Aug 14, 2006Many people think about RFID in terms of tags, readers and middleware, overlooking the importance of the network infrastructure transporting data through these RFID system components. The result is a widespread misperception that RFID will slow critical business applications by clogging the network with massive amounts of tag data. In fact, basic RFID implementations add minimal data to the network, and you can easily improve performance in larger systems by fine-tuning the network foundation.
A quick solution for complying with an RFID business mandate might include a few preconfigured readers and printers, prepackaged software for label generation and an advance shipment notification (ASN) application that runs on a PC or router module. One Cisco customer fulfilled a compliance mandate for an introductory RFID system with one reader, one printer and some middleware to route and filter traffic at the network edge.
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Like other customers with small RFID implementations, this customer tracked material at the pallet and case level. Without the high volume of data generated by item-level tags, the RFID data added minimal network overhead and other network-dependent applications were not affected. The only network requirement was a single LAN segment with three Ethernet ports—one for the printer, one for the reader and one for the middleware server.
This approach is adequate for basic RFID procedures that are not fundamental to the overall network architecture. To gain value from RFID that transcends mandate compliance, however, you'll need to integrate your RFID system into your enterprise network architecture.
Network Guidelines
If you have identified applications with enough ROI to support a more comprehensive implementation, you'll need to address the basic network considerations of availability, performance and security. By addressing these issues in the network foundation, you can create a solution that delivers RFID data whenever and wherever business requirements dictate, while maintaining enterprise-wide application performance.
Availability planning starts with an architecture that eliminates single points of failure along the network path the RFID data will travel. RFID vendors generally recognize the benefit of RF redundancy at a dock door, and you can extend this concept throughout your network to protect against a wide variety of component failures. Examples of redundancy at the network level include dual data paths and port-level redundancy on network switches.
Once a high-reliability network path for RFID data is in place, the next step is giving RFID data a suitable network priority for the business application. For some basic compliance applications, timely delivery of RFID data does not offer a sufficient ROI to warrant special network consideration. In other applications, RFID data delivery is mission-critical and cannot tolerate delay. For example, a sophisticated RFID solution might be linked with an intelligent routing system that sorts packages as they move down a high-speed conveyor. With the conveyor moving at 600 feet per minute, delays can result in material moving past its intended destination, potentially affecting customer shipments and adding routing time and cost.
In addition to high-speed communications within a facility, you should consider the impact of RFID communication over the lower-speed WAN links connecting remote facilities. Large enterprises such as retail chains often connect stores through a fractional T1/E1 WAN, dial-up connection or other low-bandwidth service because these technologies are far less expensive than high-speed, dedicated links. The performance of these lower-speed connections can degrade under excessive loads.
You can maintain WAN performance in a large, data-intensive RFID implementation by using middleware to aggregate and filter the RFID data within the network edge. Filtering reduces the volume of raw tag-read data transmitted within the site and over the WAN by limiting transmission to essential data. For example, filtering can prevent duplicate tag reads from being sent when a package remains in the same read field for an extended period of time.
Network Optimization
Maximizing RFID application efficiency via network optimization is best accomplished through collaboration between the RFID application and network engineering teams. By working together, the two groups can maximize the value RFID will bring to the enterprise architecture, while preserving the performance of network-dependent resources such as SAN and VoIP.
For example, network administrators can use data-flow analysis to optimize the network for RFID before the system is fully deployed. Data-flow analysis requires knowledge of protocol overheads, network forwarding paths and network QoS capabilities because the tag data is actually a very small portion of the traffic generated by a tag-read event. Many RFID readers use XML over TCP to transmit tag data to the middleware. The TCP protocol uses a three-way handshake to establish a connection between devices before sending data; it uses a similar process for session completion. This handshake adds several packets to the actual tag data. Once the TCP connection is established, the tag data is encapsulated within an XML format that adds even more overhead to what started out as a minimal amount of RFID data.
The data-flow analysis lets the network team simulate reader, middleware and application transactions to understand the potential amount of data generated by the RFID network. Through careful evaluation of each read point type within the RFID network and its interaction with middleware and other enterprise applications, the team can begin to project how much traffic the RFID implementation will introduce, and adjust the network foundation to maximize application performance.
Data-flow analysis is especially important in wireless networks, which typically have less usable bandwidth than wired networks. Manufacturing operations requiring RFID commonly deploy an IT infrastructure over a combined wired and wireless network. Network teams can maximize performance over wireless networks by filtering RFID data, and by using high-performance wireless standards such as 802.11a and 802.11g.
RFID and network teams can also work together to protect the network from attacks that might degrade network performance. Many RFID security issues are not yet well understood, and RFID networks are subject to security concerns at the reader and tag levels. Network-savvy teams can minimize potential threats by taking advantage of policy-based access controls, data authentication, encryption and other security products offered by Cisco and other major networking vendors.
In addition to securing the network against unauthorized access and other common threats, the network team can further protect RFID data by logically segmenting RFID devices on their own virtual network. For mission-critical RFID data, this option is worth a bit of extra management effort to protect the RFID application from external threats such as worms and viruses, as well as any unnecessary data originating on non-RFID devices.
In addition to protecting RFID data from loss or tampering, security mechanisms can also protect the business from threats arising from the misuse of stolen data. For example, RFID data that indicates how many units of a recalled product remain on a store shelf might not be valuable by itself. Placed in a business context, however, a person could purchase such a product and then initiate a lawsuit claiming the product remained on the shelf after a safety recall. Encrypting the tag data as it crosses the network can reduce this type of threat.
A Lifecycle Approach
Like any other technology implementation, RFID is best executed using a "lifecycle services" approach that will help you get the most business value from your technology investment. This approach begins with developing a business case and establishing a high-level conceptual architecture. Do you need an extensive RFID system with full network redundancy, or will a basic implementation on one LAN segment meet your needs?
Next, assess your environment to determine whether it can support the proposed system with adequate performance and security. A data-flow analysis will tell you whether the RFID system will affect other applications, and whether network upgrades are indicated. With the proper preparation and planning, you'll be able to design and implement a solution that meets your business and technical requirements without disrupting the network or creating points of vulnerability.
Once the system is operational, maintain network health through day-to-day operations and optimize the solution by adapting the architecture, operation and performance of the network to evolving business requirements. Addressing all aspects of the solution lifecycle for your people, processes and technology will help you successfully install and operate a secure RFID system—with the performance you need for basic mandate compliance or a large, business-critical implementation.
Michael Crane is the senior director of advanced services for Cisco Systems.
