1 Generalized Multiprotocol Label Switching Konstantinos Lizos PhD Student – Spring 2015 University of Oslo (UiO) The Faculty of Mathematics and Natural Sciences Department of Informatics Course INF Materials mainly extracted by [1] A. Banerjee, J. Drake, J. Lang and B. Turner, “GMPLS: An Overview of Signaling Enhancements and Recovery Techniques”

2 Principles of MPLS Constraint-based routing as opposed to best effort internet service MPLS addition : connectivity abstraction (end-to-end) Explicitly routed point-to-point path as opposed to multipoint to point (unicast) path in conventional IP networks

MPLS Limitations MPLS’s inability to establish bidirectional connections in a single request and the absence of mechanisms to account for protection bandwidth in lower-priority traffic. A link or node failure along the routes of established service connections can only be handled locally or along the nodes of the path 3

Evolution of GMPLS 4 MPLambaS Proposal GMPLS Extensions to IP signaling RSVP-TE & CRLDP Extensions to IP Routing OSPF-TE & ISIS-TE IETF TE Working Group IETF MPLS Working Group Requirements for TE over MPLS

Origins Traces back to multi-protocol lambda switching (MPλS) originally proposed by Awduche and Rekhter (1999) GMPLS has generalized the MPλS concept, so that the same control plane concepts can be used in other switched transport technologies, such as TDM, optical as well as cell switched networks. 5

GMPLS extends the concept of label 1)in a packet-switched network, a label represents a short tag attached to a packet. 2)in a TDM network, a label represents a time slot 3)in a wavelength-switched network, a label represents a wavelength 4)In a fiber-switched network, a label represents a fiber. 6

GMPLS Interface Expansion 7 PSC Expand MPLS functionality to sustain extra interfaces in addition to packet switch Fiber-Switch Capable (FSC) Packet Switch Capable (PSC) Router/ATM Switch/Frame Reply Switch Time Division Multiplexing Capable (TDMC) SONET/SDH ADM/Digital Crossconnects Lambda Switch Capable (LSC)) All Optιcal ADM or Optical Crossconnects (OXC) LSPs of diverse interfaces can be nested inside another LSC TDMC LSC FSC Copyright ® Lizos

Techniques by GMPLS devices Protection and restoration techniques used by GMPLS devices –Fault isolation –Fault localization –Fault notification –Fault mitigation 8

Signaling GMPLS requires that an LSP starts and ends on similar types of devices. MPLS is designed so that the control plane is logically separate from data plane GMPLS extends this concept, by allowing the control plane to be physically diverse from the associated data plane. 9

Hierarchical LSPs GMPLS supports the concept of hierarchical LSPs, which occurs when an LSP is tunneled inside an existing higher-order LSP so that the preexisting LSP serves as a link along the path of the new LSP. 10

R 10 Nested LSP 11 Fiber LSP 4 λ LSP 3 Time slot (TDM) LSP 2 Packet LSP 1 LSP 4 LSP 3 LSP 2 LSP m from a Gigabit Enet 500 m from a Gigabit Enet OC-12c OC-12c OC-192 OC-192 Fiber Fiber Router acting Router acting as an IP LSR as an IP LSR SONET switch/mix SONET switch/mix Optical OEO switch Optical OEO switch Photonic switch Photonic switch O R S PP4 P5 P6 O3 O7 S2S8 R1R1 R9R9 R0R0

Process of creating an LSP Assumption: RSVP-TE signaling extension (defined in GMPLS) assumes required bandwidth is available on each of the links Residual bandwidth available in LSP hierarchy is advertised by the Interior Gateway Routing Protocols (IGP) –R1 announces packet-switch capable link (PSC) –S2 announces time division multiplex (TDM) link –O3 announces lambda-switch capable (LSC) links 12

Creating an LSP 13 Timeline R0R0 R1R1 S2S2 O3O3 P4P4 P5P5 P6P6 O7O7 S8S8 R9R9 R 10 Path 1 Path 2 Path 3 Path 4 Resv 4 LSP 4 completes Resv 3 LSP 3 completes LSP 2 completes LSP 1 completes Resv 2 Resv 1

Bidirectional LSP Setup Bidirectional optical LSPs (or lightpaths) is supported by GMPLS Supposedly, both directions of such LSPs have the same TE requirements Initiator: starting establishing an LSP Terminator: LSP destination node Bidirectional LSP: only one initiator and one terminator MPLS defines unidirectional LSP. To attain bidirectional LSP setup, two independent LSPs must be formed in opposite directions. Disadvantages: I) high latency, II) increased control overhead, III) P(A,B)=P(A)P(B)  min{P(A),P(B)} 14

Notify messages Central requirement: response to network failures must be quick and decisions must be made intelligently A node passing transit connections can notify node(s) responsible for restoring connections when failures occur. Notify message has been added to RSVP-TE for GMPLS to convey to non-adjacent nodes of LSP-related failures. Applications for Notify message Inform about a degraded link (control plane failed, data plane still functional*) * Control plane failures may limit management features but doesn’t always justify termination of an LSP. 15

GMPLS Protection and Restoration Techniques Key feature for constructing a common control plane involves coordination among signaling, routing and link management protocols to enable intelligent fault management consisting of I)Detection, II) Localization III) Notification and IV) Mitigation 16

Achieving the goal for protection and restoration Protection and restoration can traditionally been addressed by using two techniques:  Path switching: failure is addressed at the path endpoints (i.e. the path initiating and terminating nodes)  Path protection: secondary protection paths are preallocated  Path restoration: connections are rerouted, either dynamically (could have precalculated paths)  Line Switching: failure is addressed at the transit node where the failure is detected  Span protection: traffic is switched to an alternate parallel channel or link connecting the same two nodes  Line restoration: traffic is switched to an alternative route between the two nodes 17

Protection mechanisms In summary, protection mechanisms are  1+1 protection: payload is transmitted simultaneously over two disjoint paths (selector chooses best signal)  M:N protection: M predesignated backup paths are shared between N primary paths  1:N protection: 1 preallocated backup path is shared among N primary paths  1:1 protection: 1 dedicated backup path is preallocated for 1 primary path 18

Restoration mechanisms Typically takes more time to react & resolve failures by switching to alter- nate paths, due to dynamic nature. Restoration can be implemented both at the source or an intermediate node, once the responsible node has been notified. Failure notification is performed using notify procedures or standard error messages 19

Conclusions GMPLS provides the necessary linka- ge between the IP and photonic layers, allowing interoperable, scalab- le, parallel and cohesive evolution of networks in the IP and photonic dimensions. Basically, GMPLS resolves the main problem of scalability by segregating the transport network from the data. 20

Conclusions / Q & A New traffic flows and proliferation of mobile terminals require robust high- capacity structures that support fast provisioning, other than voice. GMPLS-based products can be applied in existing networks to decrease costs without impacting service quality. Flexible M:N protection and restoration capabilities of GMPLS allow efficient addressing of network survivability. 21

References A. Banerjee, J. Drake, J. Lang and B. Turner, “GMPLS: An Overview of Signaling Enhancements and Recovery Techniques”, IEEE Communications Magazine, Vol:39, Issue:7, p.p: , doi: / Daniel O. Awduche, Bijan Jabbari, "Internet traffic engineering using multi- protocol label switching (MPLS)", Computer Networks 40 (2002)

23 Types of switches Multiplexing technique on data-plane links Admission control in control plane? Circuit switch (CS) - position based (port, time, lambda) Packet switch (PS) - header based Connectionless (CL) - no admission control Not an option e.g., Ethernet Connection-oriented (CO) - admission control e.g., telephone SONET WDM Virtual-circuit e.g., MPLS, ATM

24 Types of networks Support function Network type Addressing (in data or control plane?) RoutingSignaling Connectionless (CL)Data plane  Circuit Switched (CS) Control plane Virtual circuit (VC) Control plane Connection-oriented