Transcript Should I Migrate My MPLS-TE Network to GMPLS

Should I Migrate My MPLS-TE
Network to GMPLS?
And if so, how?
Adrian Farrel
Old Dog Consulting
[email protected]
www.mpls2008.com
Old Dog Consulting
Questions, Only Questions
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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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MPLS-TE
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Traffic engineering in MPLS packet networks
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Need to know what network resources are available
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Additions to IGP routing protocols (IS-IS and OSPF)
Distributes bandwidth availability with link state
Need to compute routes for LSPs
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Place traffic to optimize network use
Reserve resources to guarantee QoS
Establish LSPs for protection and restoration
NMS, ingress LSR, or PCE
Need to signal for LSP establishment
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RSVP-TE
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GMPLS
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Origins lie in control of WDM systems
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Now extended to cover a variety of technologies
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MPλS
Labels are re-invented and wavelengths
Resources are implicit
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)
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To distribute information about links and resources
To establish LSPs
To test and exchange information about data links
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How Different is GMPLS?
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GMPLS has become linked to optical networking
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GMPLS protocols are designed to handle a variety of
networking technologies
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…the term ASON (Automatically Switched Optical Network) and is
often used interchangeably with GMPLS… www.wikipedia.org
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
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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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What Can GMPLS Do that MPLS-TE Can’t?
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Separate control channel from data channel
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MPLS-TE assumes that the control traffic flows in the
same link as the data traffic
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Implications for link identification in the control protocols
Implication for link failure scenarios
GMPLS disassociates the control and data channels
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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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What Else Can GMPLS do?
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Bidirectional LSPs
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Link-level protection
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Leverage set-up priority with bandwidth pools
Packet-centric link parameters
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Advertise and use protection capabilities of links
Priority-based bandwidth
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Single signaling exchange establishes symmetrical LSP
Minimum LSP bandwidth
MTU
SRLGs
Integrated multi-layer networking
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Becoming increasingly important in “packet optical networks”
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Differences in Routing Protocols
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MPLS-TE uses a top-level information element for the TE
information in the routing protocol
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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
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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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What Happens if I Mix MPLS-TE and GMPLS
Routing?
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MPLS nodes will:
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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:
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Generate only GMPLS information
Receive MPLS-TE information and re-flood it
Perceive MPLS-TE nodes as sending deficient
information
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Differences in Signaling Protocols
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Changes in most basic label processing
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Many new protocol objects in RSVP-TE
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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
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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What Happens if I Mix MPLS-TE and GMPLS
Signaling?
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MPLS nodes will:
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Generate only MPLS-TE messages
Receive GMPLS messages and reject them
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They carry unknown objects
Fail to set up LSPs with adjacent GMPLS nodes
GMPLS nodes will:
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Generate only GMPLS messages
Receive MPLS-TE messages and reject them
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They carry the wrong label-request/label objects
Fail to set up LSPs with adjacent GMPLS nodes
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Feature Creep
The Risks of Protocol Extension
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How do we pull GMPLS features into our MPLS-TE network?
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Result is MPLS-TE with some bolt-on features
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Vendors are looking to add value
Providers demand features in RFQs
 Vendors look for “quick fixes” in response
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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How to Achieve Interoperability
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Important to agree interoperability is required
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Interoperability requires implementation of open
standards
Protocol extensions will always be needed
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Fundamental to the success of the Internet
Must be backward compatible
Where backward compatibility is broken we must
migrate
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Migration strategy must be agreed
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It is an element of interoperability
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Strategies For Migration
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Explored by CCAMP working group of the IETF
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RFC 5145
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Interworking through gateways
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“Agreed” introduction of protocol objects
Interworking through overlays
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Protocol translation
Controlled feature creep
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Framework for MPLS-TE to GMPLS Migration
Network layers to separate protocol stacks
Integrated MPLS and GMPLS function
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Dual-capability nodes within MPLS-TE networks
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MPLS-TE / GMPLS Gateways
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Known as the Interworking Model or Island Model
Islands of MPLS-TE nodes and GMPLS nodes
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Interaction through Gateway nodes
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Responsible for “mapping” protocol elements
GMPLS
MPLS
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Routing gateway
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Does not need to strip GMPLS info
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Cannot create GMPLS info
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GMPLS network will not see MPLS network “correctly”
Signaling
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Doing so would cause problems when flooding back into GMPLS network
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?
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In the extreme, every other node is a gateway!
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Controlled Feature Creep
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Known as the Phased Model
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This is the default way we are operating today
It is very risky!
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Vendors introduce new GMPLS features into their MPLS-TE
products
Operators deploy new function as they need it
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
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Reactive design is never the best
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Overlay Networks
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GMPLS is good at overlay networks
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RFC 5212 GMPLS-based Multi-Layer Networks
RFC 5146 Support of MPLS-TE over GMPLS Networks
MPLS
GMPLS
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Augmented model has dual-capability border nodes
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GMPLS islands introduced in the MPLS-TE sea
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LSP across GMPLS network provide virtual links in the MPLS-TE network
MPLS-to-MPLS LSPs are supported
LSPs within the GMPLS island are supported
As migration progresses we have MPLS puddles in a GMPLS continent
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Can’t do GMPLS over MPLS-TE overlay
Can’t do MPLS-to-GMPLS LSPs (requires translation)
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Integrated MPLS-TE and GMPLS Networks
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Network nodes are either
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Routing
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Default is MPLS-TE
GMPLS is used if a path can be found
Signaling
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Legacy advertises MPLS-TE
New advertises GMPLS
RFC 5073 : Advertise signaling capabilities
Path computation looks for consistent paths
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MPLS-TE only (legacy nodes)
Dual capable MPLS-TE and GMPLS nodes (new nodes)
Depends on path selected
Allows piecemeal migration
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Add new dual capability nodes
Upgrade MPLS-TE nodes
When all nodes are GMPLS-capable, turn off MPLS-TE
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Why is Now a Good Time?
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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
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cf. MPLS-TP (T-MPLS)
Requires advanced functions
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Control/data separation
Bidirectional services
Advanced protection and recovery
GMPLS was developed specifically for transport
Migration will take time
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Start now!
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What Should Be Done and Who Should Do It?
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Select a migration strategy
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Get vendors to implement
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IETF recommends Integrated Networks model
This appears to be the safest and most flexible solution
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
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Ask for about GMPLS features with interoperability
Ask about vendor’s migration strategy
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Conclusion
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GMPLS offers advanced MPLS-TE functions
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Need smooth way to introduce GMPLS into deployed
MPLS-TE networks
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Highly desirable as MPLS-TE becomes more transportoriented
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
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Vendors who implement first may gain an advantage
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Questions
[email protected]
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