DSL Backup Solutions

Overview

The very first and probably most important task in formulating a backup plan is to perform an honest risk assessment of access needs. Although most DSL customers do realize limitations, they elect to implement solutions based on financial considerations. Those customers electing to implement a more sophisticated solution without investing in the one time and ongoing costs of a leased solution, need to evaluate backup plans.

An important facet of planning is technical support. We find that customers with strong internal IT staff or experienced outsourced support have few serious problems that impact their business. On the other hand, those customers that have not planned for the service and support of their LANs and Internet applications tend to experience serious business related problems when outages occur.

RECOL supports the services required to implement Internet access and applications and also acts as the customer's advocate with SNET/SBC. While, a DSL outage occurs, however, the customer needs to have a plan in place to provide those critical services such as Email. It must be well documented and non-technical staff trained on implementing the solution so that when problems occur, backup kicks in as quickly as possible, even if primary support staff are not available.

Backups

The competent design of a backup system is influenced by the applications being supported by your business DSL connection. The following table lists various needs:

Classification	Applications	Example Backup Solution	Caveats
Standalone DSL Backup	Web Browsing, Email on remote server	Dial-up modem or ISDN TA on Stand Alone PC(s) shared by users. Web based Mail.	Users must share PCs
Server Backup	Internal Email	Server Attached modem or ISDN TA.	Technician may need to reconfigure server and systems.
Stand Alone Dial-up/ISDN Router Backup	All supported by DSL	Analog/ISDN Routers from several vendors	Configurations such as gateways need to be changed. ISP may need to implement DNS changes.
Integrated Router Backup	All supported by DSL	Nexland, Cisco and other vendors	May require purchase of new router.

Stand Alone Backup

This solution is based on the customer having one or more modem or ISDN supported PCs available for access to the Internet. RECOL provides a free of charge dial-up account that can be used for access during DSL outages. Customers using RECOL email services can use Web based mail to pick up and send emails. This eliminates the complexity of configuring email clients such Microsoft Outlook Express or Netscape Messaging for each user on backup machines. Although this is a low cost and simple solution, it does require planning and the availability of phone lines that support dial-up modems or ISDN TAs.

Server Backup

Most server operating systems support dial-up modems. On Windows NT and 2000 the services needing to be setup are Dial-Up Networking (DUN) and Remote Access Services (RAS). If users need to use the server for Internet access, then Internet sharing needs to be implemented. This may accomplished with special software such as Microsoft's Proxy server or third party products. A primary use of server dial-up is supporting internal mail servers. For example, NT can be configured to pick up and deliver email when DSL is down via dial-up services. Below is more information on IP services provided by RECOL to automate backup support for customer email servers.

Stand Alone Dial-up/ISDN Router Backup

Supplementing a DSL router with a Stand Alone dial-up or ISDN router can help minimize down time. In this scenario, a separate router is setup and available to take over when DSL goes down. In most scenarios, technicians and/or users would have to make changes to their system configurations so that traffic will be directed towards the backup router instead of the primary DSL router. We have designed and tested simple batch scripts than can assist users in making this change via a desktop icon. We can provide samples upon request. Servers are more complicated and thus may require a technician's expertise to implement changes.

Integrated Router Backup

This scenario seems the best. To date, the new Nexland ISB PRO series routers with integrated serial port seem the simplest and most cost effective solution. Once setup with both DSL and Dial-up/ISDN configurations and attached to a dial-up or ISDN, the ISB Pro will automatically connect via the dial-up or ISDN when it senses that DSL is down. In testing, we have found that it takes about 1 minute for the process to complete. When the router senses that DSL is available, it automatically connects back via the higher speed link. Although we have not tested alternatives, other firms such as Cisco and Netopia offer Integrated Router Backup but they tend to be pricie when compared to the Nexland solution.

Static and Routed IP Considerations

RECOL supports backup via its toll free Dial-Up and ISDN products. The design of the customers public IP Addressing determines the complexity and costs of the backup system.

In the simplest scenarios where the customer connects via one public IP address and has no internal mail servers, all backup plans can be effective. RECOL does not need to implement and manage any special configurations or routing.

RECOL has designed and tested a mail server backup solution using Unix mail relay servers and custom DNS configurations. DNS is setup to direct traffic to one of the following destinations based on availability:

1. The Internal Mail Server via DSL
2. The Internal Mail Server via Dial-Up
3. RECOL mail relay/backup host

Many customers have implemented Internet accessible servers such as Web, Citrix/Windows Terminal Servers and VPNs. These scenario's required special routing and management services but are doable. Please call to discuss custom scenarios as they are outside the scope of this document.

Planning

Sample Network Diagrams

The diagram below shows a typical ADSL setup. Its purpose is to highlight points of failure such as phone lines between the customer site and the SNET Central office. Although managed via RECOL, various entities at SNET, SBC and the customer need to be co-ordinated to troubleshoot and resolve problems.

Summary 

Many customers are successfully utilizing DSL technologies to support their email and other Internet applications. The technology, however, is prone to multi-day outages. A backup plan needs to be implemented to cover critical needs when outages occur. Via its statewide, local phone call dial-up and ISDN network, RECOL offers several services to fit customers backup needs and budget.