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January 2001 Issue

Managing the Connections
The Road to Open Access - Part 2
By

Offering open access is not just a matter of opening up one’s Internet service to two or more Internet service providers (ISPs). It’s a system designed from the ground up that provides broadband customers with a choice. We continue our series this month with a discussion of connectivity management.

Connectivity management provides the foundation for open access. It is the underlying networking and provisioning scheme that gives multiple ISPs access to all broadband customers. By providing ISPs with access to broadband customers, connectivity management allows these ISPs to configure broadband customers with information specific to their Internet service. This information is unique to each ISP and can differentiate one from another in terms of speed, availability and capability. As a result, each ISP must be able to provide broadband customers with their own Internet protocol (IP) addresses, domain name servers (DNSs), e-mail servers, and so on—connectivity management makes all this possible.

Connectivity management also is responsible for providing broadband customers with much needed transparency among ISPs. Transparency minimizes, or eliminates, the need for broadband customers to perform additional configuration upon changing their current ISP. This allows a broadband customer to change ISPs without needing to reconfigure various Internet applications running on their customer premise equipment (CPE).

To achieve management over connectivity, several things must be considered.

The first is opening access to the hybrid fiber/coax (HFC) network. This enables ISPs to reach out to broadband customers and make them part of their service. Secondly, the broadband customer must be given information to access various components of their service, such as DNS, e-mail and news. Lastly, it must be convenient for the broadband customer to change ISPs. Like changing long distance phone companies, changing ISPs must be completely transparent to the user.

Opening access to HFC

There are several ways open access may facilitate multiple ISPs to access broadband’s HFC networks. One way would be to create multiple radio frequency (RF) local area networks (LANs) off each HFC node.

An RF LAN consists of a network created as a result of a cable modem termination system (CMTS) using a pair of frequencies (one for transmision and one for receiving) on the network. The RF LAN provides an environment that allows one or more cable modems along an HFC segment to use the frequency pair to form a LAN. However, because this is not a traditional LAN connected via fiber or Category-5 wire, but rather by HFC (more specifically two frequencies within the HFC network), it is being referred to as an RF LAN.

In a multiple RF LAN HFC network, there would be two or more independent RF LANs, each using its own unique frequency pair (two RF LANs would require four HFC frequencies). This method would be resource intensive, as it would require separate CMTS gear, or blades, for each ISP, as well as require additional frequency pairs for each ISP on the network. Because headend, rack and frequency spectrum space are all extremely tight, this method of facilitating open access has not received much attention.

However, from purely an operations standpoint, it is the cleanest way of providing total separation among open access choices. This separation results because once the broadband customers select which ISP they want, their cable modems may be provisioned to join that ISP’s designated RF LAN. This action pulls anything behind the cable modem along with it (the CPE is forced to join the cable modem’s RF LAN). Once on the new RF LAN, the traffic, provisioning, and so on, among ISPs are totally isolated from one another on the most critical portion of the transport—the HFC network. This prevents traffic from one ISP from impacting other ISPs.

Another way to provide multiple ISP access to broadband’s HFC is to give each ISP a network presence on each RF LAN. Network presence permits CPEs to obtain IP addresses from their selected ISP. This method uses a single RF LAN that has been populated with a network presence associated with each ISP. Upon activation, the CPE will select which ISP it wants and be provisioned with an IP address from that ISP.

The provisioned IP address will be one from a pool of addresses the ISP has allocated to that RF LAN. Essentially, each ISP will provision a small pool of their IP addresses to each and every RF LAN. These pools of addresses provide each ISP with a network presence on the RF LAN. When that ISP is selected by a CPE, it will be provisioned to that ISP and receive an IP address from that ISP’s address pool wherever it plugs into the HFC network.

This method is the easiest to implement, but suffers from various operational challenges as it grows or is deployed in very large cable systems. For example, all ISPs share the same RF LAN, meaning that traffic from one ISP may affect that of another ISP. There also are challenges with regard to managing IP address space across ISPs. Efforts to manage IP addresses must ensure that when a new broadband customer selects an ISP, an IP address will be available from that ISP on the broadband customer’s RF LAN. As a result, each ISP would need to continually balance its need to conserve IP addresses with its need to provide opportunities for new broadband customers to join their service.

Configuring CPE for applications

Once a CPE has been provisioned with an IP address from the broadband customer’s desired ISP, it then becomes ready to be configured for that ISP’s applications, which include e-mail, news, DNS and Web hosting. These configurations may be applied manually or automatically depending on the ISP and the application. For example, DNS may be configured automatically alongside the IP address during provisioning, whereas the news server must be manually configured. These configurations also may take on two different forms: IP address or hostname. An IP address configuration merely consists of an IP address, such as 24.128.44.6. A hostname configuration, such as news.mn.mediaone.net, consists of a pointer to an IP address.

While both of these configurations potentially could have the same result, they are vastly different operationally. For example, using a hostname instead of an IP address is easier to maintain, because this information may remain constant even if the IP address pointed to it changes. However, an IP address must remain constant because a change in this information would require all CPEs with this information to be changed—a major undertaking if the information is configured manually.

Once configuration has been completed, the broadband customer is fully operational—at least until he changes his mind and would like to switch ISPs. When this occurs, he must re-establish connectivity with the new ISP and configure its CPE applications to work with the new ISP. The inconvenience this creates for the broadband customer alone will reduce the frequency of ISP changes. Thus, there must be transparency among ISPs.

Making ISPs transparent

Although all ISPs are different, they provide many of the same things—Internet access along with similar applications that use the Internet, such as e-mail, news and Web hosting. These similar applications allow standards-based application clients to run on the broadband customer’s CPE. Even though ISPs may run different vendor applications because these applications are standards-based, broadband customers merely need to configure their CPE to use them. While some CPE vendors have made the task of changing configurations easy by providing a single interface for changing common Internet configurations, it is still necessary for broadband customers to manually configure their CPE after changing ISPs.

Another problem with manual configuration changes is that it complicates open access evolving from a choice of ISPs for all services to an à la carte offering. An à la carte offering would permit a mixture of ISP services as well as third-party service providers to be bundled together to produce a complete Internet service for the broadband customer. However, this bundling may be confusing to the broadband customer because nearly any type of change would require additional manual configuration of the CPE by the broadband customer.

Changing ISPs also may impact certain externally important contact information about the broadband customer. For example, if broadband customers change the ISP providing their e-mail, their e-mail address would change. This can be damaging because everyone the customers previously shared their e-mail addresses with would now have the wrong information. Similarly, a broadband customer’s personal Web or voice-over-IP (VoIP) service site also may be impacted by the change of the ISP that provides this service.

By providing transparency, the broadband operators look out for the best interest of their customers. Transparency supplies the broadband customer with an address for e-mail, Web hosting and VoIP that does not change regardless of which ISP or third-party service provider actually offers the service. It also extends the broadband operator an opportunity to brand the service in its company name as opposed to the broadband customer’s current ISP selection. As a result, all customers will have personal Web pages and e-mail addresses with the broadband operator’s name, which will not change, no matter which ISP handles this functionality for the customer.

Connectivity management must offer inviting opportunities to attract service providers who are new to broadband. These service providers may then compete with existing ISPs and service providers for broadband customers. Connectivity management must also make joining existing service providers and ISPs simple and painless. Lastly, connectivity management must emphasize transparency for broadband customers so when they make changes, the only thing they need to change is the amount of money they save each month for the service.

Bruce Bahlmann is director of technical market development for Alopa Networks. He may be reached via e-mail at .

Figure 1: Multiple RF LAN w/ Single ISP Network Presence

Figure 2: Single RF LAN w/ Multiple ISP Network Presence

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