Cisco CNS Network Registrar offers IP address management capability that helps you address the complexity of managing a dynamic corporate environment through automation of IP address assignment. As the need to deliver centralized management services rises, including global application delivery, the scalability and high performance of Cisco CNS Network Registrar will make it your choice for rolling out new products and services. In the manufacturing environment where proprietary networking technology still commands the dominant role over Ethernet, Cisco CNS Network Registrar can help you deploy standard Ethernet for lower capital cost and better management capability. Its rich and flexible features allow a device to have the same IP address as the device it replaces without operator intervention.
CHALLENGE
A traditional manufacturing network (Figure 1) consists of:
• The control network that connects controlling and monitoring devices including Programmable Logic Controllers (PLC), I/O racks, and PC-based controllers on the plant floor. Because the control network does not support Ethernet, it requires a gateway device to transmit information from the manufacturing floor to the corporate network.
• The device network using slow but highly reliable proprietary protocols to connect plant floor devices, such as sensors, to automation and motion equipment such as robotics, motor starters, and other devices on the manufacturing lines.
Figure 1. Traditional Manufacturing Network
Today manufacturers depend on proprietary protocols to interconnect devices on the manufacturing floor. These protocols have the following drawbacks:
• High installation and maintenance cost to support various wiring schemes in multiple-vendor environments, plus concomitant training costs for floor operators to become familiar with products from these vendors
• High operating costs for managing multiple-vendor environment because manufacturers must use different tools to monitor and diagnose equipment
• Lower productivity due to a limit of 2-Mbps transmission rate on the protocol used in the device network
• Large inventory of spare parts because manufacturers must keep spare parts for each vendor's equipment
• Slower equipment deployment as some vendors do not use standard wiring and configuration methods
The high cost of running networks on the manufacturing floor today drives manufacturers to consider a standard-based networking technology that delivers the same functions, if not more, at lower operating cost.
One obstacle to widespread acceptance of Ethernet on the manufacturing floor is device replacement. Whereas configuring new devices and rebooting are common occurrences on a corporate LAN, it is very important to have as little user intervention as possible when it comes to replacing devices on the manufacturing floor. This critical requirement also applies to IP address assignment: the replacement device must have the same IP address that was assigned to the device it is replacing. The IP address assignment must be done automatically so that the new device comes on line with little or no disruption of the production line.
You can manage IP address assignment by means of BOOTP (RFC 951) or Dynamic Host Configuration Protocol (DHCP, RFC 2131). Although both BOOTP and DHCP can assign a predefined IP address to a specific device based on its MAC address, floor workers still need to perform manual configuration tasks when replacing a device to ensure that the same IP address is assigned to the new device.
Manufacturers want to enjoy all the benefits of Ethernet and the ability to replace devices on the manufacturing floor with no human intervention to configure the new device.
SOLUTION
Cisco® CNS Network Registrar software helps enable efficient and effective provisioning of network devices and services. The software provides a complete Domain Name System (DNS), DHCP, and Trivial File Transfer Protocol (TFTP) server plus both graphical and scriptable command-line administrative functions to help you configure, automate, and streamline IP networking services.
Large enterprises and Internet service providers use Cisco CNS Network Registrar to efficiently administer DNS and DHCP services on large IP networks from Cisco Systems®. Its advanced architecture delivers high performance, scalability, and reliability, and its advanced provisioning features help businesses reduce network operational costs through faster and more reliable service rollouts and uninterrupted delivery of client services and data.
Cisco CNS Network Registrar supports DHCP Relay Agent Information Option (RFC 3046), also known as Option 82. This capability enables you to implement IP address or parameter assignment policies, such as assigning a device with the IP address that was previously assigned to the device it replaces.
Cisco CNS Network Registrar automates common tasks such as IP address assignment and management, DHCP and client policy definition and distribution, and server maintenance to simplify IP network configuration and administration. Features such as the Lightweight Directory Access Protocol (LDAP) directory interface help in integrating DNS and DHCP services with other network management and client or service provisioning applications. Together with fast setup and task execution functions, an availability-tuned architecture ensures reliable, consistent delivery of client services.
How the Solution Works
The Cisco CNS Network Registrar solution enables you to deploy Ethernet on the manufacturing floor with a single vendor. More importantly, it allows you to automate device configuration, including assignment of the same IP address to a replacement device without manual reconfiguration. The central idea of the solution is very simple: each device that is plugged to a port on the Cisco Catalyst® 3550 or 2950 Switch is assigned an IP address. When a device is replaced, the new one is assigned the same IP address. The software requires two pieces of information from the connection end-point's direct connected switch to uniquely identify a device and to generate a client-ID (CID) that can be used to uniquely identify a client on the network:
• The switch's MAC address, specified in the Switch Id field of the Option 82 packet
• The port number to which the device is connected, specified in the field Circuit Id
Getting IP Address
When a device is initially plugged in a port on the Cisco Catalyst 3550 or 2950 Switch, the switch generates an Option 82 DHCP packet containing its MAC address and the device's port number. The switch uses the Switch Id field to store the switch MAC address and the Circuit Id field for the port number to fully identify a device. If the manufacturing floor network is designed with a hierarchy of switches, the DHCP packet has the Switch Id field filled with the MAC address of the switch closest to all the manufacturing network devices. A switch receiving an Option 82 packet forwards the packet to the next switch in the hierarchy until it reaches Cisco CNS Network Registrar, which uses extension scripts to generate a unique ID comprising the MAC address specified in the Switch Id value and the port number. After Cisco CNS Network Registrar returns an IP address, it creates an entry to pair the IP address with the unique ID (Figure 2).
Figure 2. Obtaining Device Configuration
After the device is assigned, it establishes a connection with the Cisco CNS Configuration Engine to download the configuration parameters, configuring the device automatically. The Cisco CNS Configuration Engine can return a common set of configuration parameters for a group of IP addresses so that devices of the same type always get the same configuration when they are connected to the switch. Although the Cisco CNS Configuration Engine can retrieve configuration information based on a device's MAC address, it is more efficient to use the IP address; otherwise a new MAC address must be manually entered every time a new device is introduced. Effectively, this approach presents a standard way of configuring devices in a streamlined fashion.
Replacing Devices
When a device must be replaced, you simply connect the new device to the switch, which triggers a DHCP request sent to the switch. The switch formulates an Option 82 packet and sends it to Cisco CNS Network Registrar. The software looks up an IP address based on the unique ID formed by the MAC address and port number values, then returns the IP address to the new device. The device then downloads the configuration information from Cisco CNS Configuration Engine and can quickly become operational. The whole process is carried out without any operator intervention beyond physically replacing the broken device.
BUSINESS BENEFITS
With Cisco CNS Network Registrar software, you can move confidently from a proprietary network technology to a standard-based implementation without trade-offs. Moreover, the standard Ethernet network offers many advantages, including savings in capital cost, shorter learning time, and wide selection of vendors, while also delivering better manageability and hence lower operational cost.
Cisco CNS Network Registrar can reduce your need for networking experts to manage the Ethernet network. Enabling a device to retrieve its configuration data based on its assigned IP address, simple as it sounds, is not a trivial implementation because DHCP does not warrant assigning the same IP address to an IP client. But the flexibility of Cisco CNS Network Registrar coupled with its support for standard implementation allows devices to be configured without requiring a networking expert on site for every manual configuration task. Reduced human intervention means fewer operator errors and lower operating costs. As the complexity of managing the network grows with the increasing number of devices and addition of more services, Cisco CNS Network Registrar can easily meet these challenges without requiring a server upgrade.
Cisco CNS Network Registrar enables you to deploy Ethernet in the manufacturing network without having to staff networking experts to administer the network. Effectively, Cisco CNS Network Registrar lowers operational costs by making the networking of devices a plug-and-play procedure.
WHY CISCO
Although other vendors offer similar Ethernet-based products, Cisco is known for its networking solutions. As a strategic partner, Cisco helps its customers worldwide deploy standards-based networking services. Beyond delivering carrier-grade products and services, Cisco earns your trust for its commitment to help you protect your investment and grow your business. Cisco's partnership continues long after the products are delivered with extensive services to help ensure that your network is continuously operational.
