A comparative study of architectural impact on BGP next-hop diversity

—Large ISPs have been growing rapidly in both the size and global connectivity. To scale with the sheer number of routers, many providers have replaced the flat full-mesh iBGP connectivity with a hierarchical architecture, using either Route-Reflection (RR) or AS confederation. Given that each intermediate iBGP router in the hierarchy selects and propagates only one best path per destination network, there is a common perception that, compared to full-mesh, a hierarchical iBGP connectivity is likely to lose sight of alternative paths to external destinations. To gauge the path diversity reduction in the operational networks, we performed a comparative study by using iBGP data collected from two global-scale ISPs, with fullmesh core and RR architecture respectively. Our results show that both ISPs suffer a significant reduction (up to 42%) in the overall path diversity. However the specifics of different iBGP architectures only made a minor impact (less than 2.9%) on this reductio...

• Type: Journal
• Year: 2012
• Where: INFOCOM
• Authors: Jong Han Park, Pei-chun Cheng, Shane Amante, Dorian Kim, Danny McPherson, Lixia Zhang
• Keywords: Communications, External Destinations, Global Connectivity, Hierarchical Architecture, INFOCOM 2012