SNMP Management in a Distributed Software Router Architecture

Multi-stage software router architectures permit to overcome several limitations of single-stage software routers, allowing to expand the number of available interfaces and to increase the overall throughput. However, a multi-stage software router, despite being composed by several internal elements, must externally appear as a single device. A control protocol called DIST was defined to solve this problem from the control plane point of view for a previously proposed multi-stage architecture. In this paper, we tackle the same problem from the network management point of view. We define a management architecture and a manager-agent communication model to coordinate the information residing on the single elements of the multi-stage router to present a unified view to the external network management station issuing SNMP requests. We analyze the different variable types contained in the SNMP MIB-II and divide them into different categories depending on how the response to a SNMP request is compiled. The handling methods used to create the proper response to SNMP request for the different types of MIB variables are described. Analytical computations show that the proposed management architecture does not affect the multi-stage software router scalability.