Teldat REGESTA 1, Руководство по установке и настройке

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SLIP is the predecessor of the more commonly used and extended PPP (Point-to-Point Protocol). However, with mi-
cro-controllers, SLIP encapsulation for IP packets continues to be used as it has a very small overhead.
SLIP needs its IP address to be configured before being established.
So that SLIP runs correctly, its serial port configuration needs to be 8 data bits with no parity. One version of SLIP
with header compression is CSLIP (Compressed SLIP). This was developed by
Van Jacobson and its role was to re-
duce the typical 40 byte header to 3 or 5 bytes helped by the fact that many of the header fields do not vary during a
connection.
SLIP modifies each IP datagram adding a special character C0 or “SLIP END” so it can differentiate between differ-
ent datagrams. To prevent line noise it usually sends one at the beginning as well and consequently assumes that
any previous erroneous connection has terminated.
If the C0 character is present in the datagram content, it uses the two byte sequence DB, DC. The DB character is
the SLIP escape character. If the escape character is presented within the content, it is replaced by the DB, DD se-
quence.
Fig. 7:
SLIP Protocol
In the REGESTA 1 router, SLIP is configured so that the protocol knows, beforehand, the local IP address and the IP
address of its remote pair. I.e. there is no dynamic addressing so the two connected devices must know their re-
spective IP addresses. Both addresses must pertain to the same network.
You must also program the type of SLIP to use. It’s very important that both devices are configured with the same
mode (slip, cslip, slip6, cslip6).
The mode which the REGESTA 1 router uses to route the IP datagrams, which come through the GPRS interface, is
based on the creation of visible ports. This routing mode DNAT (Destination-NAT) is valid to create the visible port.
When the device is configured in SLIP mode, all IP datagrams with source in the GPRS network and that have the
port configured in visible port as destination TCP port, are sent through the SLIP serial port to the remote terminal.
All the IP datagrams with source in the remote terminal, which are sent through the SLIP serial port, are sent to the
GPRS network.
1.3 SCADA characteristics
The features supported by the SCADA Interface are as follows:
- Type of serial Interface supported:
RS-232 (presents DCE configuration)
- Protocols over asynchronous serial line:
Teldat S.A.
1 Description
REGESTA 1 5