RFC 1645 (rfc1645) - Page 2 of 18
Simple Network Paging Protocol - Version 2
Alternative Format: Original Text Document
RFC 1645 SNPP - Version 2 July 1994
some paging terminal, somewhere. In most cases, this delivery is
made using TAP (Telocator Alphanumeric input Protocol, also known as
IXO). This protocol can be a somewhat convoluted, and complicated
protocol using older style ASCII control characters and a non-
standard checksumming routine to assist in validating the data.
Even though TAP is widely used throughout the industry, there are
plans on the table to move to a more flexible "standard" protocol
referred to as TME (Telocator Message Entry Protocol). The level two
enhancements to SNPP (as described below) are intended for use with
this forthcoming standard.
However, acknowledging the complexity and flexibility of the current
protocols (or the lack thereof), the final user function is quite
simple: to deliver a page from point-of-origin to someone's beeper.
That is the simple, real-time function that the base protocol
attempts to address. Validation of the paging information is left
completely up to the paging terminal, making an SNPP gateway a direct
"shim" between a paging terminal and the Internet.
3. Why not just use Email and SMTP?
Email, while quite reliable, is not always timely. A good example of
this is deferred messaging when a gateway is down. Suppose Mary Ghoti
() sends a message to Zaphod Beeblebrox's beeper
(). Hugecompany's gateway to the
Internet is down causing Mary's message to be deferred. Mary,
however, is not notified of this delay because her message has not
actually failed to reach its destination. Three hours later, the
link is restored, and (as soon as sendmail wakes up) the message is
sent. Obviously, if Mary's page concerned a meeting that was
supposed to happen 2 hours ago, there will be some minor
administrative details to work out between Mary and Zaphod!
On the other hand, if Mary had used her SNPP client (or simply
telnetted to the SNPP gateway), she would have immediately discovered
the network problem. She would have decided to invoke plan "B" and
call Zaphod's pager on the telephone, ringing him that way.
The obvious difference here is not page delivery, but the immediate
notification of a problem that affects your message. Standard email
and SMTP, while quite reliable in most cases, cannot be positively
guaranteed between all nodes at all times, making it less desirable
for emergency or urgent paging. This inability to guarantee delivery
could, whether rightly or wrongly, place the service provider in an
uncomfortable position with a client who has just received his or her
emergency page, six hours too late.
Gwinn