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 adrian@olddog.co.uk www.mpls2008.com Old Dog Consulting

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? Old Dog Consulting

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 Old Dog Consulting

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 Old Dog Consulting

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… www.wikipedia.org 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 Old Dog Consulting

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 Old Dog Consulting

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” Old Dog Consulting

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 Old Dog Consulting

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 Old Dog Consulting

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 Old Dog Consulting

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 Old Dog Consulting

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 Old Dog Consulting

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 Old Dog Consulting

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 Old Dog Consulting

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 Old Dog Consulting

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 Old Dog Consulting

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 Old Dog Consulting

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 Old Dog Consulting

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! Old Dog Consulting

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 Old Dog Consulting

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 Old Dog Consulting

Questions adrian@olddog.co.uk Old Dog Consulting