SS7 NETWORK ARCHITECTURE
The SS7 network architecture has four major protocols:
- A7 - American National Standards Institute (ANSI)
- C7 - Consultative Committee on International Telegraphy & Telephony (CCITT) / International Telecommunications Union (ITU)
- CH7 - Chinese variant (derived from C7)
- J7 - Japanese variant (derived from C7)
The A7 protocol is used throughout North America and Canada. The C7, CH7, and J7 protocols are similar in design. The C7 variant is used in Europe and other eastern countries, Latin America, and the Asian/Pacific region; CH7 is used in China, and J7 in Japan.
C7 Networks
The below diagram is a basic illustration of a C7 network. Equipment and link redundancy are required in the A7 variant of SS7 networks. For a C7 network, redundancy is not necessarily a requirement, but it can be engineered to be redundant. If redundancy is deemed necessary, an SSP could perform the functionality of an STP, and vice versa. SCPs, however, are segregated and perform only that function.
A7 Networks
The most important requirement for an A7 network is redundancy in both equipment and links. This ensures that the network, when coupled with automatic error recovery capabilities, will be highly reliable. A signal will reach its destination to complete a call or a service the majority of the time.
Redundancy Provides Alternative Routes
Because of the use of STPs, the A7 network architecture enables signaling to occur between networks and network end points (i.e., SSPs and SCPs), which would otherwise have no direct connection. For example, if a cellular phone on a wireless network must make an 800 call to a wire-based phone, it can do so by accessing an SSP (and the SCP needed to do the local number translation) in an SS7 network.
<< Back Continue to SS7 Stack >>