Providing scalable NH-diverse iBGP route re-distribution to achieve sub-second switch-over time

Cristel Pelsser, Steve Uhlig, Tomonori Takeda, Bruno Quoitin, and Kohei Shiomoto. 2010. Providing scalable NH-diverse iBGP route re-distribution to achieve sub-second switch-over time. Computer Networks 54 (14), 2492–2505. https://doi.org/10.1016/j.comnet.2010.04.007

@article{Pelsser2010,
	title        = {Providing scalable NH-diverse iBGP route re-distribution to achieve sub-second switch-over time},
	author       = {Cristel Pelsser and Steve Uhlig and Tomonori Takeda and Bruno Quoitin and Kohei Shiomoto},
	year         = 2010,
	month        = apr,
	journal      = {Computer Networks},
	volume       = 54,
	number       = 14,
	pages        = {2492--2505},
	doi          = {10.1016/j.comnet.2010.04.007},
	abstract     = {The role of BGP inside an AS is to disseminate the routes learned from external peers to all routers of the AS. A straightforward, but not scalable, solution, is to resort to a full-mesh of iBGP sessions between the routers of the domain. Achieving scalability in the number of iBGP sessions is possible by using Route Reflectors (RR). Relying on a sparse iBGP graph using RRs however has a negative impact on routers’ ability to quickly switch to an alternate route in case of a failure. This stems from the fact that routers do not often know routes towards distinct next-hops, for any given prefix. In this paper, we propose a solution to build sparse iBGP topologies, where each BGP router learns two routes with distinct next-hops (NH) for each prefix. We qualify such iBGP topologies as NH-diverse. We propose to leverage the “best-external” option available on routers. By activating this option, and adding a limited number of iBGP sessions to the existing iBGP topology, we obtain NH-diverse iBGP topologies that scale, both in number of sessions and routing table sizes. We show that NH diversity enables to achieve sub- second switch-over time upon the failure of an ASBR or interdomain link. The scalability of our approach is confirmed by an evaluation on a research and a Service Provider network.},
	bibsource    = {dblp computer science bibliography, https://dblp.org},
	biburl       = {https://dblp.org/rec/journals/cn/PelsserUTQS10.bib},
	groups       = {International Journals and Magazines},
	keywords     = {BGP, iBGP topology design, diversity, fast-recovery}
}