手法を比較

	Border Gateway Protocol (BGP)	DiffServ（Differentiated Services）	OSPF（Open Shortest Path First）
分野	通信工学	通信工学	通信工学
系統	Process / pipeline	Process / pipeline	Process / pipeline
提唱年	1989	1998	1998
提唱者	IETF Routing Protocols Working Group	IETF DiffServ Working Group	John Moy
種類	path-vector routing protocol	QoS architecture	link-state routing protocol
原典	Rekhter, Y., Li, T., & Hares, S. (2006). A Border Gateway Protocol 4 (BGP-4). RFC 4271.	Blake, S., Black, D., Carlson, M., et al. (1998). An Architecture for Differentiated Services. RFC 2475.	Moy, J. T. (1998). OSPF Version 2. RFC 2328.
別名	exterior gateway protocol, inter-domain routing	quality of service, QoS architecture	link-state routing, intra-domain routing
関連	2	3	2
概要	BGP is the de facto standard routing protocol for interconnecting autonomous systems (ASs) on the Internet. Since its introduction in 1989, BGP has scaled the Internet to millions of routers and trillions of destinations. BGP is path-vector-based, using a flexible policy system to control route propagation and selection. While BGP convergence can be slow and policies complex, it remains the only viable protocol for Internet-scale inter-domain routing.	DiffServ is a QoS architecture providing scalable, class-based service differentiation in networks. Introduced by IETF (1998), DiffServ marks packets with a Differentiated Services Code Point (DSCP) in the IP header, enabling routers to apply per-hop-behaviors (PHBs) based on markings. Unlike IntServ (which reserves resources per-flow), DiffServ is stateless and scalable to Internet scale. DiffServ remains the primary QoS mechanism in ISP and enterprise networks.	OSPF is a link-state interior gateway protocol (IGP) for routing within an autonomous system. Introduced by John Moy in 1998, OSPF converges faster than distance-vector protocols and supports equal-cost multipath (ECMP). It remains widely deployed in enterprise and ISP networks for intra-domain routing, though IS-IS is increasingly preferred in large backbones.