multi-protocol lambda switching for packet, lambda, and fiber...
TRANSCRIPT
Multi-Protocol Lambda Switchingfor Packet, Lambda, and Fiber Network
Jun Kyun Choi
Tel) (042) 866-6122
Contentsr Backgrounds for Optical Network
l Review of SONET/SDH Technologiesl Motivations for IP over WDMl Physical Limitation for Optical Internet
r Optical Switching Technologiesr Protocol Reference Model for Optical Internetr Architectural Model for Optical Networkr Control Plane for Optical Networkingr IP-based Optical Control Plane Issuesr Generalized MPLS & Optical User Network Interface
Signalingr Conclusions
Backgrounds for Optical Network - 1r Transform functionality of SONET/SDH to optical layerr Dynamic allocation for DWDM network capacity r Just-in-time provisioning for Dynamic Re-configurable
Optical Networkr Innovation and advances in optical components and
transport technologiesl Optical technology changing rapidlyl Optical device latency and synchronizationl Increased focus between electrical and optical devices
r Optical Multiplexing Schemesl WDM, OTDM, Optical CDMAl Underline frame structure (PDH, SDH, Digital Wrapper, MPLS, GbE
etc.)
Backgrounds for Optical Network - 2
r Re-evaluation of traditional network platforms and cost structuresl Service delivery requirements changing
l (e.g., 50 ms restoration time, reliability, etc.)
l Growing demand on OC-48c/OC-192c routers
r Limitations of existing architecturel Existing SONET/SDH ring-based architecture failingl Optimized for voice, Can’t scale enough for data
Motivation for Optical Networking
r Cost and Efficienciesl Waves cheaper than switching packetsl Eliminates costly O/E/O conversions and equipments
r Flexibility and Managementl Just-in-time service provisioning ?l Traffic engineering at the wave level ?
r Revenue Opportunitiesl Fast provisioned wave servicesl Bursty IP services through backbone network
Reviews of SONET/SDH Technologiesr Mature Technology → Too expensive, Over estimated, not
proper more than 2.5 Gbps, scalability problemr Multiplexing, Switching and Grooming → useful for existing
digital hierarchyr Self-Healing Capability → less effectiver High Availability and Extensive Management Capability →
No effective compared with othersr Limitations of SONET/SDH Ring
l Rings inefficient for large pipes l End-to-end provisioning, management, and protection
l Meshes are more efficient
Motivations for IP over WDMr Tremendous growth in data trafficl Router interfaces for OC-48c and OC-192c
r Elimination of SONET/SDH equipmentsr Pros and Cons of IP over WDMl Pros
l Protocol Independent, Efficiency-Overheadl Suitable for Applications with Large Volumes
l Consl Not Suitable for High Error Environmentsl Unable to Guaranteed Performancel No Gain of Bandwidth Efficiency for Bursty Trafficl Not Suitable for Low Speed Links
On-going Issues for IP over WDM
r Restoration and protectionr Performance monitoringr Fault isolationr Network engineering and bandwidth distributionr Wavelength managementr Network scalabilityr Adopting new transmission technologies
Physical Limitation for Optical Internet - 1
r Limitations of Optical Devicesl No optical buffering (not a delay line)l No optical processing
r Limitations of Optical WDMl Large bandwidth on single wavelengthl Long latency time for Wavelength tuning and conversion
r Limitations of Optical Switchl Large bandwidth on single fiberl Relative small size of optical switch (e.g. 256 x 256)l Long latency time for Switching-over
Optical Switching Technologies - 1
r Possible Architecturesl Lambda Switching with dynamic Re-configurationl Optical Burst Switchingl Optical Tag or Packet Switching
Optical Packet Switch
Optical Tag Switch
MPLS Switch
In-band Signalling
On-Line ControlOff-Line Control
Classifications
Lambda SwitchLambda-XCLambda Level
Optical Burst Switch
SDH-XCPath Level
VP SwitchVP-XCVirtual Level
Out-of-BandSignalling
Optical Switching Technologies - 2
r Pros/Consl Large BW with loose control capabilitiesl Suitable for large volume traffic with traffic aggregationl No traffic engineering in Lambda level → Single QoS for a
lambda, No flow control and No contention resolution
r Supports migration to mesh networksl Virtual level protectionl Scaled services: protected, unprotected, ...
Routing and Signalling Network
OpticalLayer
WDMLayer
IPLayer
RWASignalling
MPLSSignalling
IPSignalling
(SIP,etc)
C-plane
M-plane
U-plane
Optical
Link
Man
agem
ent
WDM
Man
agem
ent
Traffi
c, Flo
w
QoS
Man
agem
ent
IP R
outing
Protocol Reference Model for Optical Internet
OpticalLayer
WDMLayer
IPLayer
RWASignalling
MPLSSignalling
IPSignalling
(SIP,etc)
C-plane
M-plane
U-plane
Optical
Link
Man
agem
ent
WDM
Man
agem
ent
Traffi
c, Flo
w
QoS
Man
agem
ent
IP R
outing
OpticalLayer
WDMLayer
IPLayer
RWASignalling
MPLSSignalling
IPSignalling
(SIP,etc)
C-plane
M-plane
U-plane
Optical
Link
Man
agem
ent
WDM
Man
agem
ent
Traffi
c, Flo
w
QoS
Man
agem
ent
IP R
outing
Telecommunication Management Network
CoreRouter
EdgeRouter
EdgeRouter
Architectural Model for Optical Network
r Overlay Modell Separate the control plane between Optical Transport
Network (OTN) domains and IP domains
r Integrated (or Peer) Modell Same control plane in the OTN and IP domains
Evolution Model for Optical Internet - 1
ElectricRouter
EdgeNode
EdgeNode
EdgeNode
EdgeNodeOptical
(SDH/DWDM)
Optical(SDH/DWDM)
EdgeRouter
orNode
OpticalLT
CoreRouter
OpticalCross-
Connect
EdgeRouter
orNode
OpticalLT
Optical(DWDM)
EdgeRouter
orNode
OpticalLT
CoreRouter
WDMCross-
Connectwith/without
wavelength Converter
EdgeRouter
orNode
OpticalLT
OpticalTag
Switch
Core/Edge
Router
Core/Edge
Router
Core/Edge
Router
Core/Edge
RouterOptical
(DWDM)
OpticalOptical
Inte
grat
ed M
odel
Ove
rlay
Mod
el
WDM Switch
Evolution Model for Optical Internet - 2
Optical
EdgeRouter
orNode
OpticalLT
ElectricalCore
Router
Multi-StageWDMSwitch
EdgeRouter
orNode
OpticalLT
OpticalPacketSwitch
Core/Edge
Router
Core/Edge
Router
Core/Edge
Router
Core/Edge
RouterOptical
Optical
Core/Edge
Router
OpticalLT
OpticalPacketSwitch
Multi-StageFiber
Switch
Core/Edge
Router
OpticalLT
Optical
Inte
grat
ed M
odel
Ove
rlay
Mod
el
Evolution Stage - 1r 1st Stage (IP over static WDM)
l Utilize Large Bandwidth of Optical Device by Traffic Aggregationl Utilize Controllability and Manageability of Electronic IP Domainl Examples
l User interface: IP over static WDMl Access and Core: WDM-XC and Optical Fiber Switch by configuration at
set-up time
r 2nd Stage (IP over Dynamic WDM, Dynamic WDM-XC)l Reduce latency of wavelength tuning and conversion time l Reduce latency of Switching Over time l Examples
l User interface: IP over static or dynamic WDMl Access and Core: WDM-XC and Optical Fiber Switch by dynamic
reconfiguration
Evolution Stage - 2r 3rd Stage (Optical Tag Switch or Optical Burst Switch)
l Limited Optical Header Processing for framing and switchingl Optical Switch tightly coupled with electric control logicl Examples
l User interface: IP over dynamic WDM with variable-size message flowl Access and Core: WDM-XC and Optical Fiber Switch by on-line and on-
demand control(note) on-line control is classified into in-band and out-of-band signalling(note) Optical Burst Switching is out-of-band signalling without header processing.
Instead, it utilizes electric control signals to synchronize optical signals for switching
r 4th Stage (Optical Packet Switch)l Optical Header Processing with small latency timel Examples
l User interface: IP over dynamic WDM with fixed-size packetl Access and Core: Optical Packet Switch by on-line and on-demand control
Control Plane for Optical Networking - 1r Control Requirements
l Cost-effective OAMl Fault isolation and performance monitoringl Protection and restoration
l Rapid service provisioning for negotiated bandwidth and QoSl Scalability on bandwidth provisioning l Grooming of sub-rate circuitsl Dynamic Optical VPN according to SLAl Automatic configuration and topology auto-discovery
r Intelligence of Optical Networkingl Done by controllability
l Traffic control, Resource Control (Bandwidth, Lambda, Buffer), QoS, Signalling, VPN, etc.
l Node, Link and Path protection mechanism
Control Plane for Optical Networking - 2r Dynamic Reconfiguration of Optical Network
l Link Protection, Capacity Planning, Load distribution, etc.
r Integrated L1, L2 and L3 forwarding Enginel Switching/Routing, class (e.g., FEC), priority, etc.
r Traffic control and Traffic aggregationl Based on application, flow, class, lambda
r Optical VPN for multicast and securityr Multiple Access scheme for shared media (PON, etc)r Naming and addressing both for Optical switching and IP
routing
Control Plane for Optical Networking - 3
r Generic Requirements for OXC Control Planel Establish optical channel trails expeditiouslyl Support traffic engineering functionsl Support various protection and restoration schemes
r MPLS Traffic Engineering Control Planel Resource discoveryl State information disseminationl Path selection and Path management
IP-based Optical Control Plane Issues - 1
r Addressingl Identifiable entity
l OXC, optical link, optical channel, sub-channell SRLG (Shared Risk Link Group)
− An identifier assigned to a group of optical links that share a physical resource
1:OC48 5:OC192
2:OC48 6:OC192
3:OC48 7:OC48
4:OC192 8:OC48
OXC1OXC1 OXC2OXC2 OXC3OXC3
OXC4OXC4 OXC5OXC5 OXC6OXC6
IP-based Optical Control Plane Issues - 2
r Neighbor Discoveryl Discovery of local link statusl NDP (Neighbor Discovery Protocol)
l Determine the parameters between adjacent OXCs− Up/down status of each optical link− Bandwidth and other parameters of the link− Identity of the remote link (e.g., remote port number)
l Link management and fault isolationl Require in-band communication on the bearer channelsl Determine local connectivity and link status
IP-based Optical Control Plane Issues - 3
r Topology Discoveryl Procedure of determination the topology and resource state
of all the links in a sub networkl Using a link state routing protocol or management protocoll In optical links,
l Link state information − May consist of link bundles, Each link bundle is an abstract link in the
network topology− Capture restoration-related parameters for optical links
l Maintenance a single routing adjacency between neighborsl Flexibly updates link state owing to dynamic change of link
availability information
IP-based Optical Control Plane Issues - 4r Restoration Models
l Local mechanisml Select an alternate link between two adjacent OXCs when a failure affects
the primary link
l End-to-end mechanisml Pre-computed alternate pathsl “1+1” protection
− Establish a back-up path for the protected primary path along a physically diverse route. Both paths are active.
− The failure along the primary path à immediate switch-over to the back-up path
l Shared protection− Back-up paths share the same network resources
− When a failure affects a primary path, the same failure don’t affect the other paths whose back-ups share resources.
IP-based Optical Control Plane Issues - 5
r Signaling Issuesl Bi-directional Light path Establishment
l Output port for the forward direction at an OXC = input port for the reverse direction of the path
l Collision detection− The involved paths may be torn down and re-established.− Or, collisions may be avoided altogether.
l Failure Recoveryl When failures occur, a backup processor or a backup control channel
will be activated.l During failure recovery, desirable to recover local state at the
concerned OXC with least disruption to existing optical paths.
IP-based Optical Control Plane Issues - 6
r Optical Internetworkingl Should dynamically provision and restore light paths across
optical sub-networksl Requirements
l Uniquely identify light path end-points in different sub-networkl Protocol for determining reachability of end-points across sub-netsl Signaling protocol for provisioning light paths across sub-netsl Procedure for the restoration of light paths across sub-nets.
Generalized MPLS &Optical User Network Interface Signaling
Generalized MPLS - Signaling Functional Description
<draft-ietf-mpls-generalized-signaling-00.txt>
Signaling Requirements at the Optical UNI
<draft-bala-mpls-optical-uni-signaling-01.txt>
Network Service Modelr Domain Service Model
l Services defined by layered domainl Client/Server domain relationship
l IP is a client of the optical domainl Optical layer provides point-to-point
channels for clients
r Unified Service Modell A single integrated control plane structure
l single signaling and routing protocol
l MPLS-based optical networkl IP signaling and routing protocols need to
be modified to support optical characteristics
Source : Source : TelliumTellium
MPLS-Based Approach for Optical Internet – 1
r IP-based approaches for rapid provisioningl Re-use existing signaling frameworkl Less standardization, faster vendor interoperabilityl No addressing concerns arise (use IP addresses)
r Key MPLS features exploitedl Hierarchical LSP tunneling (label stacking/swapping)l Explicit routing capabilitiesl LSP survivability capabilitiesl Constraint-based routing
MPLS-Based Approach for Optical Internet – 2
r Traffic Engineering in Optical Networkl Optical network load balancingl Performance optimizationl Resource utilization optimization
r Requires Dynamic Control Mechanisml Network state monitoringl Feedback control
l Routing parameters, Resource parameters, Traffic management parameters, etc.
Integrated Control Plane for Optical Internet - 1
r Extensions to MPLS signaling l Encompass time-division (e.g. SONET ADMs), wavelength
(optical lambdas) and spatial switching (e.g. incoming port or fiber to outgoing port or fiber)
l Label is encoded as a time slot, wavelength, or a position in the physical space
l Bandwidth allocation performed in discrete units.
Integrated Control Plane for Optical Internet - 2
r Supports Multiple Types of Switchingl Support for TDM, lambda, and fiber (port) switchingl OXC (Optical Cross-Connect) can switch an optical data
stream on an input port to a output portl A control-plane processor that implements signaling and
routing protocol
r Optical Mesh Sub-Networkl A net. of OXCs that supports end-to-end networkingl Provide functionality like routing, monitoring, grooming and
protection and restoration of optical channels
Forwarding Interface of GMPLSr Packet-Switch Capable (PSC)
l Recognize packet/cell boundaries and forward data based on header.r Time-Division Multiplex Capable (TDM)
l Forward data based on the data’s time slot in a repeating cycle.r Lambda Switch Capable (LSC)
l Forward data based on the wavelengthr Fiber-Switch Capable (FSC)
l Forward data based on a position of the data in the real physical spaces.
PSCPSC TDMTDM LSCLSC FSCFSC
Allow the system to scale by building a forwarding Hierarchy
Client – Optical Interface Model - 1
r Direct Interface• IPCC(IP control channel)
• -exchanging signaling and routing messages between the router andthe OXC
• Edge router and the OXC are peers in the control plane• Example routing protocol - OSPF/ISIS or BGP• Example signaling protocol - RSVP-TE or CR-LDP
Edge RouterEdge Router
Routing Routing ProtocolProtocol
SignalingSignalingProtocolProtocol
IP LayerIP Layer IPCCIPCC
OXCOXC
Routing Routing ProtocolProtocol
SignalingSignalingProtocolProtocol
IP LayerIP Layer
Client – Optical Interface Model - 2
r Indirect Interface• Out-of-band IP control channel
l Between the client and optical network elements, in case that the OXCs and/or clients don’t support a direct interface
r Provisioned Interfacel Manually provisioned by Network Operatorl No control interfaces between edge router and the optical
network
Generalized Label Requestr Generalized label contains information to program cross connect
r Supports communication of characteristic to support the LSP
r Include link protection, LSP encoding, and LSP payloadl LSP Encoding Type indicates the encoding of the LSP l Link Protection Flags indicates the desired protection levell Generalized PID is the identifier of the payload carried by an LSP.
r LSR must verify that the request parameters can be satisfiedr If node cannot support, the node must generate a Notification message
l “Routing problem/Unsupported Encoding”l “Routing problem/Unsupported Link Protection”l “Routing problem/Unsupported G-PID”
Generalized Labelr Carry a label that represents
l A single fiber in a bundlel A single waveband within fiberl A single wavelength within a wavebandl A set of time-slots within a wavelength
v Label : Variable (depends on the type of the link)
Suggested Label r Used to provide a downstream node with the upstream
node’s preference
r Upstream node configures it’s hardware with the proposed label before the label is received by the downstream node
r Reduce setup latency
q CR-LDP
q With extensions
q Downstream LSR can ignore label suggestion
∼∼∼ ∼∼∼ ∼∼∼ ∼∼∼Label RequestLabel Request
LabelLabel
Label RequestLabel Request
LabelLabel
Label RequestLabel Request
LabelLabel
∼∼∼ ∼∼∼ ∼∼∼ ∼∼∼Suggested LabelSuggested Label
LabelLabel
Suggested LabelSuggested Label
LabelLabel
Suggested LabelSuggested Label
LabelLabelSource : Source : ChromisysChromisys
q LDP
q With extensions
∼∼∼ ∼∼∼ ∼∼∼ ∼∼∼
Label RequestLabel Request
LabelLabel
Label RequestLabel Request Label RequestLabel Request
LabelLabel LabelLabel
Label RequestLabel RequestLabel RequestLabel RequestLabel RequestLabel Request
LabelLabelLabelLabelLabelLabel
∼∼∼ ∼∼∼ ∼∼∼ ∼∼∼
Upstream Label,Upstream Label,Suggested LabelSuggested Label
LabelLabel
Upstream Label,Upstream Label,Suggested LabelSuggested Label
Upstream Label,Upstream Label,Suggested LabelSuggested Label
LabelLabel LabelLabel
Source : Source : ChromisysChromisys
q Reduces trail establishment latency
q Increases success probability
Bi-directional LSP establishment
Physical Control Structure of O-UNI
ONE: Optical Network ElementISI: Internal Signaling InterfaceND: UNI neighbor discovery
Optical Network
ND UNI
ND UNI
ONE ND
UNI
UNI-N
UNI-N UNI-N
UNI-NInternal Connectivity
UNI
ND
UNI-C
client ONE
UNI-C
client
UNI-C
client
UNI-C
client
Optical Network
ND
UNI
ONE
UNI
ND
ND
UNI
ND
UNI
ISI
ISI
UNI-C
client
UNI-C
UNI-C UNI-C
UNI-N
Internal Connectivity
ONE
ND
ND
ND
UNIISI
UNI
UNI
ISI
ISI
ND
Optical Network
ONE
UNI-N
UNI-N UNI-N
UNI-NInternal
Connectivity
client ONE
UNI-C
Client Network
ISI
client
UNI-C
UNI-C
ND
ND
NDND
UNIUNI
Optical Network
ONE
ISI
ISI
UNI-N
Internal Connectivit
y ONE
ISI
client
UNI-CISI
client
UNI-C
UNI
ISIISI
Client Network
UNI-C
•Direct Interface •Indirect Interface : Client to Optical Network Management Agent
•Indirect Interface :Client Agent to ONE •Indirect Interface :Client Agent to Optical Network Management
UNI Signaling Messager Lightpath Create Requestr Lightpath Create Responser Lightpath Delete Requestr Lightpath Delete Responser Lightpath Modification Requestr Lightpath Modification Responser Lightpath Status Enquiryr Lightpath Status Responser Notification r Address Query
UNI Message Parameter (1/2)r Identification
l Lightpath ID : A network unique identifier for a lightpathl Contact ID : A carrier-assigned identification to identify the service contractl Source/destination client point of attachment : Optical network administered IP address
and logical port information l User group ID : VPN identifierl UNI-C ID : IP address of the UNI-C entity
r Service-Relatedl Directionality : Uni-directional or bi-directionall Framing type : Format of the signal to be transported across the UNIl Overhead termination type : Specifies to what degree the framing overhead bytes are
terminated for SONET and SDH framing.l Bandwidth : The bandwidth of the service.l Propagation delay : Maximum acceptable propagation delay. l Service level : An integer specifying the service level requested for the lightpath
UNI Message Parameter (2/2)r Routing-related
l Diversity : A list of n lightpaths from which the present lightpath must be physically diverse in the network.
r Miscellaneousl Result Code : Indicates success or failure of certain operationl Status : Indicates the status of a lightpath
r Security-relatedr Policy, accounting and authorization related
LDP Extensions for O-UNI signalingr Applying LDP at the O-UNI allows for :
l The reuse of already defined LDP message and message formatsl The reuse of LDP session management and control proceduresl Additions to the already specified procedures for notification of errorsl The reuse of the LDP security mechanism
r The addition of new TLVs to support the attributes required for lightpath establishment at the O-UNI
r Two new LDP messages to allow for the exchange of lightpathstatus information across the UNI
O-UNI Session Management and Controlr Hello Message
l Use the format and the procedures of the LDP Hello Message
r KeepAlive Messagel Use the format and the procedures of the LDP KeepAlive Message
r Initialization Messagel The Label Advertisement Discipline is always set at 1 to indicate
Downstream on Demand label distribution mode.
l Loop Detection is always disable, D = 0.
Use of LDP Messages for O-UNI (1/2)r Lightpath Create Action
l Lightpath Create Request : achieved by the LDP Label Request Message and Generalized Label Request TLV
l Lightpath Create Response : achieved by the LDP Label Mapping Message and Generalized label
r Lightpath Delete Actionl Lightpath Delete Request : achieved by the LDP Label Release Request
Message.l Lightpath Delete Response : achieved by the LDP Label Withdraw
Message
Use of LDP Messages for O-UNI (2/2)r Lightpath Modify Action
l After a lightpath is setup, some of its attributes may need to be changed by the network operator
l Does not require the definition of new LDP messagel Use the Action Flag (ActFlg) field in the Lightpath Id TLV in the
Lightpath Create Request Message.
r Lightpath Status Actionl Lightpath Status Enquiry Message : solicit a Status Response Message
from its peer.l Lightpath Status Response Message : The Status TLV carries
information that describes the current status of lightpath.
r Notification Actionl The LDP Notification message is used across the O-UNI
Conclusionsr Architectural Evolution for Optical Networkl Single Control Plane Both for IP domain and Optical
Domainl IP-centric control mechanisms are being used for optical
layer controlr MPλS Technologiesl Extends MPLS to encompass time-division, wavelength and
spatial switchingl Adapt IP Traffics to Physical limitations of Optical
Technologiesl Generalized MPLS is used both for Unified Service Model
and Domain Service Model
Referencesr B. Rajagopalan et. al, "IP over Optical Networks: A Framework", <draft-many-ip-
optical-framework-02.txt>, November, 2000.r Daniel O. Awduche et. al, “Multi-Protocol Lambda Switching : Combining MPLS
Traffic Engineering Control with Optical Crossconnects”, <draft-awduche-mpls-te-optical-02.txt>, July, 2000
r P. Ashwood-Smith et. al, "Generalized MPLS – Signaling Functional Description", <draft-ietf-mpls-generalized-signaling-00.txt>, Internet Draft, November, 2000.
r Peter Ashwood-Smith et. al, “Generalized MPLS Signaling – CR-LDP Extensions”, <draft-ietf-mpls-generalized-cr-ldp-00.txt>, November, 2000
r Osama S. Aboul-Magd et. al. “Signaling Requirement at the Optical UNI”, <draft-bala-mpls-optical-uni-sigaling-01.txt>, October, 2000
r Osama S. Aboul-Magd et.al. “LDP Extensions for Optical User Network Interface (O-UNI) Signaling”, <draft-ietf-mpls-ldp-optical-uni-00.txt>, October, 2000
r Jamoussi et al., "Constraint-Based LSP Setup using LDP", <draft-ietf-mpls-cr-ldp-04.txt>, July, 2000.
r Andersson et al., "LDP Specification", <draft-ietf-mpls-ldp-11.txt>, August 2000.