Routing in Multi-Layer Transport Networks · Routing in Multi-Layer Transport Networks Jonathan...
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ITU-T Workshop “NGN and its Transport Networks“ Kobe, 20-21 April 2006 International Telecommunication Union ITU-T Routing in Multi Routing in Multi - - Layer Layer Transport Networks Transport Networks Jonathan Sadler Office of the CTO – Technology Strategy, Tellabs Chair, OIF Architecture & Signaling Working Group SG15 Special Representative to IETF for Routing
Transcript of Routing in Multi-Layer Transport Networks · Routing in Multi-Layer Transport Networks Jonathan...
ITU-T Workshop “NGN and its Transport Networks“Kobe, 20-21 April 2006
International Telecommunication UnionITU-T
Routing in MultiRouting in Multi--LayerLayerTransport NetworksTransport Networks
Jonathan SadlerOffice of the CTO – Technology Strategy, Tellabs
Chair, OIF Architecture & Signaling Working GroupSG15 Special Representative to IETF for Routing
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Agenda
o Service-based routingo ASON Multi-layer Routing Architectureo Remote Path Computation
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Discussion of Convergence is Everywhere
o “…the access infrastructure telcos are building to support IPTV services will finally give them the ability to converge voice, video and data onto a single network…”– Americas Network
o Pseudo-Wires are “the solution for convergence in future telecom networks, because it preserves profitable legacy services even as it enables the creation of a truly next-generation network” – Heavy Reading
o “3GPP defines a new subsystem to enable the convergence of voice and data applications and the harmonization of various mobile network technologies over IP”– Deutsche Bank
Convergence is changingthe face of the network
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The Benefits of Convergence
o Services reduced to applications on converged infrastructure• Reduced operations• Reduced core cap-ex
o New services can be provided• Individual Networks per Service limited service interaction
o Packet & optical routing convergence can improve network performance even if only IP services are provided
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The Reality of Convergence
o Non-native service delivery• End User Services are always layered on something else
o The whole network will not be converged overnight• Too many existing services already deployed
o The whole network will never be completely converged• Fully depreciated equipment still generates revenue
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How Can This Be Accommodated?
o Common flexible control method that understands layering• Path Computation that understand layered networks
—Provides service routing given view of potential/available server layer resources
• Signaling mechanisms that coordinate calls in different layers• OSSes that can handle integrated views of layer networks
—Relate services requests (client layer calls) to server resources in use
• Definitions for server layer resources other than SONET/SDH
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Access A
Access B
Core
CPE-A
CPE-B
The Network is Segmented
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CPE-A
CPE-B
Different Organizations Manage Different Parts of the Network
Access A
Access B
Core
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CPE-A
CPE-B
Provisioning Service is expensive and time consuming
We will fill your order
within 3 months
I forgot that we ordered this service!
Access A
Access B
Core
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CPE-A
CPE-B
Control Plane Speeds it upAccess A
Access B
Core
Sure, we’re setting your
service up as we speak
Wow, that was fast!
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CPE-A
CPE-B
Will use of different technologies cause
the problem to reoccur?
Access A(Ethernet)
Access B(SONET/SDH)
Core(MPLS Pseudo Wire)
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ITU-T Ethernet NetworkGE/NNI
BPON
OCN/NNI
GE/NNI
GE/UNI
T1, T3, OCNUNI
GE/NNI
10/100
BPON
10/100
T1, T3, OCNUNI
GE/NNI
STS1 Network*OCN/NNI
OCN/NNI
nxT1
OCN/NNI
OCN/NNI
GE/UNI
T1, T3, OCNUNI or Null
OCN/NNI
10/100
nxT1
GE/MPLS
10/100 T1, T3, OCNUNI or Null OCN/NNI
MPLS Network*
OCNUNI
OCNUNI
BPON
CPE-B
Access A(Ethernet)
Access B(SONET/SDH)
Core(MPLS Pseudo Wire)
It doesn’t have to…
CPE-A
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ITU-T Ethernet NetworkGE/NNI
BPON
OCN/NNI
GE/NNI
GE/UNI
T1, T3, OCNUNI
GE/NNI
10/100
BPON
10/100
T1, T3, OCNUNI
GE/NNI
STS1 Network*OCN/NNI
OCN/NNI
nxT1
OCN/NNI
OCN/NNI
GE/UNI
T1, T3, OCNUNI or Null
OCN/NNI
10/100
nxT1
GE/MPLS
10/100 T1, T3, OCNUNI or Null OCN/NNI
End-to-end SignaledService Provisioning!
Sure, we’re setting your
service up as we speak
Wow, that was fast!
MPLS Network*
OCNUNI
OCNUNI
BPON
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ASON MultiASON Multi--layer Routing layer Routing ArchitectureArchitecture
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Multi-layer overview
o Need path computation for a network made up of many different technologies, in any layer that has switching flexibility.
o Current methods separate network topologies per technology, creating separate discontinuous graphs
o Path Computation methods only operate on graphs without discontinuity.
Need to make a continuous routing view for a multi-technology network
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Representation of Server Layer connectivity
o G.8080 (2006): Two major approaches, with two minor forms:• Server Layer Representation using Links only:
— Client layer links resulting from established server layer trailso Result of cross connection of fibers, HOVC paths, etc.
— Client layer links provided by potential server layer trailso Abstract links representing potential connectivityo Requires management specification
• Server Layer Representation using Links & Subnetworks— Client layer abstract node containing server layer
o Abstract topology representing potential connectivityo Can be generated automatically
— Server layer topology shadow in client layero Non-abstract topology showing server links incl. attributeso Can be generated automatically
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o Connection is established in Server Layero Link appears in Client Layer
Representation using client links (actual)
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o Link is put into client layer knowing that server layer resources exist
o Server layer trail is established when link is put into use
Representation using client links (potential)
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o Client layer is provided with an abstract node that represents the server layer connectivity• Routing can compute a path in the client layer
o Server layer connection established when abstract node appears in client layer ERO
Representation using client subnetwork
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o Client layer contains server layer topologyo Routing can see all attributes of server layer resourceso Server layer connection established using client layer ERO
information
Representation using client subnet & links
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What information is required?
o Understanding of adaptations in useo Understanding of termination/switching capabilityo Ability to control choice of server layer trails in
place of client layer links
G.805
Policy
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What information is required?
o GMPLS Routing Announcements• Limited to switching capability information• Need to add adaptation and termination capability info
o Adding this information creates a “backward compatibility” problem• Similar to problem that exists between MPLS and GMPLS
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ASON Support forASON Support forRemote Path ComputationRemote Path Computation
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What is PCE?
o PCE = Path Computation Elemento Facilitated by ASON Functional Architecture
• Functional Architecture makes no assumptions onphysical location
o Essentially a remote procedure call method• Used within an area between Signaling (CC) and
Routing instances (RC)• Used between areas by routing instances (RC)
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o Enables end-to-end path computation without knowing the whole network topology• Source specified constraints are communicated• Path Computation performed on nodes with access to
topology• Provides support for inspecting interior of abstract nodes
What is PCE?Use of PCE in single technology areas
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Example of PCE interaction
LRM
CC
RCA1
A
RCA0
D
LRM
CC
RCA0
H
LRM
CC
RCA1
B
LRM
CC
RCA1
LRM
CC
RCA3
F
LRM
CC
RCA3
G
LRM
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RCA3
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ConnectionRequest
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RCA0
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LRM
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LRM
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RCA2
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RCA2
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Equipment NodeSubnetwork Routing Area
AB
C
EG
FI
RC-RC Route Query
L1
L2L3
L4 L5L6
DH
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A1
A2
A3
A0
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o If all nodes to support multi-layer control plane, need for PCE is limited to path computation for special constraints• Many network requests can be handled through ASON Source
Routing methods
o Nodes that don’t support multi-layer control plane can PCE to make up for inability to support new routing attributes
Use of PCE in mixed-technology areas
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Example of multi-technology PCE interaction
LRM
CC
RCA1
A
RCA0
D
LRM
CC
RCA0
H
LRM
CC
RCA1
B
LRM
CC
RCA1
LRM
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RCA3
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RCA3
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LRM
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RCA3
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ConnectionRequest
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RCA0
C
LRM
CC
LRM
CC
RCA2
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20 19
RCA2
RCA3
Equipment NodeSubnetwork Routing Area
AB
C
EG
FI
RC-RC Route Query
L1
L2L3
L4 L5L6
DH
G
A1
A2
A3
A0
WDMSDHSDH
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Conclusion
o Network continues to strive for convergence• Convergence technology chosen will be based on services
offered, causing different technologies to be used• Network will not be converged overnight
o New mechanisms defined in G.8080 to representmulti-layer networks allowing for path computation.
o Path Computation Elements provide a method for backward compatibility between single-layer and multi-layer capable nodes.
