Workshop on IP QoS and Traffic Control RSVP-TE Extensions for LSP Rerouting in NS2 D. Adami, C. Callegari, S. Giordano, M. Pagano Department of Information Engineering - University of Pisa 6-7 December 2007 IST Congress Center, Lisbon, Portugal Michele Pagano 1
Outline • Introduction • MPLS-based Recovery • RSVP-TE Reservation Styles • NS2 Software Modules • Simulations Results • Conclusions Michele Pagano 2
Introduction • Multiprotocol Label Switching (MPLS) provides: � Traffic Engineering capabilities � Virtual Private Networks support � Network Survivability Egress LSR (Label popping) (Label popping) Egress LSR Transit LSR (Label swapping) Transit LSR (Label swapping) Ingress LSR (Label pushing) Ingress LSR (Label pushing) In In Address Out Out In In Out Out Address I/F Lab Prefix I/F Lab I/F Lab Prefix I/F Lab In In Address Out Out - 3 40 172.16 1 3 30 172.16 1 40 I/F Lab Prefix I/F Lab ... ... ... ... ... - ... ... ... ... ... 3 172.16 1 30 ... ... ... ... ... LSR B LSR B 40 172.16.1.2 data 172.16.0.0/16 LSR A LSR A LSRC LSRC 30 172.16.1.2 data 172.58.0.0/16 172.16.1.2 data 172.16.1.2 data Michele Pagano 3
IP Routing R8 R1 R3 R4 R2 Shortest Path LSR8 R5 R9 R7 R6 High Convergence Time! Issues Issues � Highly reliable services require very low recovery times (tenths of ms) � IP routing does not assure QoS recovery Michele Pagano 4
MPLS Recovery: Path Protection Egress LER LSR1 LSR3 LSR4 LSR2 LSR8 LSR5 Ingress LER LSR7 LSR6 Working LSP MPLS-based Recovery aims at reducing the recovery times Backup Path when a failure occurs and dynamic routing protocols are used! Michele Pagano 5
MPLS Recovery: Path Restoration Egress LER LSR1 LSR3 LSR4 LSR2 LSR8 LSR5 Ingress LER LSR7 LSR6 MPLS- -based based Recovery Recovery Objectives Objectives MPLS � Optimal use of network resources Working LSP � Traffic protection with different granularity Backup Path � Minimization of unprotected traffic degradation Michele Pagano 6
The Recovery Cycle Egress LSR1 Resv LER LSR3 LSR4 LSR2 PathErr PathTear LSR8 LSR5 Ingress LER LSR7 LSR6 Path Recovery Recovery Fault Detection Fault Detection Fault Hold Fault Hold- -off off Fault Fault Notification Notification Traffic Recovery Traffic Recovery Operation Operation Time Time Time Time Time Time Time Time Time Time Start of Recovery Path Network Fault Start of Recovery Operation Traffic Impairment Detected Notification Operation Complete Recovered Michele Pagano 7
RSVP-TE Reservation Styles Distinct Reservation Shared Reservation Fixed-Filter Shared-Explicit Explicit Sender Selection (FF) style (SE) style Wildcard-Filter Wildcard Sender Selection (WF) style • A reservation style indicates whether senders in the RSVP session have distinct or shared resource reservation and whether they are selected according to an explicit list • RSVP defines three different Reservation Styles – the FF style creates a distinct reservation for each sender – the SE style allows a receiver to make a single reservation shared by a set of senders explicitly specified in the reservation message – the WF style creates a single reservation that is shared by all senders in the session Michele Pagano 8
RSVP-TE Reservation Styles: Application Scenario B C (2,100) LSP (A_B_C_F) (1,100) (1,50) 40 Mbps A F (2,100) (1,100) (1,50) Bandwidth (1,50) (1,100) 70 Mbps (5,100) D E (Metric, Bandwidth) New Path A_D_B_C_F Without SE Reservation Style, it is necessary to tear down the old LSP and to set-up a new LSP Michele Pagano 9
Motivations and targets • Since planning MPLS-based recovery strategies involves trade-offs based on several factors � End-user applications requirements � Network efficiency � Complexity � Revenues our goal was to develop a powerful and flexible simulation tool to help network designers and administrators in their work • An MPLS Network Simulator (MNS) was available for the Network Simulator 2 (NS2) � developed at Chungnam National University, Korea � based on the Constrained Routing – Label Distribution Protocol (CR-LDP) but…a full open-source MPLS networks simulation tool had not been realized yet!! Michele Pagano 10
NS2 Software Modules Old Modules MNS - MPLS Network Simulator RSVP-TE\ns with Reservation Styles OSPF-TE\ns New Modules MPLS Recovery Strategies QoS Routing Michele Pagano 11
New MPLS Node Architecture in NS2 RSVP-TE RSVP-TE module module OSPF-TE OSPF-TE module module Michele Pagano 12
LSP Recovery in NS2 • LSP Protection <Ingress-LSR> protection-ff <Source> <Egress> <Dest> <OldSID> <SessionID> <FlowID> <TunnelID> <Rate> <Buffer> <Er> <Ingress-LSR> protection-se <Source> <Egress> <Dest> <OldSID> <SessionID> <FlowID> <TunnelID> <Rate> <Buffer> <Er> • LSP Rerouting with Path Precomputation <Ingress-LSR> fastrerouting-ff <Source> <Egress> <Dest> <OldSID> <FlowID> <TunnelID> <Rate> <Buffer> <Er> <Ingress-LSR> fastrerouting-se <Source> <Egress> <Dest> <OldSID> <FlowID> <TunnelID> <Rate> <Buffer> <Er> Michele Pagano 13
Simulation Scenario GÉANT • Pan-European multi-gigabit data communications network specifically reserved for research and education use • The GÉANT project was a collaboration between 26 National Research and Education Networks representing 30 countries • The network connects a total of 34 countries Michele Pagano 14
Simulation Scenario CBR Traffic Destination Simulation Scenario • Available Bandwidth = 1 Mb/s • CBR Sources at 400 Kb/s • Link cost = 1 • A failure on the link 7_22 of the primary LSP is forced • Fault Hold-off Time = 0 Target Target • To highlight the advantages of Primary Primary using SE Reservation Styles LSPs LSPs CBR Traffic Source Michele Pagano 15
LSP Rerouting with FF Reservation Style Reserved LSP Back-Up LSPs Destinations CBR Traffic Sources Michele Pagano IP Shortest Path PRIMARY LSPs 16
Recovery Time for FF Reservation Style LSP 1 LSP 2 780 760 740 720 ms 700 680 660 640 620 1 2 3 4 5 6 7 8 9 10 Simulation Link status is checked by a polling mechanism, simulated as a random variable uniformely distributed within [0, 100 ms] Michele Pagano 17
LSP Rerouting with SE Reservation Style Reserved LSP Back-Up LSP Destinations CBR Traffic Sources Michele Pagano PRIMARY LSP 18
Recovery Time for SE Reservation Style 180 160 140 120 100 ms 80 60 40 20 0 1 2 3 4 5 6 7 8 9 10 Simulation Avg. Recovery Time: 126 ms vs. 736 ms Michele Pagano 19
Conclusions • Design and development of a new NS2 software module which enhances RSVP-TE\ns with the reservation styles supported by RSVP-TE • The availability of reservation styles allows MPLS network designers to plan complex scenarios with heterogeneous recovery strategies • The new NS2 module may help a network designer to choose the most suitable MPLS-based recovery strategy • Reservation styles are also essential to set-up Point-to-Multipoint and Multipoint-to-Multipoint LSPs • The software is available on the TlcNetGroup software repository at the site: http://netgroup-serv.iet.unipi.it Michele Pagano 20
Recommend
More recommend
