A Modular RCP for Flexible Interdomain Route Control

1. 2. Principles for better route control 1. Problem Facts: Network operators often have many different objectives in mind when they configure BGP Business Relationships • Network-wide visibility: network-wide visibility enables network-wide optimality and prevents routing inconsistencies (e.g., loops, blackholes, and oscillation) • Decouple interdomain routing from intradomain routing: BGP routing decisions should not be affected by IGP route changes • Extensibility for new functionalities and services: network operators should be able to implement new BGP extensions without wait for IETF and vendors BGP policy configurations for each router • Current solution: • Network-level objectives must be decomposed into router configurations for every router in the AS • Largely a black art… Traffic Engineering Some miracle occurs… A Modular RCP for Flexible Interdomain Route Control Routing Security Resource Constraints 3. Modular Routing Control Platform (MRCP) Complete control and visibility Tunneling for a “BGP-free” core • Logically centralized control of interdomain routing in an AS • MRCP learns all the BGP routes from neighbor ASes through eBGP – complete view of the network • Pick the best route per prefix for each router individually – direct control and backward compatibility • Stateless tunnels between ingress-egress pairs prevent loops and isolate BGP decisions from intradomain route changes • Great scalability benefits: • a “BGP-free” core • MRCP only needs to talk to edge routers • Tunneling (MPLS or IP-in-IP) is already commonly used in ISPs and can be performed at line rate by high end routers Yi Wang and Jennifer Rexford Department of Computer Science, Princeton University, USA Ranking of egress routers Route compression • A configurable rank with each ingress-egress tunnel • MRCP may pick different egress point for different traffic ingress point to reach the same prefix • Tunneling + ranking provides a new tie-breaking scheme in BGP route selection process and a flexible interface for better TE • Local edge routers now only needs enough information to do forwarding, i.e., the “prefix – next-hop” pair • MRCP strips all the extra attributes before sending the best routes to local edge routers 4. Implementation • Implemented as a pipeline of modules – easy to make replacement of existing functions and introduce / share new functions • New BGP extensions (e.g., anomaly detection, traffic engineering) are implemented as new modules • Easy for network operators to insert modules developed by third parties or develop their own • Design and evaluation of prototype as an extension to XORP