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Location-dependent network address assignment in redundant networks Disclosure Number: IPCOM000010658D
Original Publication Date: 2003-Jan-07
Included in the Prior Art Database: 2003-Jan-07
Document File: 3 page(s) / 34K

Publishing Venue



Extensions to the BOOTP protocol are presented that support the identification and spatial location of IP hosts within specific forms of intranets. The assignment of IP addresses can be directed with respect to the spatial location of subject IP hosts.

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Location-dependent network address assignment in redundant networks


Extensions to the BOOTP protocol are described that enable the dynamic assignemnt of IP addresses to controllers beased on spatial or location-dependent information.

The BOOTP protocol revisited

    Within the internet domain the BOOTP protocol has been architected by Request for Comment RFC 1542 to service diskless computer systems by supplying an executable load image. A so-called boot server host will be attached to the same physical LAN that also connects the diskless, mostly embedded controller computer nodes. When the embedded nodes receive stand-by power they typically load an initial bootstrap code and start executing it. In the course of this execution important information that personalizes this local node is read from special hardware interfaces. This information is usually divided into two categories:
(I). Data that is required to service the BOOTP protocol (for instance, MAC addresses).
(II). Vendor specific data that is unique to the environment of the implementation. The boot code starts sending out BOOTP messages over one or all of its local LAN interfaces. Sending is repeated upon expiration of an appropriate timeout until a reply is received from a boot server. The sending is performed as a "limited broadcast" on the LAN by supplying a MAC address with all bits on. These message contain data of both types (I) and (II). These BOOTP messages will be intercepted by the boot server host. Based on the data content a dialogue between the boot server program and the target BIOS code will be conducted. At the end of this dialogue a loadable code image will be shipped to the embedded node, and this image will be started then.

The problem

    The BOOTP RFC assumes access to a local file called the BOOTPTAB typically located as /etc/bootptab. For user-controlled workstation networks this file contains the required information to feed the BOOTP reply messages with the necessary data (IP addresses) to boot the requesting meachine.

    But in an environment that features redundant network structures with redundant components, new problems arise if the following requirements are postulated:
1. The is more than one boot server attached to the redundant network.
2. The network addressing schema (assignment of IP addresses to LAN interfaces of nodes) is to be governed by specific rules. For instance, the set of IP addresses assi...