rpsel

RPSL, or the **Resource Public Switched Landline Network**, is a protocol and data format used primarily in the telecommunication industry to manage and query routing information for the public switched telephone network (PSTN). It was developed by the International Telecommunication Union (ITU) and is standardized under the ITU-T recommendation **Q.1500**, part of the Q series of recommendations for signaling in telecommunication networks.

RPSL is designed to facilitate the exchange of routing information between network operators, particularly for international calls. It allows for the dynamic and efficient distribution of routing data, such as country codes, area codes, and transit network identifiers, which are essential for call routing. The protocol operates over TCP/IP networks, enabling seamless integration with modern internet-based infrastructure.

The data format of RPSL is structured in a hierarchical manner, consisting of records that describe network prefixes, transit points, and associated attributes. These records are used to define how calls should be routed through various network segments, including international gateways and transit providers. Operators can publish their routing information in RPSL files, which are then distributed to other network participants via specialized servers or databases.

RPSL is widely adopted in global telecommunication networks due to its flexibility and scalability. It supports both static and dynamic updates, allowing operators to adjust routing configurations in real-time to accommodate changes in network topology or service offerings. The protocol is also compatible with other ITU-T standards, such as the **ISUP (ISDN User Part)** and **SIGTRAN (Signaling Transport)**, ensuring interoperability across different telecommunication systems.

While RPSL is primarily used for PSTN routing, its principles and mechanisms have influenced other areas of network management, including internet routing protocols like BGP (Border Gateway Protocol). However, it remains distinctively focused on telephony applications, serving as a critical tool for maintaining the reliability and efficiency of global voice communication networks.