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EQ-BGP: an efficient inter-domain QoS routing protocol

EQ-BGP: an efficient inter-domain QoS routing protocol. Andrzej Bęben (abeben@tele.pw.edu.pl) Institute of Telecommunications Warsaw University of Technology , Poland. Outline. Introduction EQ-BGP protocol Performance of EQ-BGP Summary. Introduction (1).

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EQ-BGP: an efficient inter-domain QoS routing protocol

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  1. EQ-BGP: an efficient inter-domain QoS routing protocol Andrzej Bęben (abeben@tele.pw.edu.pl) Institute of Telecommunications Warsaw University of Technology, Poland

  2. Outline • Introduction • EQ-BGP protocol • Performance of EQ-BGP • Summary

  3. 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 (www.euqos.org) • Path computation architecture (PCE IETF) • „user probing” approach • ...

  4. 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

  5. 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)

  6. 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,...

  7. 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

  8. RMB RMA RMC AS A AS B AS C Dest Path QoS Dest Path QoS Dest Path QoS Dest Path QoS Dest Path QoS Dest Path QoS ASC ASC QC ASB ASB QB QA->B QC QB QB->C • RMA provides EQ-BGP router information about QoS offered on inter-domain link A->B (QA->B) • RMB provides EQ-BGP router information about QoS offered on inter-domain link B->C (QB->C) and offered by domain B • RMB provides EQ-BGP router information about QoS offered on inter-domain link B->C (QB->C) • RMC provides EQ-BGP router information about QoS offered inside domain C (QC) RM – Domain Resource Manager EQ-BGP protocol (3)

  9. RMB RMA RMC AS A AS B AS C Dest Path QoS Dest Path QoS ASB ASA ASB QA-B +QB Dest Path QoS Dest Path QoS Dest Path QoS Dest Path QoS Dest Path QoS Dest Path QoS Dest Path QoS ASB ASB QB ASC ASA, ASB ASC QA-B +QB+ QB-C+ +QC ASC ASC QC ASB ASB QB ASC ASB ASC QB+ +QB-C +QC ASC ASB ASC QB-C +QC Finally, router A updates its routing table and informs RMAabout QoS towards domain C QB->C+QC QB+QB->C+QC • Router B writes new destination (ASC) to his routing table with QoS corresponding to cumulative value of QB->C and QC (denoted as QB->C+QC) using QoS NLRI attribute • Router C sends message to router B with information about QoS offered by domain C • Then, it advertises these information to RMB and peering router in domain B using iBGP with QoS NLRI attribute • This peering router updates routing tabletaking into account QOS offered by domain B QA->B + QB+QB->C+QC EQ-BGP protocol (3) QA->B QC QB QB->C • Finally, all routers has information about QoS offered inside its domain and on inter-domains links. So, they start to exchange these information.

  10. 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

  11. Representative Internet topology B.Premore, SSFnet 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

  12. Performance of EQ-BGP (3) Convergence time after advertisement of new route: - randomly chosen AS advertises route - 100 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

  13. Performance of EQ-BGP (4) Convergence time after withdrawal of route: - randomly chosen AS withdraws route - 100 simulation runs Conclusions: • EQ-BGP gives stable routing • EQ-BGP protocol converges faster then standard BGP-4

  14. 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

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