SNAP2411
INTRODUCTION
The SNAP2411 from Cirronet Incorporated provides Ethernet connectivity to networks of
WIT2411 serial radios. Built around the WIT2411, the SNAP2411 provides a 10/100BaseT
connection to Ethernet networks and functions as base stations for remote devices containing
WIT2411 transceivers. The SNAP2411 allows non-Ethernet serial devices to appear as Ethernet
devices to network-based applications.
Each SNAP2411 can support 60 simultaneous remotes. Each remote radio has a unique ID
number, so the number of remotes that can communicate with a SNAP is unlimited, subject to a
limit of 60 remotes at any one time.
The communication between the SNAP and the WIT2411 remotes is performed using the
WIT2411 over-the-air protocol. Thus the SNAP products are 802.3 compatible but not 802.11b
compatible. By using the 1.23Mbps over-the-air data rate and the WIT2411 protocol, the full
range of WIT2411 radios is realized, three times the range of most 802.11b products.
The SNAPs enjoy the same benefits of frequency-hopping spread spectrum technology that the
WIT2411s do. Namely, the immunity to multipath fading and resistance to jamming that is
provided by changing frequency every few milliseconds. Operating in the 2.4GHz ISM band,
SNAPs can be used license-free.
The SNAP has three modes of operation, TCP/IP, UDP and PPP. The default mode is the TCP/IP
mode. In TCP/IP mode, the SNAP acts like any other network access point as either a client or
server device. This allows standard WinSocket
®
routines to be utilized. Remote devices are
setup to be identified by either an IP address or by a port number under the IP address of the
SNAP. The remote devices send and receive unformatted data to and from the SNAP which
performs the encapsulation and de-encapsulation of the unformatted data into and out of Ethernet
datagrams.
The UDP mode is similar to the TCP/IP mode with remotes operating as clients. This mode
supports the connection-less UDP protocol.
The PPP mode is intended for applications where the remote device is equipped with a PPP
client. In these applications, the SNAP functions as a PPP host providing Internet Access to the
remote devices.
©
2000- 2004 Cirronet
™
Inc
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