Route advertisement policies for border gateway protocol with provider aggregatable addressing

摘要

This paper proposes route advertisement policies (RAP) for the Border Gateway Protocol (BGP) with provider aggregatable (PA) addressing. The proposed RAP takes the advantage of address aggregation opportunity. If multiple address spaces are allocated to each of autonomous systems (ASes) that are multihomed to multiple upper ASes, reduction of the Forwarding Information Base (FIB) and quick convergence are achieved. However, multihoming based on PA addressing poses two limitations. One, more specific address information is hidden due to address aggregation. Two, multiple allocated address spaces per AS cause an address selection problem. To cope with these two limitations, we propose RAP to ensure connectivity among ASes with fewer routes installed in the FIB of each top layer AS. We implement the proposed RAP in an emulation environment with BGP (using the Quagga software suite) and our developed Hierarchical Automatic Number Allocation (HANA) protocols. We use HANA as a tool to automatically allocate hierarchical PA addresses to ASes. We confirm that with our proposed policies the FIB and RIB (Routing Information Base) sizes in top layer ASes do not change with the increase of stub ASes, and number of exchanged BGP update messages are reduced up to 67.3% than that of the case with conventional BGP RAP.