Post on 26-Dec-2015
EQ-BGP: an efficient inter-domain QoS routing protocol
Andrzej Bęben
(abeben@tele.pw.edu.pl)
Institute of TelecommunicationsWarsaw University of Technology,
Poland
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” servicesare mapped into local CoSs offered inside particular domains and on inter-domain links
Access 1 (WLAN)
Access 2 (UMTS)
Core
Telephony
RT Interact.
MM Stream.
High Thr. D.
Standard
RT
NRT
BE
Over - provisi oned
RT
NRT
BE
RT
NRT
BE
RT
NRT
BE
Telephony
RT Interact.
MM Stream.
High Thr. D.
Standard
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,...
AS – BGP Autonomous System
– BR routers
--- Best Effort link
--- QoS link
--- AS path
AS1AS6
AS2
AS5
AS4
AS3
RM
T31
AS – BGP Autonomous System
– BR routers
--- Best Effort link
--- QoS link
--- AS path
AS1AS6
AS2
AS5
AS4
AS3
RM
T31
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
...,0max,0max
,..)2,1,...,2,1(22
2
11
1
qT
f
qT
fffQQDoP
RMARMB RMC
RM – Domain Resource Manager
EQ-BGP protocol (3)
AS A AS CAS B
QoSPathDestQoSPathDestQoSPathDest QoSPathDest
QC
QCASCASC
QoSPathDest
RMC provides EQ-BGP router information about QoS offered inside domain C (QC)
RMB provides EQ-BGP router information about QoS offered on inter-domain link B->C (QB->C)
QB->C
QBASBASB
QoSPathDest
RMB provides EQ-BGP router information about QoS offered on inter-domain link B->C (QB->C) and offered by domain B
QBQA->B
RMA provides EQ-BGP router information about QoS offered on inter-domain link A->B (QA->B)
EQ-BGP protocol (3)RMA
RMB RMC
AS A AS CAS B
QoSPathDestQoSPathDestQoSPathDest QoSPathDest
QC
QCASCASC
QoSPathDest
QB->C
QBASBASB
QoSPathDest
QBQA->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
QB-C
+QC
ASB
ASC
ASC
QoSPathDest
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
QB->C+QC
Then, it advertises these information to RMB and peering router in domain B using iBGP with QoS NLRI attribute
QBASBASB
QB+
+QB-C
+QC
ASB
ASC
ASC
QoSPathDest
This peering router updates routing tabletaking into account QOS offered by domain B
QB+QB->C+QC
QA-B
+QB
ASA
ASB
ASB
QA-B
+QB+
QB-C+
+QC
ASA,
ASB
ASC
ASC
QoSPathDest
QA->B + QB+QB->C+QC
Finally, router A updates its routing table and informs RMA 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 routerNetwork 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 QoSRepresentative 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
EQ-BGP BGP-4 random increasing decreasing Network
type No. of ASs mean
[ms] max [ms]
mean [ms]
max [ms]
mean [ms]
max [ms]
mean [ms]
max [ms]
4 3.550,0 3.55 3.550,0 3.55 3.550,0 3.55 3.550,0 3.55 11 3.550,0 3.55 3.550,0 3.55 3.550,0 3.55 3.550,0 3.55
“Full mesh”
29 3.550,0 3.55 3.550,0 3.55 3.550,0 3.55 3.550,0 3.55
4 6,50,028 8,22 6,780,028 8,22 7,640,023 8,22 6,790,028 8,22 11 10,840,0 10,85 12,940,028 14,6 13,320,025 14,6 13,490,027 14,6 “Ring” 29 28,20,0 28,2 51,450,045 53,94 47,260,05 50,4 47,790,06 50,4
“Internet” 29 11,920,028 15,31 17,90,076 27,38 13,590,06 20,38 18,970,065 27,36
Conclusions:EQ-BGP gives stable routingFull mesh network converges independently from the applied protocolEQ-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
EQ-BGP BGP-4 random increasing decreasing Network
type No. of ASs mean
[ms] max [ms]
mean [ms]
max [ms]
mean [ms]
max [ms]
mean [ms]
max [ms]
4 16,750,03 18,47 16,830,03 18,47 17,040,03 18,47 12,490,0 12,49 “Full mesh” 11 18546,13 2077 717,24,21 1139 12753,5 1544 576,51,7 708,8
4 8,220,03 9,56 7,890,03 9,56 6,890,02 9,56 7,890,03 9,56 11 20,030,0 20,03 17,840,03 20,03 17,520,02 20,03 17,520,02 20,03 “Ring” 29 53,940,0 53,94 51,450,05 53,94 47,260,05 50,4 47,790,06 50,4
“Internet” 29 187213 2808 121265 1706 265423 4042 232826 5241
Conclusions:EQ-BGP gives stable routingEQ-BGP protocol converges faster then standard BGP-4
SummaryThe 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