RSVP-TE Extensions for LSP Rerouting in NS2 - Communication

20 Pages·2007·1.25 MB·English

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
1 Michele Pagano
Outline
• Introduction
• MPLS-based Recovery
• RSVP-TE Reservation Styles
• NS2 Software Modules
• Simulations Results
• Conclusions
2 Michele Pagano
Introduction
• Multiprotocol Label Switching (MPLS) provides:
(cid:57) Traffic Engineering capabilities
(cid:57) Virtual Private Networks support
(cid:57) Network Survivability
EEggrreessss LLSSRR ((LLaabbeell ppooppppiinngg))
TTrraannssiitt LLSSRR ((LLaabbeell sswwaappppiinngg))
IInnggrreessss LLSSRR ((LLaabbeell ppuusshhiinngg)) In In Address Out Out
In In Address Out Out
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 ... ... ... ... ...
... ... ... ... ...
LLSSRR BB
40 172.16.1.2 data 172.16.0.0/16
LLSSRR AA
LLSSRRCC
30 172.16.1.2 data
172.58.0.0/16
172.16.1.2 data
172.16.1.2 data
3 Michele Pagano
IP Routing
R8
R1
R3
R4
R2
Shortest
Path
LSR8
R5
R9
R7 R6
High Convergence Time!
IIssssuueess
(cid:57)Highly reliable services require very low recovery times (tenths of ms)
(cid:57)IP routing does not assure QoS recovery
4 Michele Pagano
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!
5 Michele Pagano
MPLS Recovery: Path Restoration
Egress
LER
LSR1
LSR3
LSR4
LSR2
LSR8
LSR5
Ingress
LER
LSR7 LSR6
MMPPLLSS--bbaasseedd RReeccoovveerryy OObbjjeeccttiivveess
(cid:57)Optimal use of network resources
Working LSP
(cid:57)Traffic protection with different granularity
Backup Path
(cid:57)Minimization of unprotected traffic degradation
6 Michele Pagano
The Recovery Cycle
Egress
LSR1 Resv
LER
LSR3
LSR4
LSR2
PathErr
PathTear
LSR8
LSR5
Ingress
LER
LSR7 LSR6
Path
RReeccoovveerryy
FFaauulltt DDeetteeccttiioonn FFaauulltt HHoolldd--ooffff FFaauulltt NNoottiiffiiccaattiioonn OOppeerraattiioonn TTrraaffffiiccRReeccoovveerryy
TTiimmee TTiimmee TTiimmee TTiimmee TTiimmee
Start of Recovery Path
Network Fault Start of
Recovery Operation Traffic
Impairment Detected Notification
Operation Complete Recovered
7 Michele Pagano
RSVP-TE Reservation Styles
Distinct Reservation Shared Reservation
Explicit Sender Fixed-Filter Shared-Explicit
Selection
(FF) style (SE) style
Wildcard Sender Wildcard-Filter
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
8 Michele Pagano
RSVP-TE Reservation Styles: Application Scenario
B C
(2,100)
LSP (A_B_C_F) (1,50) (1,100)
40 Mbps A F
(1,100) (2,100)
(1,50)
Bandwidth
(1,100) (1,50)
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
9 Michele Pagano
Motivations and targets
• Since planning MPLS-based recovery strategies involves trade-offs
based on several factors
(cid:57) End-user applications requirements
(cid:57) Network efficiency
(cid:57) Complexity
(cid:57) 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)
(cid:57) developed at Chungnam National University, Korea
(cid:57) based on the Constrained Routing – Label Distribution Protocol (CR-LDP)
but…a full open-source MPLS networks simulation tool had not been
realized yet!!
10 Michele Pagano