2.1 SMS/800 Service Overview
SMS/800 currently supports the X.25 Protocol. This Protocol will continue to be supported until all SCP O/O migrate to the TCP/IP Interface. During this transition period an SCP can use the X.25 Interface until they cut-over to the TCP/IP Interface.
2.2 TCP/IP versus X.25
The decision to migrate from X.25 to TCP/IP is based on a combination of limitations with the X.25 protocol and strengths of the TCP/IP protocol:
- is old (early 1980s), was designed for low speed unreliable transmission media (no guarantee of delivery)
- cannot share bandwidth (requires dedicated physical link to Packet Switched Data Network or peer)
- incurs high production cost because of the need for dedicated modems, wiring, ports for each link, etc.
- incurs high maintenance cost for a complicated operations environment with many modems, wires, ports, etc.
- supports only point-to-point connections, which makes machine and link relocation difficult
- incurs high machine overhead cost
- support from vendors is decreasing as new applications are no longer using this protocol.
- is the industry standard (DoD RFC 793), and it was designed for high speed transmission
- incurs lower production cost because no dedicated hardware is required for new TCP connections
- incurs lower maintenance cost (less dedicated hardware is needed)
- permits easier machine relocation
- incurs lower machine overhead
- is a mature internet protocol that is implemented worldwide. The World Wide Web is based on IP network technology.