EQ-BGP: an efficient inter- domain QoS routing protocol Andrzej Bęben Institute of Telecommunications Warsaw University of Technology, Poland

Outline Introduction EQ-BGP protocol Performance of EQ-BGP Summary

Introduction (1) Providing end-to-end Quality of Service in IP networks still remains a challenging task: Different types of traffic and QoS objectives: VoIP, VTC, Multimedia Streaming, high throughput data,.. Different network technologies: LAN, WLAN, xDSL, UMTS, IP core, etc. Recognised approaches: single domain network: DiffServ, IntServ, MPLS – currently deployed in GENAT, Q-BONE, AQUILA,... multi-domain network:  Concept of end-to-end classes of service (e2e CoS) – ITU-T, IETF, IST EuQoS (  Path computation architecture (PCE IETF)  „user probing” approach ...

e2e CoSs concept (1) The end-to-end Classes of Service : represents a specific set of traffic requiring from network similar QoS guaranties, e.g. VoIP, multimedia, guaranteed throughput,... are offered to the users as „Globally Well Known” services are mapped into local CoSs offered inside particular domains and on inter-domain links

e2e CoSs concept (2) The QoS level offered by e2e CoSs depends on: QoS level offered by particular domains and inter- domain links The routing between source and destination However, BGP-4 establishes paths based on „AS path length” that may be not suitable Solution: to enhance BGP-4 protocol with QoS features => EQ-BGP (Enhanced QoS Border Gateway Protocol)

EQ-BGP protocol (1) Objective: to fix inter-domain routing paths that for particular e2e CoS offer the most attractive QoS level, e.g. lowest delay, jitter, losses,...

EQ-BGP protocol (2) New entities of EQ-BGP: New QOS_NLRI attribute of update messages, that carries information about e2e CoSs and values of QoS parameters, e.g. delay, jitter, losses, offered on a given AS path QoS aware decision algorithm, that allows to select paths taking into account QoS objectives of e2e CoS QoS assembling function, that calculates „aggregated” value of QoS parameters Multiple routing tables, as e2e CoSs usually need disjointed paths

RM A RM B RM C RM – Domain Resource Manager EQ-BGP protocol (3) AS A AS C AS B QoSPathDest QoSPathDest QoSPathDest QoSPathDest QCQC QCQC AS C QoSPathDest  RM C provides EQ-BGP router information about QoS offered inside domain C (Q C )  RM B provides EQ-BGP router information about QoS offered on inter-domain link B->C (Q B->C ) Q B->C QBQB AS B QoSPathDest  RM B provides EQ-BGP router information about QoS offered on inter-domain link B->C (Q B->C ) and offered by domain B QBQB Q A->B  RM A provides EQ-BGP router information about QoS offered on inter-domain link A->B (Q A->B )

EQ-BGP protocol (3) RM A RM B RM C AS A AS C AS B QoSPathDest QoSPathDest QoSPathDest QoSPathDest QCQC QCQC AS C QoSPathDest Q B->C QBQB AS B QoSPathDest QBQB Q A->B  Finally, all routers has information about QoS offered inside its domain and on inter-domains links. So, they start to exchange these information.  Router C sends message to router B with information about QoS offered by domain C Q B-C +Q C AS B AS C QoSPathDest  Router B writes new destination (AS C ) to his routing table with QoS corresponding to cumulative value of Q B->C and Q C (denoted as Q B->C +Q C ) using QoS NLRI attribute Q B->C +Q C  Then, it advertises these information to RM B and peering router in domain B using iBGP with QoS NLRI attribute QBQB AS B Q B + +Q B-C +Q C AS B AS C QoS Path Dest  This peering router updates routing table taking into account QOS offered by domain B Q B +Q B->C +Q C Q A-B +Q B AS A AS B Q A-B +Q B + Q B-C + +Q C AS A, AS B AS C QoSPathDest Q A->B + Q B +Q B->C +Q C Finally, router A updates its routing table and informs RM A about QoS towards domain C

Performance of EQ-BGP (1) Objective: to analyse the impact of new EQ-BGP entities on network convergence Methodology: We compare the performance of EQ-BGP with standard BGP-4 protocol based on convergence metrics: Network convergence time – time elapsing from the occurrence of stressing event till the end of processing the last update message Number of update messages that need to be exchanged NS2 is used for simulation experiments

Performance of EQ-BGP (2) Assumptions: Basic network stressing events: Advertisement of a new route Withdrawal of the existing one Each AS is represented by a single router Network topologies: Full mesh Ring Representative for the Internet (B.Premore, SSFnet) Different number of ASs A single e2e CoS targeted for assurance „mean delay” tree strategies for assigning QoS Representative Internet topology B.Premore, SSFnet

Performance of EQ-BGP (3) Convergence time after advertisement of new route: - randomly chosen AS advertises route simulation runs Conclusions: EQ-BGP gives stable routing Full mesh network converges independently from the applied protocol EQ-BGP protocol needs a bit more time to converge in case of ring and Internet topologies

Performance of EQ-BGP (4) Convergence time after withdrawal of route: - randomly chosen AS withdraws route simulation runs Conclusions: EQ-BGP gives stable routing EQ-BGP protocol converges faster then standard BGP-4

Summary The approach for providing e2e QoS in multi-domain network based on e2e CoSs was investigated The Enhanced QoS BGP protocol (EQ-BGP) was proposed for supporting e2e CoS concept Obtained preliminary simulation results confirm that: EQ-BGP gives stable routing Network convergence is similar to BGP-4 Further work: Evaluation of other stressing events, like link or node failure, route flapping Evaluation of scalability in large networks Evaluation in test-bed