1. Should I Migrate My MPLS-TE Network to GMPLS. And if so, how
Should I Migrate My MPLS-TE Network to GMPLS? And if so, how? Adrian Farrel Old Dog Consulting
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2. Questions, Only Questions
What is MPLS-TE?
What is GMPLS?
How does GMPLS differ from MPLS-TE?
How and why are protocols extended?
How do we achieve interoperability?
Why should we migrate and not extend?
What are the strategies for migration?
What should happen next?
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3. MPLS-TE Traffic engineering in MPLS packet networks
Place traffic to optimize network use
Reserve resources to guarantee QoS
Establish LSPs for protection and restoration
Need to know what network resources are available
Additions to IGP routing protocols (IS-IS and OSPF)
Distributes bandwidth availability with link state
Need to compute routes for LSPs
NMS, ingress LSR, or PCE
Need to signal for LSP establishment
RSVP-TE
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4. GMPLS Origins lie in control of WDM systems
MPλS
Labels are re-invented and wavelengths
Resources are implicit
Now extended to cover a variety of technologies
Fiber/port switching
Lambda switching (WDM, G.709 OTN)
Timeslot switching (TDM)
Layer 2 switching (Ethernet, ATM, Frame Relay, PBB)
Packet switching (MPLS, MPLS-TP)
A set of protocols (IS-IS, OSPF, RSVP-TE, LMP)
To distribute information about links and resources
To establish LSPs
To test and exchange information about data links
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5. How Different is GMPLS? GMPLS has become linked to optical networking
…the term ASON (Automatically Switched Optical Network) and is often used interchangeably with GMPLS…
GMPLS protocols are designed to handle a variety of networking technologies
Optical networks are just one such technology
MPLS data planes are another
MPLS is a data plane technology and control plane protocols
GMPLS can control an MPLS data network
The base protocols are the same
Routing protocols (IS-IS and OSPF)
Signaling protocol (RSVP-TE)
GMPLS is safe
Based on well-proven MPLS-TE
Good experiences in non-packet networks
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6. What Can GMPLS Do that MPLS-TE Can’t?
Separate control channel from data channel
MPLS-TE assumes that the control traffic flows in the same link as the data traffic
Implications for link identification in the control protocols
Implication for link failure scenarios
GMPLS disassociates the control and data channels
Supports many different technologies
Don’t need routing adjacency between ends of data links
Scaling benefits in the control plane
Need additional link identifiers
Need to handle control and data channel failures separately
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7. What Else Can GMPLS do? Bidirectional LSPs Link-level protection
Single signaling exchange establishes symmetrical LSP
Link-level protection
Advertise and use protection capabilities of links
Priority-based bandwidth
Leverage set-up priority with bandwidth pools
Packet-centric link parameters
Minimum LSP bandwidth
MTU
SRLGs
Integrated multi-layer networking
Becoming increasingly important in “packet optical networks”
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8. Differences in Routing Protocols
MPLS-TE uses a top-level information element for the TE information in the routing protocol
Extended IS reachability TLV in IS-IS
Opaque TE LSA in OSPF
MPLS-TE information is carried in sub-TLVs
GMPLS introduces new sub-TLVs for additional information
Link local identifiers (because TE link is not control channel)
Link protection capabilities
Priority-based bandwidth pools
Interface switching capabilities
Minimum LSP size and MTU
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9. What Happens if I Mix MPLS-TE and GMPLS Routing?
MPLS nodes will:
Generate only MPLS-TE information
Receive GMPLS information and re-flood it
Receive GMPLS information and not use it
See all nodes in the network as if MPLS-TE capable
GMPLS nodes will:
Generate only GMPLS information
Receive MPLS-TE information and re-flood it
Perceive MPLS-TE nodes as sending deficient information
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10. Differences in Signaling Protocols
Changes in most basic label processing
Label request (mandatory on Path)
MPLS-TE Label Request (C-Num = 19, C-Type = 1)
Generalized Label Request (C-Num = 19, C-Type = 4)
Label (mandatory on Resv)
MPLS-TE Label (C-Num = 16, C-Type = 1)
Generalized Label (C-Num = 16, C-Type = 2)
This is the fundamental distinguisher
Many new protocol objects in RSVP-TE
New objects are optional for inclusion but must be processed
Some new C-Types of existing objects
Only expected if Generalized Label Request is used
Many new protocol procedures
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11. What Happens if I Mix MPLS-TE and GMPLS Signaling?
MPLS nodes will:
Generate only MPLS-TE messages
Receive GMPLS messages and reject them
They carry unknown objects
Fail to set up LSPs with adjacent GMPLS nodes
GMPLS nodes will:
Generate only GMPLS messages
Receive MPLS-TE messages and reject them
They carry the wrong label-request/label objects
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12. Feature Creep The Risks of Protocol Extension
How do we pull GMPLS features into our MPLS-TE network?
Vendors are looking to add value
Providers demand features in RFQs
Vendors look for “quick fixes” in response
Result is MPLS-TE with some bolt-on features
Features are usually taken from GMPLS RFCs
Sometimes the wheel gets reinvented
Different vendors pick up different features
Interoperability may be compromised
Over time the mix of features becomes complicated
Networks become hard to build and operate
My conclusion
If we want the function of GMPLS we should use GMPLS
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13. How to Achieve Interoperability
Important to agree interoperability is required
Fundamental to the success of the Internet
Interoperability requires implementation of open standards
Protocol extensions will always be needed
Must be backward compatible
Where backward compatibility is broken we must migrate
Migration strategy must be agreed
It is an element of interoperability
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14. Strategies For Migration
Explored by CCAMP working group of the IETF
RFC 5145
Framework for MPLS-TE to GMPLS Migration
Interworking through gateways
Protocol translation
Controlled feature creep
“Agreed” introduction of protocol objects
Interworking through overlays
Network layers to separate protocol stacks
Integrated MPLS and GMPLS function
Dual-capability nodes within MPLS-TE networks
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15. MPLS-TE / GMPLS Gateways
Known as the Interworking Model or Island Model
Islands of MPLS-TE nodes and GMPLS nodes
Interaction through Gateway nodes
Responsible for “mapping” protocol elements
Routing gateway
Does not need to strip GMPLS info
Doing so would cause problems when flooding back into GMPLS network
Cannot create GMPLS info
GMPLS network will not see MPLS network “correctly”
Signaling
LSPs initiated in MPLS network can be mapped OK
LSPs initiated in GMPLS network might not be possible (e.g. bidirectional)
How to position gateways?
In the extreme, every other node is a gateway!
GMPLS
MPLS
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16. Controlled Feature Creep
Known as the Phased Model
Vendors introduce new GMPLS features into their MPLS-TE products
Operators deploy new function as they need it
This is the default way we are operating today
It is very risky!
Will vendors add features as backward compatible?
Are operators required to upgrade the whole network?
Will all vendors add the same features in the same way?
Will interoperability be compromised?
Will the feature genuinely be available if only some nodes support it?
An understandable approach in response to an RFQ
Reactive design is never the best
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17. Overlay Networks GMPLS is good at overlay networks
RFC 5212 GMPLS-based Multi-Layer Networks
RFC 5146 Support of MPLS-TE over GMPLS Networks
Augmented model has dual-capability border nodes
LSP across GMPLS network provide virtual links in the MPLS-TE network
GMPLS islands introduced in the MPLS-TE sea
MPLS-to-MPLS LSPs are supported
LSPs within the GMPLS island are supported
As migration progresses we have MPLS puddles in a GMPLS continent
Can’t do GMPLS over MPLS-TE overlay
Can’t do MPLS-to-GMPLS LSPs (requires translation)
MPLS
GMPLS
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18. Integrated MPLS-TE and GMPLS Networks
Network nodes are either
MPLS-TE only (legacy nodes)
Dual capable MPLS-TE and GMPLS nodes (new nodes)
Routing
Legacy advertises MPLS-TE
New advertises GMPLS
RFC 5073 : Advertise signaling capabilities
Path computation looks for consistent paths
Default is MPLS-TE
GMPLS is used if a path can be found
Signaling
Depends on path selected
Allows piecemeal migration
Add new dual capability nodes
Upgrade MPLS-TE nodes
When all nodes are GMPLS-capable, turn off MPLS-TE
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19. Why is Now a Good Time?
MPLS-TE deployments have proven the concept of traffic engineering in MPLS networks
There is a drive towards operating MPLS-TE as a transport environment
cf. MPLS-TP (T-MPLS)
Requires advanced functions
Control/data separation
Bidirectional services
Advanced protection and recovery
GMPLS was developed specifically for transport
Migration will take time
Start now!
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20. What Should Be Done and Who Should Do It?
Select a migration strategy
IETF recommends Integrated Networks model
This appears to be the safest and most flexible solution
Get vendors to implement
New shipments need to be dual capability nodes
MPLS-TE shipments are still OK, but don’t progress toward migration
Implementation is a relatively small step
Incremental on the MPLS-TE codebase
Leverage on vendors is the operator’s RFI
Ask for about GMPLS features with interoperability
Ask about vendor’s migration strategy
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21. Conclusion GMPLS offers advanced MPLS-TE functions
Highly desirable as MPLS-TE becomes more transport-oriented
Need smooth way to introduce GMPLS into deployed MPLS-TE networks
The industry must agree a migration model if interoperability is to be guaranteed
The Integrated Model provides the easiest migration
Vendors need to implement and ship
Vendors who implement first may gain an advantage
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22. Questions
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