GMPLS Overview Generalized MPLS

Transcription

1 GMPLS Overview Generalized MPLS Hanyang Univ ( jijung@hanyang.ac.kr )

2 Outline GMPLS Overview Draft-ietf-ccamp-gmpls-architecture-00.txt GMPLS IGP Extension Draft-ietf-ccamp-ospf-gmpls-extensions-00.txt Draft-ietf-ccamp-isis-gmpls-extensions-04.txt GMPLS Signaling Extension Draft-ietf-mpls-generalized-signaling-06.txt Draft-ietf-mpls-generalized-rsvp-te-05.txt Draft-ietf-mpls-generalized-cr-ldp-04.txt GMPLS LMP Draft-ietf-mpls-lmp-02.txt Draft-ieft-mpls-lsp-hierarchy-02.txt Draft-ietf-mpls-bundle-00.txt

3 GMPLS Architecture Abstract MPLS time-division (e.g. SDH/SONET, PDH, G.709) Wavelength (lambdas) Spatial Switch (e.g. Incoming port or fiber to outgoing port of fiber GMPLS

4 Abstract Traditional MPLS supports packet switching Future data and transmission Networks Elements Router Switch DWDM systems ADM PXC(OXC) Dynamically Provision Resources Network Survivability using protection and restoration techniques GMPLS

5 GMPLS Goals A single network-wide control plane to Distribute optical transport network topology state Set up optical channel trails Support traffic engineering functions and enable protection and restoration capabilities Simplify the integration of optical switches, optical transport, and label switching routers Enhances service provider revenues New services creation, Faster provisioning, Operational efficiency

6 Multiple Switching Types Packet-Switch Capable(PSC) interfaces Routers(IP herder, MPLS shim header) Time-Division Multiplex Capable(TDM) interfaces SDH/SONET Cross-Connect, ADM Lambda Switch Capable(LSC) interfaces Wavelength Fiber-Switch Capable(FSC) interfaces Photonic Cross-Connect

7 Extends MPLS to support multiple switching types TDM(SONET/SDH) Switching Lambda Switching Waveband switching Port Switching

8 Multiple Switching Types

9 Multiple Switching Types A Circuit can be established only between, or through, interfaces of the same type. e.g SDH circuit, Optical trail, Light path etc. In GMPLS all these circuit -> Label Switched Path A hierarchy of LSPs Nested LSP(LSP within LSP) Already available in traditional MPLS On Same interface or between different interfaces Same interface e.g a lower order SDH/SONET LSP(VC-12) nested in a higher order SDH/SONET LSP(VC-4) Different interface FSC > LSC> TDM > PSC

10 Extension of MPLS Control Plane GMPLS Extend control planes to support of the four classes of interfaces GMPLS Building Block The Main Building Blocks To build a consistent control plane for multiple switching layers. Different models can be applied : e.g.overlay, peer, augmented/integrated, A number of combinations are possible.

11 Extension of MPLS Control Plane Overlay model Two independent control planes IP/MPLS routing Optical domain routing Router is client of optical domain Optical topology invisible to routers Routing protocol stress scaling issues Similar to IP over ATM Peer Model Single integrated control plane Router and optical switches are peers Optical topology is visible to routers Similar to IP/MPLS model?

12 Extension of MPLS Control Plane GMPLS can be summarized as follows The Concepts of Generalized Interface A new Link Management Protocol(LMP) To address issues related to link management in optical networks using photonic switches Traffic Engineering Enhancements Enhancements to OSPF/IS-IS To advertise availability of optical resources in the networks(e.q. Generalized representation of various link types, bandwidth on wavelengths, link protection type, fiber identifiers) Enhancements to RSVP-TE/CR-LDP To allow a LSP to be explicitly specified across the optical core. Scalability enhancements such as hierarchical LSP formation, Link Bundling

13 Key Difference(1) MPLS-TE an intermix links (e.g. links between routers, or ATM-LSRs, or between ATM-LSRs and routers) GMPLS including left box, timeslot, or wavelength or fiber Start and end on a IP router bandwidth allocation in continuous spectrum uni-directional Start and end on similar type of LSRs bandwidth allocation in discrete units support for bi-directional

14 Key Difference(2) GMPLS Expected to have(much) fewer labels on non-psc links than on PSC links Forwarding Adjacency(FA) mechanism to improve bandwidth utilization to aggregate forwarding state allowing the number of required labels to be reduced Allowing for a label to be suggested by an upstream node to reduce setup latency GMPLS with RSVP-TE supports an RSVP specific mechanism for rapid failure notification

15 Key Difference(3) An ingress or other upstream node may restrict the labels(label Set) that may be used by an LSP along either a single hop or along the whole LSP path Constraining Label Choice Some switches cannot modify labels (lambdas) May want to restrict available resources Advertise available lambdas using Label Set Label set is allowed to have just one member

16 GMPLS Scalability Enhancement GMPLS The overall number of links in optical/tdm can be several orders of magnitude larger than that of an MPLS network -> Link Bundling Identifying which port on a network element is connected to which port on a neighboring network element is also a major management burden and highly error-prone -> LMP Fast fault detection and isolation, and fast failover to an alternate channel are needed -> LMP The user data carried in the optical domain is transparently switched to increase the efficiency of the network -> LMP

17 GMPLS Scalability Enhancement LSP Hierarchy

18 GMPLS Scalability Enhancement LSP Hierarchy Aggregate multiple LSPs inside a bigger LSP Intermediate nodes see the external LSP only No need to maintain forwarding states for each internal LSP FA(Forwarding Adjacency) An LSR uses MPLS-TE procedures to create and maintain an LSP The LSR may announce this LSP as a Traffic Engineering Link into IS-IS/OSPF. Such a link a forwarding adjacency We refer to the LSP as the FA-LSP the bandwidth of FA-LSP must be at least as big as the LSP, but may be bigger if only discrete bandwidths are available for the FA-LSP

19 GMPLS Scalability Enhancement Link Bundling When a pair of LSRs is connected by multiple links, it is possible to advertise several(or all) of these links as a single link into OSPF and/or IS-IS. To improve routing scalability by reducing the amount of information that has to be handled by OSPF and/or IS-IS All component links in a bundle must begin and end on the same pair of LSRs, share common characteristics.

20 GMPLS Routing & Addressing model(1) GMPLS is based on the IP routing and addressing model IPv4 / IPv6 addresses are used to identify interfaces traditional (distributed) IP routing are also reused IP addresses are used identify interfaces of IP hosts and routers more generally to identify and PSC and non-psc interfaces IP routing protocols are used find routes for IP datagrams find routes for non-psc circuits by using a CSPF algorithm

21 GMPLS Routing & Addressing model(2) Re-using existing IP routing protocols allows for non-psc layers to take advantages of years for IP routing Extensions for inter-domain(bgp) traffic engineering -> further study Extensions for intra-domain traffic engineering used of linkstate routing protocol -> OSPF-TE, IS-IS IS-TE Optional mechanisms can be used to increase the scalability of the addressing and the routing -> Link bundling

22 GMPLS TE Links 1. Links that are non-psc may yet have TE properties OSPF adjacency cannot be brought up directly on such links 2. An LSP can be advertised as a point-to-point TE link in the routing protocol as a Forwarding Adjacency(FA) Advertised TE link need no longer be between two OSPF neighbors 3. A number of links may be advertised as a single TE link for improved scalability Link Bundling There is no longer a one-to-one association of a regular adjacency and a TE link

23 RSVP-TE / CR-LDP Extensions PATH/REQUEST SONET/SDH ADM RESV/MAPPING SONET/SDH ADM PATH / REQUEST Message Generalized Label Request, Explicit Route Upstream Label, Label Set, Suggested Label RESV / MAPPING Message Generalized Label

24 RSVP-TE / CR-LDP Extensions Generalized Label Request LSP Encoding Type: 8 bits Indicates the type of technology LSP Payload Type (G-PID): 16 bits An identifier of the client layer of LSP Bandwidth Encoding Generalized Label Extends to include support of time-slot, wavelength, space division multiplexed position Only carries a single level of label Variable length label parameter

25 RSVP-TE / CR-LDP Extensions Waveband Switching Special case of lambda switching Set of contiguous wavelengths which can be switched together Allow tighter separation of the individual wavelength Suggested Label Permits the upstream node to start configuring it s hardware with the proposed label before the label is communicated by the downstream node Can reduce setup latency

26 RSVP-TE / CR-LDP Extensions Label Set Used to limit the label choices of a downstream node to a set of acceptable labels Bi-directional LSP setup Indicated by the presence of an Upstream Label object/tlv in PATH/REQUEST message

27 RSVP-TE / CR-LDP Extensions Notification (RSVP-TE only) Signaling extensions that modify error handling, enable expedited notification of failures and other events Explicit Label Control Can provide very detailed Explicit Routes, including the Label Protection Flags Indicate link related protection attributes of a requested LSP

28 Link Bundling Bundled link 1 Bundled link 2 A pair of Label Switching Routers (LSRs) may be c connected by several (parallel) links. From the MPLS Traffic Engineering point of view for r reasons of scalability it may be desirable to advertise a all these links as a single link into OSPF and/or IS-IS. = =>(link bundling) Bundled link =A kind of Traffic Engineering link

29 Link Bundling Reducing the amount of information is accomplished by performing Information aggregation/abstraction Restrictions on bundling: All component links in a bundle must: Begin and end on the same pair of LSRs Have the same Link Type ( Point-to-point or multi-access) Have the same Traffic Engineering metric Have the same Link Multiplex Capability

30 Link Management Protocol Running between neighboring nodes Four basic functions of LMP Control channel management Link connectivity verification Link property correlation Fault isolation Authentication

31 Link Management Protocol Control channel: Bundled link has bi-directional control channels and component links Control channels consist of a primary control channel and back-up control channel(in the event of a primary control channel failure) Control channel can exchange: MPLS control-plane information (Such as link provisioning and fault isolation by using LMP) Path management and label distribution information (By using signaling protocol such as RSVP-TE or CR-LDP ) Topology and state distribution information (By using traffic engineering extended protocols such as OSPF and IS-IS)

32 Link Management Protocol Control channel management: To establish and maintain link connectivity between neighboring nodes Being done using Hello messages Verifying link connectivity: The primary control channel: Being first verified, and connectivity maintained, using the Hello protocol Component link connectivity: Being verified by exchanging Ping-type Test messages over each of the component links specified in the bundled link

33 Link Management Protocol Link property correlation: A Link Summary message is transmitted in order to add component links to a bundled link, change Link Ids, or change a link's protection mechanism The Link Summary message can be exchanged at any time a link is UP Fault localization: Fault detection If one or more component links fail between two nodes, a mechanism must be used to rapidly locate the failure so that appropriate protection/restoration mechanisms can be initiated