Author: Diarmuid O'Briain, MSc, MCGI, BSc (hons), GCGI, CEng, FIEI, FIET, is chief technical officer at Ripple Communications Ltd enet launched a fibre direct Open Access Network pilot programme with the aim of delivering Fibre To The Business (FTTB) to Small to Medium Enterprises (SME) in selected Metropolitan Area Network (MAN) towns. As enet holds concessions on 94 MANs across the country the potential to deliver a fibre direct service to enable SMEs is compelling. To trial the concept a pilot consisted of four towns, Claremorris, Loughrea, Ardee and Kilkenny City was initiated. In these towns enet has rolled out a wholesale Open Access Gigabit Passive Optical Network (GPON) network. Ripplecom were selected as the retail carrier for three of these towns, Loughrea, Ardee and Kilkenny City.

Hybrid fibre/wireless solutions

[caption id="attachment_21169" align="alignright" width="300"]ripple-1 Core network development[/caption] Historically Ripplecom has focused on the delivery of network solutions via wireless. However in recent times this has changed with services being offered over other operators' fibre as well as hybrid fibre/wireless solutions to provide resilience. When enet proposed fibre direct it generated significant interest within Ripplecom to operate as a retail provider over these new wholesale networks. enet provides the fibredirect using GPON infrastructure in the pilot towns. This comprises of a centralised GPON Optical Line Terminal (OLT) connected to the MAN. As the fibre reaches the streets Passive Optical Splitters (POS) split each fibre out by up to 32 fibres to individual premises and each split is terminated by an Optical Network Unit (ONU) presents a 1000 Mb/s RJ45 Ethernet interface at the customer side. Logically this interface presents three Virtual LANs (VLAN), one for data, a second over which a prioritised voice service is delivered and a third for management. The OLT upstream is presented physically to Ripplecom, the service provider at a data centre in Dublin. The decision to incorporate separate VLANs for data, voice and management not only ensures high availability for sensitive traffic but also mitigates any of the security vulnerabilities typically associated with RG management and voice traffic. To provide retail services Ripplecom has built a new core infrastructure to accommodate the fibre direct service. This includes a Dynamic Host Configuration Protocol (DHCP) Subscriber Management server to assign IP address, a Remote Access Dial-in User Service (RADIUS) Server to authenticate customers and an Automatic Configuration Server (ACS) to automatically configure Residential Gateways (RG) using the CPE WAN Management Protocol (CWMP). All of these required integration into the existing Customer Relationship Management (CRM) system.ripple2a

Unique circuit ID

New customers are identified by a unique Circuit-ID linked to each premises. On completion of the fibre install by enet and the subsequent handover to Ripplecom, this Circuit-ID is associated with the customer details in the CRM system. The CRM builds a unique record in the Remote Access Dial-in User Service (RADIUS) Server database and manages this throughout the life of the account.

RG initial boot and IP address retrieval

Customers are supplied with a Retail Gateway (RG) by the installation technician. Upon initial boot this RG makes a DHCP Request on the Broadband VLAN to the DHCP Server on the Ripplecom network. While passing through the enet GPON OLT a DHCP option82 header including the Circuit-ID is inserted in the DHCP Request header. This Circuit-ID identifies the particular premises from where the request came from. The DHCP Server makes a RADIUS Access: Request for this Circuit-ID to the RADIUS Server. As the RADIUS Server was pre-loaded with the customer details, including the Circuit-ID during the provisioning process, it can identify the associated record for the customer and supply the designated IP address back to the DHCP Server as part of the RADIUS Access: Accept message. The DHCP Server responds with this IP address via a DHCP Offer and while passing through the OLT the option82 header is removed before forwarding the offer to the RG.

RG firmware upgrade and auto-configuration

Once the RG has an IP address it requires a firmware upgrade and configuration, for this it sends an CWMP INFORM message to the ACS Server. The ACS Server responds with a connection request which the RG accepts. The ACS Server can then perform a firmware upgrade if necessary. The ACS Server consults the CRM as to which configuration sets are appropriate for the RG and pushes the selected configuration values based on the service the customer has purchased. If the customer has purchased a voice service an additional prioritised VLAN is established via the pushed configuration to the RG. The RG can support multiple traditional Plain Old Telephone Service (POTS) or Integrated Services for Digital Network (ISDN) Basic Rate Access (BRA) lines. To handle voice services the RG registers with the Softswitch using Session Initiation Protocol (SIP). For calls in and out, SIP signalling between the RG and the Softswitch, as well as SS7 signalling between a Signalling Gateway (SG) function in the Softswitch and the Eircom Service Signalling Point (SSP) establishes voice connections over Real Time Protocol (RTP) bearers which are mediated to the Eircom Exchange via a Media Gateway (MG) function thereby providing connectivity to the Public Switched Telephone Network (PSTN).

Summary

Through the fibre direct pilots, Ripplecom Engineering has developed significant expertise in the delivery of high availability and secure services over fibre as well as building new core infrastructure. Sales and customer services have also developed new skills and expertise that broaden the company outlook and will allow Ripplecom to explore new business horizons in the future. See www.engineersjournal.ie/broadband-fibre-network

Abbreviations

ACS Automatic Configuration Server BRA Basic Rate Access CRM Customer Relationship Management CWMP CPE WAN Management Protocol DHCP Dynamic Host Configuration Protocol FTTB Fibre To The Business GPON Gigabit Passive Optical Network IMT Inter-Machine Trunk IP Internet Protocol ISDN Integrated Services for Digital Network LAN Local Area Network MAN Metropolitan Area Network MG Media Gateway OLT Optical Line Terminal ONU Optical Network Unit POS Passive Optical Splitter POTS Plain Old Telephone Service PSTN Public Switched Telephone Network RADIUS Remote Access Dial-in User Service RG Residential Gateway SG Signalling Gateway SME Small/Medium Enterprise SSP Service Switching Point VLAN Virtual Local Area Network