Reliability Issues in IP over WDM Networks€¦ · Several Views for IP over WDM Networks SONET ATM...

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Advanced Network Architecture Research Advanced Network Architecture Research Reliability Issues in Reliability Issues in IP over WDM Networks IP over WDM Networks Masayuki Murata Graduate School of Engineering Science Osaka University e-mail: [email protected] http://www-ana.ics.es.osaka-u.ac.jp/~murata/ M. Murata 2 Advanced Network Architecture Research Advanced Network Architecture Research Past Researches in the Area oRouting and Wavelength Assignment (RWA) Problem 7 Static assignment 4Optimization problem 7 Dynamic assignment 4Natural extension of call routing 4Call blocking is primary concern 4No wavelength conversion makes the problem difficult oOptical Packet Switches for ATM 7 Fixed packets and synchronous transmission X X X Optical Cross-Connect Router

Transcript of Reliability Issues in IP over WDM Networks€¦ · Several Views for IP over WDM Networks SONET ATM...

Page 1: Reliability Issues in IP over WDM Networks€¦ · Several Views for IP over WDM Networks SONET ATM WDM IP oIP over ATM over SONET over WDM oIP over SONET over WDM oIP over (PPP or

AdvancedNetworkArchitectureResearch

AdvancedNetworkArchitectureResearch

Reliability Issues inReliability Issues inIP over WDM NetworksIP over WDM Networks

Masayuki MurataGraduate School of Engineering ScienceOsaka Universitye-mail: [email protected]://www-ana.ics.es.osaka-u.ac.jp/~murata/

M. Murata 2

AdvancedNetworkArchitectureResearch

AdvancedNetworkArchitectureResearch

Past Researches in the AreaoRouting and Wavelength Assignment (RWA)

Problem7 Static assignment

4Optimization problem

7 Dynamic assignment4Natural extension of call routing4Call blocking is primary concern4No wavelength conversion makes the problem difficult

oOptical Packet Switches for ATM7 Fixed packets and synchronous transmission

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Optical Cross-Connect

Router

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AdvancedNetworkArchitectureResearch

AdvancedNetworkArchitectureResearch

Several Views for IP over WDM Networks

SONETATM

WDM

IP

oIP over ATM over SONET over WDMoIP over SONET over WDMoIP over (PPP or HDLC) over WDM

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AdvancedNetworkArchitectureResearch

AdvancedNetworkArchitectureResearch

oFour Kinds of Architecture1. WDM link network

4Connects adjacent routers by WDM (multiple wavelengths)

2. WDM path network 4Logical topology is built

by wavelength routing

Photonic Internet Architecture

Router

Optical Crossconnect

Router

XX

XX

XX

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AdvancedNetworkArchitectureResearch

AdvancedNetworkArchitectureResearch

3. WDM Path Network4Lambda switching by

MPLS technology

4. WDM Packet-switched Network

4E.g., burst switching by routing and wavelength assignment on demand basis

Photonic Internet Architecture (Cont’d)

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Optical Cross-Connect

Router

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burst

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AdvancedNetworkArchitectureResearch

AdvancedNetworkArchitectureResearchWavelength Router

in WDM Path Network

OpticalSwitchOpticalSwitch

ElectronicRouter

ElectronicRouter

Wavelength Demux Wavelength Mux

Wavelength Router

OpticalSwitchOpticalSwitch

λ2

λ1

λ1

λ1

λ1

λ2λ2

λ2

λ2

λ2

λ1

λ1

λ2

λ1

Local Access

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AdvancedNetworkArchitectureResearch

AdvancedNetworkArchitectureResearch

Logical Topology by Wavelength Routing

oPhysical Topology oLogical Topology

Router

WDM Node

Wavelength

λ2 λ2λ1 λ1λ2

λ1

N3N2

N4N1

N5

λ2 λ2λ1 λ1λ2

λ1

N3N2

N4N1

N5λ1

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AdvancedNetworkArchitectureResearch

AdvancedNetworkArchitectureResearch

Logical View provided to IP

oRedundant Network with Large Degrees

åSmaller number of hop-counts between end-nodes

åDecrease load for packet forwarding at the router

åRelief bottleneck at the router

λ2λ1 λ1

λ1

λ1

λ2

N 3N2

N 4N1

N5

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AdvancedNetworkArchitectureResearch

AdvancedNetworkArchitectureResearch

How should IP over WDM be Established?

oWDM network itself has network control capabilities7 Routing function

4IP also has it!7 Congestion control function

4TCP also has it!4TCP over ATM (ABR service class) is difficult to work well

Parameter tuning of control parameters in ABR is not easy7 Connection establishment

4IP is connectionless4Multimedia application does not require 10Gbps channel

å Functional partitioning vs. Multi-layered Functionalities?

o Important is reliability

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AdvancedNetworkArchitectureResearch

AdvancedNetworkArchitectureResearch

Functional Partitioning between IP and WDM?

oReliability functionalities offered by two layers7 IP Layer: Routing7 WDM Layer: Path Protection and Restoration

oWDM should provide its high-reliability mechanism to IP7 Protection mechanism

4link protection4dedicated-path protection4shared-path protection

7 Network dimensioning is important to properly acquire the required capacity of IP paths (traffic glooming)

4Reconfiguration mechanism of logical topology by wavelength routing

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AdvancedNetworkArchitectureResearch

AdvancedNetworkArchitectureResearch

WDM Protectiono Immediately switch to backup path on failure of nodes/links

7 In the order of 10mso 1:1 Protection vs. Many:1 Protection

o Protection technique suitable to IP over WDM network?7 IP has its own protection mechanism (i.e., routing) while it

is slow7 We want an effective usage of wavelengths7 Many:1 protection is reasonable

1:1 Protection

Primary Path

Backup Path

Many:1 Protection

Primary Path

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AdvancedNetworkArchitectureResearch

AdvancedNetworkArchitectureResearchFormulation of Reliability Design

Problem for Many-to-1 Path Protection

oObjective7 Minimize the utilized wavelengths in total

oGiven Conditions7 The number of wavelengths on the fiber7 Physical topology and logical topology7 Primary routes

oApplication to 5-node network

N0

N3

N2N1

N4

N0

N3

N2N1

N4

Sharing of wavelengths

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AdvancedNetworkArchitectureResearch

Application to Large-Scaled Network

oPrevious formulation is MILP (Mixed Integer Linear Problem); difficult to be applied to the large-scaled network

oMin-hop-first approach7 It is rare that lightpaths with a small number of hop counts

contend the backup lightpaths7 First protect the lightpaths with small hop-counts, and

then protect lightpaths with large hop-counts using the remaining wavelengths

oLargest-traffic-first approach7 Assign the paths in a descending order of the traffic loads

oRandom approach7 For only reference purpose

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AdvancedNetworkArchitectureResearch

AdvancedNetworkArchitectureResearch

Network Model

oNSFNET; 7 14 node7 20 physical links

oLogical topology is first determined by MLDA7 First set up the lightpaths

between adjacent nodes7 Set up the lightpaths for the

path in a descending order of traffic volume NSFNET

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AdvancedNetworkArchitectureResearch

Effect of Min-Hop-First Approach

oThe required number of wavelengths to protect all lighpaths with 7 Random-selection

method?7 Traffic-large-first

method?7 Min-hop-first method?

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requ

ired

# o

f wav

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gths

# of primary wavelengths

min-hop-firsttraffic -first

random

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AdvancedNetworkArchitectureResearch

AdvancedNetworkArchitectureResearchEffect of Min-Hop-First Approach

(Cont’d)

oFix the wavelength on the fiber to be 16oChange the number of wavelengths dedicated to

primary lightpaths to compare the number of protected lightpaths

0

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perc

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random

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AdvancedNetworkArchitectureResearch

Effect on IP Routerso A increased amount of traffic load at the IP router after the

failure?7 We choose the largest traffic increase among all possible cases

for failureso Primary wavelengths; 12, Backup wavelengths; 4o Largest-traffic -first approach can decrease the traffic

handled by the IP router[Mpps]

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N 0 N 1 N 2 N 3 N 4 N 5 N 6 N 7 N 8 N 9 N 1 0 N 1 1 N 1 2 N 1 3

R a n d o m

M i n - h o p

L a r g e s t - t r a f f i c

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AdvancedNetworkArchitectureResearch

AdvancedNetworkArchitectureResearch

Functional Partitioning in IP over WDMo Total volume of the traffic protected/non-protected by

backup lightpaths before routing table upgradeo Sum of total traffic volume for each fiber failure scenarioo Largest-traffic -first approach provides better performance

7 Lots of traffic is protected by a lower number of backup wavelengths

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largest-trafficmin-hop

random-restoration

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olum

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Mpp

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# of primary wavelengths

largest-trafficmin-hoprandom

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AdvancedNetworkArchitectureResearch

AdvancedNetworkArchitectureResearch

Effect of IP Routing Table Updateo traffic volume of non-protected lightpath before/afterbefore/after routing table

upgrade o Largest-traffic-first approach also provides good performanceo Traffic volume increase after routing tables are updated

7 Another path is selected after update

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Mpp

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# of primary wavelengths

largest-trafficmin-hop

random-restoration

before upgrade

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fic V

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# of primary wavelengths

largest-trafficmin-hoprandom

after upgrade

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AdvancedNetworkArchitectureResearch

AdvancedNetworkArchitectureResearch

Concluding RemarksoWDM Protection is useful to increase

reliability of IP over WDM networksoA cost effective way must exist by

partially protecting lightpaths by WDM protection

oSeveral backup paths (8/182) are not used IP after IP updates its routing table.