Download Hardware and Software Fault Tolerance

Fault Tolerance for MPLS
Supervisor Professor :林振緯
Speaker : 蘇文宏
Computer Science and Information Engineering Department
Fu Jen Catholic University
Contents
•OverView for MPLS
•Hardware and Software Fault Tolerance
An Efficient Recovery Mechanism for MPLS-based Protection LSP
Simulator for MPLS Path Restoration and Performance Evaluation
•Comparison
•Simulation
•Conclusion
•Reference
1
Overview for MPLS
Operations of MPLS network(1)
Routing info(EX:OSPF)
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Source
LER
LSR
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Destination
(140.136/16)
Overview for MPLS(cont.)
Operations of MPLS network(2)
LDP using message protocol to build LSP
and save LIB
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Source
LER
LSR
LER
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Destination
(140.136/16)
FEC
Out label
In label
Out label
In label
Out label
140.136/16
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pop
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Overview for MPLS(cont.)
Operations of MPLS network(3)
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Ingress LSR
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Source
LER
LSR
FEC
Out label
140.136/16
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LER
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Destination
(140.136/16)
Overview for MPLS(cont.)
Operations of MPLS network(4)
-
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LER
LSR
LER
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Destination
(140.136/16)
In label
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Overview for MPLS(cont.)
Operations of MPLS network(5)
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Egress LSR
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140.136/16
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LER
LSR
LER
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Destination
(140.136/16)
In label
Out label
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POP
140.136/16
Overview for MPLS(cont.)
Operations of MPLS network(5)
Traditional IP Work
MPLS
Data flow(Packets)
Route Everyone
Route Once(Switch
Everyone)
Identifier
IP Address
Short and fixed label
To destination speed
Slow
Fast
QoS
Difficult to Support
Easy to Support
4
Overview for MPLS(cont.)
General Recovery Terminology(RFC 3469 at February 2003 in IETF)
• Re-routing
• Protection Switching
• Working Path(primary path and active path)
• Recovery Path (back-up path, alternative path,and protection path)
• Path Switch LSR (PSL)
• Path Merge LSR (PML)
• Fault Indication Signal (FIS)
• Fault Recovery Signal (FRS)
Hardware and Software Fault Tolerance
S. Yoon, H. Lee, D. Hhoi, Y. Kim, “ An Efficient Recovery
Mechanism for
MPLS-based Protection LSP”, IEEE, 2001.
5
Hardware and Software Fault Tolerance(Paper1)
IETF defined two recovery models-Protection switching
model and Rerouting model
１、Protection switching model
Disadvantage-does not make use of resources efficiently
Protection switching model
Hardware and Software Fault Tolerance(Paper1)
IETF defined two recovery models-Protection switching
model and Rerouting model
２、Rerouting model
(establishes recovery path after a fault occurs)
Disadvantage-takes a long recovery time,because the
LSR selects a recovery path and establishes it.
How to Improve ?
The pre-qualified recovery path
6
Hardware and Software Fault Tolerance(Paper1)
Hardware and Software Fault Tolerance(Paper1)
MPLS Recovery Cycle
• Fault Detection Time(T1)
-Time interval between the occurrence of the network impairment and the
moment the fault is first detected by an LSR
• Hold-off Time(T2)
-Waiting time between the detection of a fault and starting the recovery
action
• Notification Time(T3)
-Time between the initiation of a FIS by the LSR detecting a fault and the time
at PSL starts recovery operation
• Recovery Operation Time(T4)
-Time between the first and last last recovery actions
• Traffic Restoration Time(T5)
-Time between beginning to switch over to the recovery path and the arrival
time of the first restored traffic at PML
7
Hardware and Software Fault Tolerance(Paper1)
About pre-qualified recovery method in rerouting model
-When a failure occurs,the network state may differ from
the state of LSP setup time
-It may not maintain the optimal recovery path
considering the current network state
Hardware and Software Fault Tolerance(Paper1)
New pre-qualified mechanism
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Hardware and Software Fault Tolerance(Paper1)
Results for Proposed and Prequalified
Hosts(node 0,10,11) and LSRs(MPLS node 1-9).
Packet generation rate varies from 1Mb to 10Mb,packet size is 500bytes.
Link’s bandwidth is 10M and delay is 10ms.
6-10Mb(Proposed)
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0
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Break
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15Mb(Both)
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9
8
11
Protection LSP(LSR 1-4-6-9)
non-protection LSP(LSR 1-5-6-8-9,for increasing network traffic to N11 after the protection LSP setup)
Proposed LSP(LSR 4 -3-7-6)
backup path(LSR 4-5-6)
Hardware and Software Fault Tolerance(Paper1)
Results for Proposed and Prequalified
-Packet Loss
-Packet Reorder
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Hardware and Software Fault Tolerance
G. Ahn, and W. Chun, “Simulator for MPLS Path
Restoration and Performance
Evaluation”, IEEE, 2001.
Hardware and Software Fault Tolerance(Paper2)
-MPLS
• Combine flexibility of IP routing & efficiency of link-level
switching
-MPLS Path Protection/Restoration
• To provide a reliable service for traffic carried on MPLS
network
• To reroute traffic around a failure/congestion in a LSP
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Hardware and Software Fault Tolerance(Paper2)
- Protection configuration
• Dynamic protection
A backup path established after a failure detection on a
working path
• Pre-negotiated protection
A backup path established beforehand
- Repair activation
• Global repair
Protection activated on end-to-end basis (e.g, Ingress &
egress LSR)
• Local repair
Protection activated by each LSR that detects a failure
Hardware and Software Fault Tolerance(Paper2)
Three Schemes
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Hardware and Software Fault Tolerance(Paper2)
•Haskin
Hardware and Software Fault Tolerance(Paper2)
•Makam
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Hardware and Software Fault Tolerance(Paper2)
•Simple-Dynamic
Hardware and Software Fault Tolerance(Paper2)
•Simulator Architecture
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Hardware and Software Fault Tolerance(Paper2)
•LIB and ERB for LSR
Comparison
After
fault
Before
fault
Local
Global
1:1
Haski
n
*
Maka
m
Simple
Dyna
mic
*
*
*
Disadvantage
Support fast
reroute
Packet reordering
problem during the
switchover time
from BP to WP
after the recovery of
the failure
Almost no
packet
reordering
problem
Packet Loss
problem
Resource
utilization
Long LSP setup
time
*
*
*
Advantage
*
*
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Simulation
１、Simulaton(LSP Label Switching and delivering)
• Software :
Borland C++
•Topology and result after run :
Simulation(cont.)
１、Simulaton(LSP Label Switching and delivering)
• Source code(Part of MPLS.CPP) :
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Simulation(cont.)
２、Simulaton(Path restoration)
•Software :
Redhat Linux 7.2 + ns-2.1b8a
•Module:
mns_v2.0 for MPLS(classifier-addr-mpls.cc and h,ldp.cc
and h,mpls-module.cc and h)
•Topology :
•Node0,10 [$ns node]
•LSR1-9 [$ns mpls-node]
•Duplex-link $node $LSR
1Mb 10ms
•Attach-traffic $node0 $sink0
200Bytes 500kbit/s
Simulation(cont.)
２、Simulaton(Path restoration)
•TCL code(part):
$ns at 0.0 "record"
$ns at 0.3 "seq-record 200 500k
2.0"
$ns at 0.3 "$src0 start"
$ns rtmodel-at 0.8 down $LSR7
$ns rtmodel-at 1.3 up $LSR7
$ns at 1.8 "$src0 stop"
$ns at 2.0 "recv-pkts"
$ns at 2.0 "record"
$ns at 2.0 "finish"
$ns run
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Simulation(cont.)
２、Simulaton(Path restoration for haskin)
•Demo:
Simulation(cont.)
２、Simulaton(Path restoration for makam)
•Demo:
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Simulation(cont.)
２、Simulaton(Path restoration for Simple-Dynamic)
•Demo:
Simulation(cont.)
２、Simulaton Data Analysis and Evaluation
.Terms of Packet loss,reordering of packets, and
Resource utilization)
Packet loss
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Simulation(cont.)
２、Simulaton Data Analysis and Evaluation
.Terms of Packet loss,reordering of packets, and
Resource utilization)
Packet loss(Best Effort Traffic)
Packet Loss Comparison
400
Haskin
Makam
Simple-Dynamic
NB of Dropped packets
350
300
250
200
150
100
50
0
Node 3
NodeNode
5
Failed
Node 7
Simulation(cont.)
２、Simulaton Data Analysis and Evaluation
.Reordering of packets(Best Effort Traffic and Qos Traffic)
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Simulation(cont.)
２、Simulaton Data Analysis and Evaluation
.Packet loss(Qos Traffic) and Resource utilization
Conclusion
Performance evaluation
•Haskin’s scheme : fast rerouting, but packet reordering
problem.
•Makam’s scheme : no reordering problem, but packet loss
problem
•Simple-dynamic:high resource utilization, but packet loss
and reordering problem
•Packet reordering problem: may result in packet loss
problem in case of the reserved traffic
Future work
•Find another new path restoration scheme and simulate it
for performance issue.
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Reference
1.V.Sharma, F.HellstrandAndersson, , “Framework for MultiProtocol Label Switching (MPLS)-based Recovery”, RFC 3469,
February 2003.
2. Rosen, A. Viswanathan, and R. Callon, “Multiprotocol Label
Switching Architecture,” RFC 3031, January 2001.
3. S. Yoon, H. Lee, D. Hhoi, Y. Kim, “An Efficient Recovery
Mechanism for MPLS-based Protection LSP”, IEEE, 2001.
4.G. Ahn, and W. Chun, “Simulator for MPLS Path Restoration and
Performance Evaluation”, IEEE, 2001.
5.G. Ahn, and W. Chun, “Design and Implementation of MPLS
Network Simulator Supporting LDP and CR-LDP”, IEEE, 2000.
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