SIGCOMM2006/INM1 Policy-based BGP Control Architecture for Autonomous Routing Management Osamu Akashi ＊, Kensuke Fukuda, Toshio Hirotsu, Toshiharu Sugawara NTT Network Innovation Labs.* National Institute of informatics Toyohashi University of Technology NTT Communication Science Labs.

SIGCOMM2006/INM2 Problems of Inter-AS Routing Difficulty in understanding the behavior Routing information mutates as it spreads. Each AS is controlled by independent administrators that has its own policy. Operators cannot flexibly adapt dynamically changing environment. Policy is mainly represented by low level primitives, namely router configuration commands. Control schemes for inter-domain (inter-AS) Nature of target Scope of control

SIGCOMM2006/INM3 Our Challenges Policy-based routing control Using conventional routers and not changing their configuration Current target: multi-homed AS, or ISP service for its customers and downstream ASs Flexible adaptation to environmental changes Policy control as a whole AS, like human operators do by configuring multiple border routes Controls outgoing packets VR(virtual router / BGP-controller) approach Uses iBGP sessions for controlling conventional BGP routers Controls Incoming packets Uses cooperation among agents Try to support operators ’ actions

SIGCOMM2006/INM4 Our Approach: Control Model AS agent AS agent BGP information router Inter-AS coordination among distributed agents Observation and control through VR Observed results (network status) Adaptive control based on acquired results and given policy VR Policy description VR policy Policy router

SIGCOMM2006/INM5 Merits of CDPS Approaches Coincides with BGP control structure (ASs) Request-and-acceptance basis rather than centralized control methods Autonomy at each AS Acts on each policy description Hides detailed routing information ex.) private peers, internal topology Operation availability Ex.) Message relaying

SIGCOMM2006/INM6 Multi-agent Platform Diagnosis for inter-AS routing anomalies ENCORE[3,4]: cooperative observation and analysis Deployed to commercial ISPs. Flexible intra- and inter-AS policy-based control AISLE (Autonomous and Intelligent Self-control Environment) Controls conventional border routers in its AS through VR Uses extended agent platform

SIGCOMM2006/INM7 Agent Group Management

SIGCOMM2006/INM8 Requirements for AISLE / VR Router Configuration primitive Routing control Operators Control policies Network - Low level primitives - Static configuration - No coordination with protocols or other events Desire to represent policies that can manage temporal or spatial traffic- changes. Desire to act based on observing results of network status

SIGCOMM2006/INM9 Structure of AISLE Agent / VR Policy control engine VR (BGP controller) Cooperative action controller Policy description Router Configuration commands iBGP session Exchanges modified BGP entry agent Communication / cooperation Agent In other AS eBGP session Abstracted: intuitively, complicated and application dependent functions Status information Control (by RPC)

SIGCOMM2006/INM10 AISLE / VR Control Layer Defined in proc.

SIGCOMM2006/INM11 VR Architecture (#1) agent VR Policy description Router y Router x Router z BP: Prefix : local_pref: next_hop: ID: flag : a.b.c.0: 1000 : x.x.x.1 : x : : 500 : y.y.y.1 : y > : : 2000 : z.z.z.1 : z iBGP connection WD:C AD: the best path WD:

SIGCOMM2006/INM12 VR Architecture (#2) agent VR Policy description Router y Router x Router z BP: Prefix : local_pref: next_hop: ID: flag : a.b.c.0: 1000 : x.x.x.1 : x : : 500 : y.y.y.1 : y > : : 2000 : z.z.z.1 : z > : a.b.c.0: 3000 : y.y.y.1 iBGP connection AD: current BP with the lowest l_p(=10) WD:C AD: created entry WD : WD:C AD: (again)

SIGCOMM2006/INM13 Ex1) Change of the Best Paths Advertising BGP full-routes Changes of the best paths by VR / AISLE

SIGCOMM2006/INM14 Times for Changing the BGP Best Paths

SIGCOMM2006/INM15 VR (repeat) feedback (repeat) Ex2) Simple Load Balancing Per Peer AS for Outgoing Packets AS AS x agent AS Status information that are only acquired after actual observation: - BGP peers - Load per peers - Number of best paths per peer Insert new entries whose next_hop are changed to a less loaded AS. BGP entry Border router: Adopt a new entry as the best path and traffic is partially moved. observation

SIGCOMM2006/INM16 Ex2) Control of Outgoing Packets (#1) Advertising 256 * 3 of IP-prefix (/24)

SIGCOMM2006/INM17 Traffic monitoring interfaces Ex2) Control of Outgoing Packets (#2) Sending traffic to received IP- prefixes (256 * 3) ( = 768 streams) Traffic control by VR / AISLE

SIGCOMM2006/INM18 Ex3) Control of Incoming Packets (#1) Advertising 256 * 3 of IP-prefix (/24)

SIGCOMM2006/INM19 Ex3) Control of Incoming Packets (#2) Sending traffic to received IP-prefixes (256 * 3) ( = 768 streams) Traffic monitoring interfaces Sending preference Traffic control by VR / AISLE

SIGCOMM2006/INM20 Future Work Experiments of various cooperative scenarios at the inter-agent level Deployed targets Realistic topologies Using actual BGP update messages at different observation points Routing flapping problems Verification of system stability Redundant backup (like route reflectors) Modification and extension of policy description

SIGCOMM2006/INM21 Conclusion AISLE/VR: intra- and inter-AS flexible policy- based routing control architecture Implemented only by ACL/CLOS on PCs Controls conventional routes by standard BGP protocols Needs more experiments Verification and feedback