2.1 Overview

The ENUM Support feature introduces ability in vSTP or DSR to handle DNS or ENUM queries using the UDR to store ENUM database. A new vENUM MP is introduced running ENUM application and using bind9 software to support DNS interface over UDP.

This feature introduces a new MP type (C-level server) as vENUM MP, that processes DNS or ENUM messages from external DNS clients. vENUM application running in the vENUM MP uses bind9 for interacting with the external Domain Name System (DNS) clients. vENUM MP makes UDP connections with external querying clients and receive DNS queries.

For ENUM queries, the ENUM application queries the UDR for DN received in the message. After receiving response from UDR, ENUM application generates the DNS response and sends it to the client through bind9 process.

ENUM Architecture with DSR

The following figure shows the overall system architecture for the ENUM feature with DSR:

Figure 2-1 ENUM Architecture with DSR

Architecture for vENUM

Figure 2-2 Architecture for vENUM

E.164 Number Mapping (ENUM)

E.164 Number Mapping (ENUM) is a Telephone Number Mapping standard defined for mapping traditional PSTN numbers in E.164 format to IP-based format such as URI. ENUM uses a special DNS record type to translate a telephone number into a URI that can be used in an IP network. ENUM allows Internet-based services, such as e-mail, VoIP, and Voice Mail, to be located based on the telephone number. ENUM accomplishes this by placing the telephone numbers into the global Domain Name System (DNS).

The following figure shows an example of the ENUM Tier resolution from a DNS perspective. The ENUM data format begins with a phone number, then reverses the digits, places a “.” between each number, and adds the .e164.arpa root domain that is common across both ENUM and this feature.

Figure 2-3 ENUM Tier Record Resolution

ENUM implementation is based on a tiered architecture. At Tier 0 is the RIPE NCC which maintains the e164.arpa zone. Entries in the RIPE NCC DNS server correspond to country codes or portions of country codes and point to the Tier 1 Registry, the authoritative DNS server for that country code or portion of country code. The Tier 1 Registry maintains records that indicate the authoritative DNS server for individual E.164 numbers in the country code or portion thereof. The Tier 2 Provider for an E.164 number maintains the actual NAPTR records that contain information for specific communication services.