ESR Serial-over-IP Tunneling

In several months ago, I’ve been asked to perform proof of concept by a customer who wants to deploy Serial connection over WAN. It’s because they have a Client-Server application for SCADA, which is still running on legacy protocol with Serial interface. In this session, I won’t discuss more detail about the SCADA system. However, I will show you how to transmit the Serial data over IP with Enterprise Service Router (ESR) to provide connectivity between RTU on remote site and the SCADA server on Data Center site.

Actually, this is a common feature as there are a lot of vendors outside there who have capability to do it, especially for manufacture equipment. Cisco they have BSTUN as their proprietary protocol, to transfer Serial data over IP. ESR also has capability to encapsulate Serial data and transfer it over IP connection. It called as ASDP (Asynchronous Serial Device Proxy) and SCADA protocol for specific solution. In this part, I just want to share how to configure ASDP on ESR. As usual, you can refer to the following topology in this scenario.

asdp

 Picture 1: Basic Topology for Serial-over-IP to provide SCADA connectivity

Before we step in further, I suggest you to understand the way of Serial device communicate each other. At this point, I just can tell you there are three operating modes in ESR to establish Serial-over-IP connection with ASDP:

  • Slave mode
  • Master mode
  • Master-Slave mode (Combine)

Please refer to OmniAccess ESR Network Configuration Guide documentation for more detail about those three operating modes. OK, now we’ll see the configuration on each router.

Slave Router:

To check all available interfaces in ESR, you can type the following commands:

Config>list devices

Interface            Connector     Type of interface
ethernet0/0          GE0/FE0/LAN1  GigabitEthernet interface
ethernet0/1          GE1/FE1/LAN2  GigabitEthernet interface
ethernet0/2          SWITCH        GigabitEthernet Switch interface
x25-node             ---           Router->Node
wlan0/0              SLOT4         Wireless LAN Interface
loopback1            ---           Loopback
ethernet0/2.254      ---           Ethernet subinterface
ethernet0/2.253      ---           Ethernet subinterface
ethernet0/2.252      ---           Ethernet subinterface

Usually, Serial interface known as uartX/Y or serialX/Y. If it’s not listed in the router, you can check whether it’s plugged properly or not. Now, you’ll see the configuration in Slave router which is connected to RTU in serial2/0 interface:

set hostname SLAVE
set data-link asdp serial2/0
add device tnip 1

network ethernet0/1
;-This is Physical interface to connect with Provider-
 ip address 192.168.1.2 255.255.255.252
 no shutdown
 exit

network tnip1
;-This is VPN tunnel interface to connect with Master Router in Data Center-
 ip address 10.1.1.2 255.255.255.0
 enable
 mode gre ip
 source 192.168.1.2
 destination 172.16.1.1
 no shutdown
 exit

network serial2/0
;-This is Serial interface to connect with RTU-
 remote-ip 10.1.1.1
 dtr-signal-ignored
 exit

protocol ip
 route 0.0.0.0 0.0.0.0 192.168.1.1
 exit

Master Router:

set hostname MASTER
set data-link asdp uart1/1
add device tnip 1

network ethernet0/1
;-This is Physical interface to connect with Provider-
 ip address 172.16.1.1 255.255.255.252
 no shutdown
 exit

network tnip1
;-This is VPN tunnel interface to connect with Master Router in Data Center-
 ip address 10.1.1.1 255.255.255.0
 enable
 mode gre ip
 source 172.16.1.1
 destination 192.168.1.2
 no shutdown
 exit

network uart1/1
;-This is Serial interface to connect with SCADA server-
 mode master
 remote-ip 10.1.1.2
 dtr-signal-ignored 
 exit

protocol ip
 route 0.0.0.0 0.0.0.0 172.16.1.2
 exit

Make sure those routers can reach each other! Once connection established, the RTU can communicate and send the data to SCADA server through ESR. If the traffic can pass successfully, you’ll see the following status in monitor mode:

serial_status

connection_established

Those pictures show you the statistic and status of serial interface on both side.

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