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Business Recovery For Data NetworksSolutions for Private Line & Frame Relay Data networking needs have been rapidly expanding as a result of new applications and higher bandwidth requirements. Today’s data networks no longer use a single technology. Rather, they are hybrids using technologies that are being driven to the limit with more users and ever-increasing traffic. At the same time, corporations have come to realize that their proprietary information is a most valuable asset, which provides a distinct competitive advantage. As such, it needs to be guarded, yet be readily available to authorized personnel. Industry regulations, court rulings and political unrest also remind us that data must be protected. There are many methods that provide network redundancy and reliability. This article will briefly discuss some of the solutions offered by interchange carriers (IXCs) for private line and frame relay technologies. Private Line Network Management Sophisticated network monitoring and management tools have been available for many years. However, they are now gaining wider acceptance for several reasons: 1. Users have become more comfortable in taking responsibility and accountability for their networks. 2. Businesses—large and small—are now realizing that internetworking products can reduce downtime and thus could pay for themselves in six to nine months. 3. Network management tools give users on-premises control and monitoring capabilities. Monitoring and Management Tools What to Look for… Users can configure their physical circuits into logical channel groups and monitor and dynamically manage these channel groups from the DS0 through DS1 bandwidth levels. A further benefit is access to a shared network facility pool for additional part-time bandwidth. Look for… • Restoration on customer-owned
spare bandwidth Look for… Ask the question: "To what am I subscribing?" Network Management – "Hand-off" or "Hands-on"? Customer Managed Network Customer managed networks utilize a PC or workstation with their IXC’s proprietary software to allow dynamic reconfiguration and control of permanent dedicated bandwidth. Connection to the IXC’s system controller and switching devices is with a dedicated 9.6Kbps or 56Kbps private line access channel. A dial-up access line is also available for those with virtually static networks that still want the comfort of knowing they could make their own changes. The PC is used to communicate with the carrier’s system controller, which verifies security information. The system controller in turn communicates with Digital Access Connect Switching (DACS) devices deployed at the IXC’s central offices. These switches receive their cross connect information from the system controller and perform the requested network cross connects using either user owned bandwidth, or IXC owned bandwidth from the B-o-D pool to make the necessary connections. Vendor Managed Network •
Have a virtually static network B-o-D is a shared pool of IXC facilities used for temporary peaking or disaster recovery needs. B-o-D is a very cost effective alternative to purchasing permanent dedicated facilities in many instances. Here are a few examples of B-o-D uses: •
A large merchandise retailer sends receipts to its
data center for processing once a month A Word of Caution… Recovery from Failures In the event of a major geographic incident, the user’s primary data center and the IXC carrier office can be affected. However, the user is able to recover in minutes by individually mapping traffic from each remote city to the secondary location using the GUI of their network management software. Although slightly more expensive than the previous configuration, it demonstrates the robustness and flexibility of these IXC features since none of the remote cities are isolated from the secondary data center. Frame Relay Service Recovery There has been limited introduction of frame relay disaster recovery across the IXCs. Those IXCs offering these features are enabling users to complete the reliability picture beyond the inherent frame relay backbone features. Disaster recovery planning should incorporate scenarios that are created by the customer, IXC carrier sales team, and the IXC technical group with input from a disaster recovery vendor as appropriate. These options cover a number of different recovery situations. Your specific needs and requirements will determine which options are best for your network. This is an effective approach if the recovery scenarios are kept current. General Features Overview 1. Access protection features allow Permanent Virtual Circuits (PVCs) connected to a failed access circuit to be moved to an alternate access circuit within minutes of a customer declared failure. 2. Backup Permanent Virtual Circuits (BPVCs) allow traffic to be routed from a primary to a secondary location. 3. Growable Permanent Virtual Circuits (GPVCs) not only redirect traffic to a secondary location but increase the bandwidth requirements to meet your application requirements as well. Use of hybrid arrangements of private line and frame relay features allows users to reroute frame relay traffic to other locations, such as a hotsite. The restoration objective for each of these features is less than or equal to 3 minutes per PVC moved. Total time frames to execute transfers from primary to secondary data sites will depend on the number of PVCs in the disaster recovery scenarios. You may activate multiple disaster recovery scenarios simultaneously to reduce the total timeframe. Re-routing of the PVCs is achieved through use of a specialized disaster recovery software tool in the IXC's frame relay Network Operating Center (NOC). Furthermore, using a specially designed tool, the IXC's network capacity engineers manage and monitor network capacity for customer configurations so that network capacity is always available. Additionally, you should prioritize which PVCs are to be moved first by pre-defining subsets of PVCs to be transferred to the secondary port. By doing this you can minimize the transfer time of the high priority PVCs that need to be operational more quickly. Therefore, it is recommended that your entire plan be divided into subsets of 20 PVCs or less. Three Recovery Options Backup Permanent Virtual Circuits BPVCs are targeted at customer networks with key locations such as large primary data centers or locations with mission critical applications. Users can activate or deactivate BPVC scenarios with a phone call to the IXC's frame relay NOC. You must initiate this activity and call to have the PVCs returned to their normal configuration condition. Please note that only one primary path is active! BPVCs use the same DLCI/IP address at the secondary or backup location as the primary PVCs. This is to enable the redirection of many remote users from the primary data center route to the secondary data center route in a virtually transparent mode. Hence there is no need to revise routers at the customer’s remote locations. Growable Permanent Virtual Circuits Once GPVCs are implemented, a customer can call the IXC NOC to activate and deactivate the GPVC scenarios. During activation of GPVCs, the primary PVCs are deactivated and the CIRs of the GPVCs are increased to the CIR of its corresponding primary PVC. Note that two paths are initially active, hence DLCI/IP addresses of the primary and secondary ports are indeed unique. GPVCs are not as popular as BPVCs since remote router table revisions could be required to reflect redirection of PVCs from the primary to the secondary locations. Which Technology or Approach is Better for Me? There are no hard and fast rules. Your decision will vary based on the criteria and assumptions you use. This author suggests the following items should be included in your comparison and decision criteria: •
Ease of set up The reason for designing a reliable and secure network is to insure your business is available to your internal and external customers when and where it is needed. The cost of reliability versus the cost of downtime must be weighed against one another. Do an in-depth analysis and create a comparison scorecard to help you decide how much and which features you should pursue. There are a number of options available for ‘hands-on’ and ‘hands-off’ users. Whichever recovery technology or approach you select, test aggressively and often!! About the Author |