Transcript Q B->C
EQ-BGP: an efficient interdomain QoS routing protocol Andrzej Bęben ([email protected]) 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 (www.euqos.org) 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 Telephony Telephony RT Interact. RT RT MM Stream. NRT NRT High Thr. D. BE BE Overprovisi oned RT RT RT Interact. NRT NRT MM Stream. BE BE High Thr. D. Standard Standard Access 1 (WLAN) Core Access 2 (UMTS) e2e CoSs concept (2) The QoS level offered by e2e CoSs depends on: QoS level offered by particular domains and interdomain 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,... AS4 AS1 AS6 AS2 AS – BGP Autonomous System – BR routers --- Best Effort link RM --- QoS link AS3 T31 AS5 --- AS path 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 DoP (Q1, Q 2,..., f 1, f 2,..) f1 f2 ... max 0, T1 q1 max 0, T2 q2 QoS assembling function, that calculates „aggregated” value of QoS parameters Multiple routing tables, as e2e CoSs usually need disjointed paths EQ-BGP protocol (3) RMB RMA AS A Dest RMC AS B Path QoS QA->B Dest Path QoS ASB ASB QB QB AS C Dest Path QoS QB->C Dest Path QoS ASC ASC QC QC RM RMABB provides provides EQ-BGP EQ-BGP router router information information about about QoS RM router information about on inter-domain link A->B ) B->C QoS offered onEQ-BGP inter-domain link B->C (Q (QA->B RMCoffered –provides Domain Resource Manager B->C B->C) QoS offered by inside domain and offered domain B C (QC) EQ-BGP protocol (3) RMB RMA AS A RMC AS B Dest Path ASB Dest ASA QA-B Path QoS ASB +QB ASC ASA, ASB ASC AS C QoS QA-B +QB+ QB-C+ +QC QA->B Dest Dest Path Path QoS QoS AS ASBB ASC AS B AS B ASB ASC Path QoS QBQ B QB+ +QB-C +QC QB Dest Path QoS ASC ASB ASC QB-C +QC QB->C Dest Path QoS ASC ASC QC QC Finally, router QB->C+QC A updates its routing table QBto +Qrouter Ball writes newhas destination (AS ) to his routing and sends message information B->C+Q C Babout informsC Router Finally, routers information QoS offered Cwith about Then, it information to RM and table with QoS corresponding to cumulative QoS offered by domain C RMA about Q +these Q +Qrouting inside itsadvertises domain onB->C inter-domains links. So,peering they Bvalue This peering router updates table A->Band B+Q C of Qtowards and QC (denoted as Qwith using QoS NLRI router in domain B these using iBGP QoS QoS B->C B->C C) NLRI start to exchange information. taking into account QOS offered by+Q domain Battribute domain C attribute 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 - 100 simulation runs BGP-4 Network type No. of ASs “Full mesh” 4 11 29 4 11 29 29 “Ring” “Internet” mean [ms] 3.550,0 3.550,0 3.550,0 6,50,028 10,840,0 28,20,0 11,920,028 max [ms] 3.55 3.55 3.55 8,22 10,85 28,2 15,31 random mean [ms] 3.550,0 3.550,0 3.550,0 6,780,028 12,940,028 51,450,045 17,90,076 max [ms] 3.55 3.55 3.55 8,22 14,6 53,94 27,38 EQ-BGP increasing mean [ms] 3.550,0 3.550,0 3.550,0 7,640,023 13,320,025 47,260,05 13,590,06 max [ms] 3.55 3.55 3.55 8,22 14,6 50,4 20,38 decreasing mean max [ms] [ms] 3.55 3.550,0 3.55 3.550,0 3.55 3.550,0 8,22 6,790,028 14,6 13,490,027 50,4 47,790,06 27,36 18,970,065 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 - 100 simulation runs BGP-4 Network type No. of ASs “Full mesh” 4 11 4 11 29 29 “Ring” “Internet” mean [ms] 16,750,03 18546,13 8,220,03 20,030,0 53,940,0 187213 max [ms] 18,47 2077 9,56 20,03 53,94 2808 random mean [ms] 16,830,03 717,24,21 7,890,03 17,840,03 51,450,05 121265 max [ms] 18,47 1139 9,56 20,03 53,94 1706 EQ-BGP increasing mean [ms] 17,040,03 12753,5 6,890,02 17,520,02 47,260,05 265423 max [ms] 18,47 1544 9,56 20,03 50,4 4042 Conclusions: EQ-BGP gives stable routing EQ-BGP protocol converges faster then standard BGP-4 decreasing mean max [ms] [ms] 12,49 12,490,0 708,8 576,51,7 9,56 7,890,03 20,03 17,520,02 50,4 47,790,06 5241 232826 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