Information About Raw Socket Transport
Raw Socket Transport transports streams of characters from one serial interface to another over an IP network for utility applications.
This document describes Raw Socket Transport for the IR1101 and provides a reference section describing the Raw Socket Transport commands.
Raw Socket is a method for transporting serial data through an IP network. The feature can be used to transport Supervisory Control and Data Acquisition (SCADA) data from Remote Terminal Units (RTUs). This method is an alternative to the Block Serial Tunnel (BSTUN) protocol.
Raw Socket Transport supports TCP or UDP as the transport protocol. An interface can be configured to use either protocol but not both at the same time. TCP transport is suitable for applications such as control applications that require acknowledged and sequenced delivery of data. For latency-sensitive applications such as line SEL relays, UDP transport provides faster transport of serial data than TCP.
Raw Socket Transport supports the following for the asynchronous serial interface:
TCP as the transport protocol, with built-in auto TCP connection retry mechanism.
Up to 32 TCP sessions.
Interface configuration as a server, client, or a combination of both.
One server interface, but multiple clients.
VRF-awareness, which enables the router to send Raw Socket Transport traffic to a server host connected through a Virtual Private Network (VPN) Virtual Routing and Forwarding (VRF) interface.
This section includes the following topics:
TCP Raw Socket transport uses a client-server model. At most one server and multiple clients can be configured on a single asynchronous serial line. In client mode, the IR1101 can initiate up to 32 TCP sessions to Raw Socket servers, which can be other IR1101 routers or third-party devices.
The following figure shows a sample Raw Socket TCP configuration. In this example, serial data is transferred between RTUs and a utility management system across an IP network that includes several IR1101 routers. One IR1101 router (Router 1) acts as a Raw Socket server, listening for TCP connection requests from the other IR1101 routers (Router 2 and Router 3), which are configured as Raw Socket clients.
A Raw Socket client receives streams of serial data from the RTUs and accumulates this data in its buffer, then places the data into packets, based on user-specified packetization criteria. The Raw Socket client initiates a TCP connection with the Raw Socket server and sends the packetized data across the IP network to the Raw Socket server, which retrieves the serial data from the packets and sends it to the serial interface, and on to the utility management system.
When you configure the serial link interface on the router as a server, the interface’s peer is the serial link interface on the client router and vice versa.
UDP transport uses a peer-to-peer model. Multiple UDP connections can be configured on an asynchronous serial line.
The following figure shows a sample Raw Socket UDP configuration. In this example, serial data is transferred between RTUs and a utility management system across an IP network that includes two routers (Router 1 which is an IR1101 and Router 2 which is an IR807) that are configured as Raw Socket UDP peers.
In this example, the Raw Socket UDP peer receives streams of serial data from the RTUs and accumulates this data in its buffer, then places the data into packets, based on user-specified packetization criteria. The Raw Socket UDP peer sends the packetized data across the IP network to the Raw Socket peer at the other end, which retrieves the serial data from the packets and sends it to the serial interface, and on to the utility management system.
Serial Data Processing
When the default serial protocol, Asynchronous Communication Protocol, is used, the streams of serial data received by a Raw Socket peer can be packetized based on the following criteria:
Packet length –You can specify a packet length that triggers the IR1101 to transmit the serial data to the peer. Once the IR1101 collects this much data in its buffer, it packetizes the accumulated data and forwards it to the Raw Socket peer.
Packet-timer value –The packet timer specifies the amount of time the IR1101 waits to receive the next character in a stream. If a character is not received by the time the packet timer expires, the data the IR1101 has accumulated in its buffer is packetized and forwarded to the Raw Socket peer.
Special character –You can specify a character that will trigger the IR1101 to packetize the data accumulated in its buffer and send it to the Raw Socket peer. When the special character (for example, a CR/LF) is received, the IR1101 packetizes the accumulated data and sends it to the Raw Socket peer.
See the “Configuring Common Raw Socket Line Options” procedure on page 6 for information about configuring the processing options.
VRF-Aware Raw Socket
The VRF-aware Raw Socket Transport feature enables you to isolate Raw Socket traffic using a VRF for efficient management and control of serial data. After configuring a VRF, you can associate the serial interface configured for Raw Socket Transport with the VRF. See the Raw Socket VRF for a configuration example.