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GadgetGateway Overview
2.1 Introduction
Chapter 2: GadgetGateway Overview
2.1 Introduction
The GadgetGateway router forwards packets that use the ANSI/EIA 852 and ANSI 709.1
protocols between an 852 based Internet Protocol (IP) channel (using Ethernet) and a
TM
ANSI/EIA 709.1 (LonTalk
) channel (using TPFT-10 or TPXF-1250 transceivers). The
GadgetGateway has a presence, or physical connection, to both networks. The Gateway
takes ANSI/EIA 709.1 messages from the ANSI/EIA 709.1 network and transports them
through the IP network wrapped in an ANSI/EIA 852 packet. The ANSI/EIA 709.1 pack-
ets, or messages, cannot travel over IP by themselves, so an alternate means of transport is
necessary. ANSI/EIA 852 acts as the transport service to convey ANSI/EIA 709.1 mes-
sages over IP networks to other 709.1 to IP routers or devices. The messages are then
unwrapped back into native ANSI/EIA 709.1 messages and sent on their way. The 852
protocol is a generic tunneling protocol and is not limited to ANSI 709.1 (LonTalk). In
852 parlance the tunneled protocol is a Component Network or CN protocol. In some of
the figures CN or CN/IP is used to represent a Component Network or Component Net-
work to IP connection or network.
This technique of using another protocol (i.e., ANSI/EIA 852) to transport a message over
an alternate media is often referred to as "tunneling." ANSI/EIA 852 not only provides the
vehicle to transport ANSI/EIA 709.1 messages across IP, but it also provides management
of these connections or routes. The ANSI/EIA 709.1 messages have no information or
awareness of the tunneling process, so when a message arrives at a 709.1 to 852/IP router,
an independent management process from ANSI/EIA 852 must determine whether and
where to deliver the ANSI/EIA 709.1 messages.
Both the ANSI/EIA 709.1 and ANSI/EIA 852 are open standard protocols defined as part
of a committee hosted by the Consumer Electronics Association. For more details see
ce.org.
Network connection devices can operate at different layers of particular networks protocol
stack. ANSI 709.1 is an OSI 7 Layer type protocol. Whereas the internet protocol has only
4 layers. See Figure Figure 2.1 for a diagram of the different layers of the two protocols. A
network connector is a device that joins different parts of a network. Connectors have a
specific name that is dependent on the layer at which the connector operates. For example
a router operates at the network layer and a gateway at the application layer. Because
higher layers of the protocol do not have access to some of the information stripped away
by lower layers, network connector s operating at different layers have different capabili-
ties. There is also some abuse of terminology so that the descriptions of network connec-
tors from different manufacturers may be confusing. For example, a repeating router may
be called a repeater for short. Although a repeating router acts similarly to a physical layer
2-2
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