10.10.1.0/24 -> NX (primary)
10.10.1.0/24 -> GRE-TUN (backup)
 Failover to Cell enabled by checking primary
route's reachability by pinging R1's interface
or by monitoring NX link status (as
facilitated by NETMON service).
Figure 3-226. SCADA Back-office to Remote MCR NX+CELL redundant setup using routing
In above use case, the SCADA back-office application sends/receives data to/from a remote asset
connected to remote MCR (called REMOTE hereafter) that has both 900 MHz radio (NX) and Cellular
radio options. The IP packets sent by back-office application to the remote asset are normally routed by
the back-office router (R1) towards MCR configured as the NX AP (called AP hereafter). The IP packets
sent by remote asset to the back-office application are normally routed by the REMOTE towards the AP.
Both R1 and REMOTE verify the primary link (NX) connectivity by sending periodic ICMP echo
requests (pings). In the event that N (configurable) successive pings are lost, both R1 and REMOTE
update their routing tables to direct traffic over cellular network instead. Both still keep checking the
primary link connectivity. Once primary link connectivity is restored (i.e. N successful pings), both R1
and REMOTE update their routing tables to direct traffic back over NX network.
The above setup on remote MCR is facilitated by following functionality available on the unit:
1. Ability to configure multiple routes towards back-office network with different preference values.
The primary route towards back-office network over NX is configured with lower preference value
(lower the value more preferred the route) than secondary route towards back-office network over
Cellular.
2. Ability to associate the primary route with verify-reachability operation, which checks the
reachability of the back-office network via this route. The reachability check is done by configuring
a NETMON service operation, which checks connectivity based on either the link status of the
primary interface (NX) or on ICMP ECHO requests (pings) towards a host reachable via the
MDS 05-6632A01, Rev. F
BACKOFFICE
192.168.1.0/24
192.168.1.4
ETH
AP
Bridge
NX
CELL
NX
REMOTE
GRE-TUN
ROUTER FUNCTION
ETH
10.10.6.0/24
RTU
MDS Orbit MCR/ECR Technical Manual
SCADA Master
10.10.1.0/24
10.150.1.1
R1
Cellular Network
NX
REMOTE
ROUTER FUNCTION
ETH
10.10.7.0/24
RTU
CELL
GRE-TUN
323