Network Working Group D. Wang Internet-Draft Z. Wang Intended status: Informational Q. Xiang Expires: May 1, 2009 F. Gao ZTE Corporation October 28, 2008 PCECP Requirements and Extensions of Alternate Routing for Wavelength Switched Optical Networks draft-wang-pce-wson-alternate-routing-00.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on May 1, 2009. Abstract This memo provides application-specific requirements and extensions of alternate routing for the support of Wavelength Switched Optical Networks (WSON). Wang, et al. Expires May 1, 2009 [Page 1] Internet-Draft PCECP Extensions of AR for WSON October 2008 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions used in this document . . . . . . . . . . . . . . 3 3. Background . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 5. PCECP Extended Requirements for AR . . . . . . . . . . . . . . 5 5.1. AR Computation Policy . . . . . . . . . . . . . . . . . . 5 5.2. Extended PCE Request Information for AR . . . . . . . . . 6 5.2.1. Loose Constraints Inquiry . . . . . . . . . . . . . . 7 5.2.2. Constraint Routing Inquiry Strategy . . . . . . . . . 7 5.2.3. Sequence Strategy of Alternate Routes . . . . . . . . 8 5.2.4. Maximum Complexity of Time and Space about AR Computation . . . . . . . . . . . . . . . . . . . . . 9 5.3. Response of Alternate Routes From PCEs . . . . . . . . . . 9 5.3.1. Basic Information of Alternate Routes . . . . . . . . 9 5.3.2. Form of Alternate Routes . . . . . . . . . . . . . . . 10 5.3.3. Content of Each hop in Alternate Routes . . . . . . . 10 5.4. AR Computation Strategy with Inclusion Constraints . . . . 11 5.5. The Relationship between Primary Route and Backup Route in AR . . . . . . . . . . . . . . . . . . . . . . . 11 5.6. Re-routing of Optimization under AR . . . . . . . . . . . 12 5.7. Re-routing of Fault Recovery under AR . . . . . . . . . . 12 5.8. Hierachical Routing in AR Computation . . . . . . . . . . 12 6. PCECP Extended Requirements for AR . . . . . . . . . . . . . . 13 6.1. Subobject of AR Extended Constraints . . . . . . . . . . . 13 6.2. Requset of Alternate Routes . . . . . . . . . . . . . . . 16 6.3. Response of Alternate Routes . . . . . . . . . . . . . . . 17 6.3.1. Basic Information Object . . . . . . . . . . . . . . . 17 6.3.2. Alternate Routes Subobjects . . . . . . . . . . . . . 18 7. Manageability Considerations . . . . . . . . . . . . . . . . . 20 7.1. Control of Function and Policy . . . . . . . . . . . . . . 20 7.2. Information and Data Models . . . . . . . . . . . . . . . 21 7.3. Liveness Detection and Monitoring . . . . . . . . . . . . 21 7.4. Verifying Correct Operation . . . . . . . . . . . . . . . 21 7.5. Requirements on Other Protocols and Functional Components . . . . . . . . . . . . . . . . . . . . . . . . 21 7.6. Impact on Network Operation . . . . . . . . . . . . . . . 21 8. Security Considerations . . . . . . . . . . . . . . . . . . . 21 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 22 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 22 11.1. Normative References . . . . . . . . . . . . . . . . . . . 22 11.2. Informative References . . . . . . . . . . . . . . . . . . 23 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 23 Intellectual Property and Copyright Statements . . . . . . . . . . 25 Wang, et al. Expires May 1, 2009 [Page 2] Internet-Draft PCECP Extensions of AR for WSON October 2008 1. Introduction [RFC4655] respectively defines PCE Architectures and describes the routing generating mechanism when a PCC originates a LSP's routing request. In Wavelength Switched Optical Networks (WSON), PCE is a key way to provide routes for services. At the same time, some PCEs can also have a function of realizing Wavelength Assignment(WA). As a common sense, Routing and Wavelength Assignment (RWA) is the first problem that WSON has to face. Meanwhile, RWA is truly a Nondeterministic Polynominal-Complete(NP-C) problem. Whatever RWA computation architectures (such as Combined RWA, Separate Routing and WA, Routing with Distributed WA, etc) are all confronted with two inevitable and divided procedures: route calculation, wavelength assignment. In many cases, LSP signalling can not be normally runned by the Label Switching Routers(LSRs) in the given route that some PCE supplies,especially in typical WSON. It is mainly resulted from WA failing in the LSRs that the service connection passes. WA blocking becomes the direct reason. (About why WA blocking occurs, please refer to other related drafts.) So Alternate Routing(AR) is proposed for the problem of WA failings in WSON. Alternate paths have appeared in RFC4655. AR means the routing of a service request over a substitute route when a primary route is unavailable for immediate use. When head-end node fails to establish the service according to the first provided route by some PCE, it can choose other routes and go on analysis of WA along the selected route. The PCE Communication Protocol (PCECP) is the communication protocol used between a PCC and a PCE, and may also be used between cooperating PCEs. [RFC4657] sets out the common protocol requirements for PCECP. Additional application-specific requirements for PCECP are deferred to separate documents. This document provides a set of application-specific PCECP requirements and protocol enhancements for support of AR in WSON. 2. Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC-2119. 3. Background The WSON framework [WSON-FRAME] document defines the following RWA computation architectures. Wang, et al. Expires May 1, 2009 [Page 3] Internet-Draft PCECP Extensions of AR for WSON October 2008 o Combined RWA (CRWA) --- Both R and WA are performed at a single computational entity. This choice assumes that computational entity has sufficient WSON network link/node and topology information to be able to compute RWA. o Separate Routing and WA (SRWA) --- Separate entities perform R and WA. The path(s) obtained from the routing computational entity must be furnished to the entity performing WA. o Routing with Distributed WA (RDWA) --- R is performed at a computational entity while WA is performed in a distributed fashion across the nodes along the path. For the CRWA architecture, there are two possible computing entities: (i) the NE is the computational entity -- in this case, there is no separate PCE as the NE assumes PCE function; (ii) a separate PCE is the computational entity. For the SRWA architecture, there can be two variations: o A separate PCE will perform only WA while the NE performs the route calculation based on its local knowledge. In this case, the NE should furnish the route list to the PCE so that the PCE would be able to assign wavelength to the route. o One PCE performs the R function while another PCE performs the WA function in a tandem fashion. The fact that two PCEs are involved (one for R and the other for WA) could be invisible to the original PCC. For the RDWA architecture, the PCE is only responsible for R(i.e., path computation), not for exact WA. The exact assignment of wavelengths would be performed at the NEs along the path in a distributed fashion. However, the PCE may limit the wavelengths that can be used (i.e., by specifying a wavelength set to the NEs). 4. Terminology AR: Alternate Routing. AS: Autonomous System. CP: Control Plane. CRWA: Combined RWA. Wang, et al. Expires May 1, 2009 [Page 4] Internet-Draft PCECP Extensions of AR for WSON October 2008 CSPF: Constraint-based Shortest Path First. NE: Network Element. NMS: Network Mangagement System. ODU: Optical Channel Data Unit. ODUk: Optical Channel Data Unit-k. OSC: Optical Supervisory Channel. PCC: Path Computation Client. PCE: Path Computation Element. PCECP: PCE Communication Protocol. R: Routing. RDWA: R with Distributed WA. ROADM: Reconfigurable Optical Add/Drop Multiplexer. RWA: Route and Wavelength Assignment. SRWA: Separate RWA. TE: Traffic Engineering. WA: Wavelength Assignment. WDM: Wavelength Division Multiplexing. WSON: Wavelenght Switch Optical Network. 5. PCECP Extended Requirements for AR 5.1. AR Computation Policy The AR computation policy represents a set of rules which defines the relation between PCEs and the PCCs in term of route exchanges and protocol interaction. To summarize, the AR computation policy can be defined as the following two types: Wang, et al. Expires May 1, 2009 [Page 5] Internet-Draft PCECP Extensions of AR for WSON October 2008 o All the routes of one topology will be computated by PCEs in advance. In this case, routes computation will not depend on PCCs' requests. Periodically PCEs complete all routes computation of the topology which they know and save them in local caches. At the same time, once the known topology is changed(such as opaque lsas are aged, updated, added, etc.), routes computation also occur in the PCEs. And especially in CRWA's scenario, WA also can be previously solved in each route before PCCs' requests. In this way, when a PCC's request comes, the PCE can search the suitable route matched with the request's constraints among the saved routes. So it is good for the PCC that it does not takes the PCC time to wait for computating the route. But the method of preprocessing routing has defects, too. If all of saving routes does not meet the PCC's constraints, RWA process will fail. So it is fitter for the route inquiry with loose constraints. By the way, in "multiple PCE path computation" case(see [RFC4655] ), at least one of the PCEs must have the function of assembling partitional routes into a complete route ahead of time. o A real-time route computation will be executed by PCEs according to one PCC's request. In this case, route computation will not occur until the PCE receives a request from some PCC. Then the PCE will begin to compute the route according to the PCC's request including some constraints and the PCC has to wait for the PCE's computation. So the time of route computation will be added to the PCE's reponse delay time. In addition, the complexity of algorithm that the PCE uses will be considered. 5.2. Extended PCE Request Information for AR In [RFC4655] 5.1.16., [draft-ietf-pce-pcep-xro-06], and [draft-ietf- pce-pcep-16], constraints and request information have also been raised. On the basis of the list of generic information, extended information SHOULD be added in need of the AR case. The set of supported extended information SHOULD include at least the following: o The route direction. Used to indicate whether the alternate routes should satisfy the specified constraints in both forward and reverse directions. It includes two options: Wang, et al. Expires May 1, 2009 [Page 6] Internet-Draft PCECP Extensions of AR for WSON October 2008 - Unidirection. - Bidirection. o Upper limit of K. Used to limit the maximum number of alternate routes computed by the PCE. o Constraint routing inquiry strategy. o Sequence Strategy of Alternate Routes. o Maximum complexity of time and space about AR computation. 5.2.1. Loose Constraints Inquiry Commonly constraints are thinked as strict constraints. It means that AR computation MUST satisfy the constraints, else the PCE will repond AR computation failure. Here, loose constraint is introduced. If computed alternate routes just need meet at least one of the loose constraints, the PCE will respond them to the PCC successfully. Otherwise if no loose constraint can be met, the PCE will return a failing response. The loose constraints also contain Link, Node, Shared Risk Link Group (SRLG) inclusion/exclusion. Furthermore, these constraints can be combined and be arranged in priority. For the loose, the higher priority of the constraint is, the earlier the constraint will be met. The loose constraints are listed in descending order of priority: o Nodes includsion. o Links includsion. o SRLGs includsion. o Nodes excludsion. o Links excludsion. o SRLGs excludsion. o And the PCC can also combined the above constraints. 5.2.2. Constraint Routing Inquiry Strategy In [RFC4657] and [RFC3209], both strict routes and loose routes are mentioned. Just as RFC4657 has mentioned, routes constraints usually include Link, Node, Shared Risk Link Group (SRLG) inclusion/ Wang, et al. Expires May 1, 2009 [Page 7] Internet-Draft PCECP Extensions of AR for WSON October 2008 exclusion, etc. Now as a consrtaint inquiry prefercence, here we introduce the conception of constraint routing inquiry strategy and give the constructive definition of it. It includes four types: - Strict constraints inquiry only. AR computation MUST satisfy the constraints including all of the above-mentioned constraints. - Loose constraints inquiry only. At this moment, AR computation just need meet at least one of the above-mentioned constraints. If no constraint can be met, the PCE will return a failing response to the PCC. - Coexistence of them. Sometimes, Both Strict inquiry and loose inquiry are requested at the same time. Then PCEs should process them respectivly according to the former different ways. - Neither of them. Routing inquiry is performed without any constraints. 5.2.3. Sequence Strategy of Alternate Routes When the PCC asks alternate routes for PCEs, it is preferable to offer the alternate routes in a designated sequence. In that case, the PCC need to supply a sequence strategy in its request. In [RFC4657], the objective functions of unsynchronized and synchronized path computations are introduced to us. Based on them, till now, there are some sequence strategies summarized in WSON as following: - 00 Minimum aggregate te-metrics. It is the familiarest sequence type that is equal to CSPF strategy. - 01 Minimum hops number. In fact, this type is deduced from the above. We can look it as that the te-meteric of every hop that every path includes is one. Then if the hypothesis is formed, that will be the above type. - 02 Maximum disjoint nodes as possible. Sometimes, for the PCC's need, the alternate routes are sequenced under the consideration of nodes that routes inlcude being parted each other as possible. Supposing that when the PCC receives the PCE's successful response (Here, we consider the RDWA scenario .), it will use the first provided route to perform WA. Once WA fails in the used path, then another alternate route will be selected. It is more likely that WA succeeds using the path consisting of ultimately different nodes. So important this strategy is, and the next two strategies are homothetic. Wang, et al. Expires May 1, 2009 [Page 8] Internet-Draft PCECP Extensions of AR for WSON October 2008 - 03 Maximum disjoint links as possible. - 04 Maximum disjoint SRLGs as possible. - 05 Highest efficient use based on bandwidth granularity. In WSON, RWA processes of the sevices which in batch processing are initiated by the NMS will be computed at a variety of bandwidth granularities. Generally speaking, there are k kinds of bandwidth granularities according to ODUk supported by the transport plane. At this time, alternate routes computed by the PCE will be sequenced in the residual bandwidth of the links that the every alternate route contains and the bandwidth granularity that the sevice to be set up needs. For example, now there are three alternate routes for a service connection of which bandwidth granularity is ODU0. And the residual bandwidth granularities in their contained links are ODU1 ODU2, and ODU0 respectively. In this strategy, we can arrange such routes in the granularity order: ODU0, ODU1, ODU2. So in this method, we can avoid the fragment of free bandwidth appearing as possible. - 06 Highest load balancing degree. Load balancing problem has been cared for in AR. To some extent, it is similar to "maximize the residual bandwidth on the most loaded link" in RFC4657. Here, it is also used for the loaded SRLG. 5.2.4. Maximum Complexity of Time and Space about AR Computation In RFC4655 "6.4. PCE Discovery and load balancing, The PCC may learn PCE capabilities through static configuration, or it may discover the information dynamically." Besides the PCE capabilities described in RFC4655, by maximum complexity of time and space about AR computation, the PCC can estimate the PCE's capabilities. Once the time or the space for the PCC's AR computation exceeds this constraint, the PCE will respond AR computation failure and the PCC will select another appropriate PCE for its purposes under the control of policy. 5.3. Response of Alternate Routes From PCEs In the case of AR in WSON, the PCE should return the K alternate routes to the PCC. 5.3.1. Basic Information of Alternate Routes Basic information of alternate routes should include: Wang, et al. Expires May 1, 2009 [Page 9] Internet-Draft PCECP Extensions of AR for WSON October 2008 - the actual number of alternate routes that the PCE computes. - the algorithm's complexity of time and space. By this information, the PCC can learn the capability and efficiency of PCE, so that it can adjust the strategy and choose the suitable PCE in time. - the range of which the PCE is responsible for AR computation. It should include the areas' IDs, the sub areas' IDs that the PCE deals with. 5.3.2. Form of Alternate Routes The K alternate routes can be described in a serial format. Different routes can be distinguished by the head-end node's hop. And when the PCC receives the packets, it can extract every route by judging the head-end hops which contain the head and the end nodes' IDs. +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | basic information of alternate routes | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | the 1st route | head hop | hop1 | hop2' |.....| end hop | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | the 2nd route | head hop' | hop1' | hop2' |.....| end hop' | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | the kth route | head hop''| hop1''| hop2''|.....| end hop'' | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 5.3.3. Content of Each hop in Alternate Routes In RFC4657 "5.1.5.Path Computation Responses", the information which is responded by the PCE has been cared for. But it does not be described in detail and does not be extended. Especially in WSON, each hop of each alternate route should contain R and WA information. It MUST providing the following mandatory R information: - Node ID. - IP address of each hop's output interface. Wang, et al. Expires May 1, 2009 [Page 10] Internet-Draft PCECP Extensions of AR for WSON October 2008 - Metric of each hop. - Residual bandwidth of each hop. It MAY providing the following optional WA information : - Free wavelength set of each hop. It can be used for RDWA when WA process has not been executed. - Definite used wavelength of each hop by WA analysis. It can be used for CRWA when the PCE has the funciton of WA at the same time. 5.4. AR Computation Strategy with Inclusion Constraints It is well-known that inclusion constrains, such as nodes, links, SRLGs, and the combined separate the route from head to end nodes into several segments. In this case, AR computation will be performed in segment by at least one PCE . If the numbers of alternate sub-routes of segments are k1, k2, k3,....kn respectivly. Thus the number of full routes by assembling is at most k1*k2*k3....*kn considering perhaps there are repeated nodes, links and SRLGs among the sub-routes. The function of assembling sub- routes can be executed by a designated PCE. At last, the PCE will respond the full alternate routes to the PCC or go on to perform the WA analysis by them. and pay attention to isolate nodes appear. 5.5. The Relationship between Primary Route and Backup Route in AR For the purpose of Automatic Protection Switching (APS), the PCE can provide two kinds of routes, one is the primary route for the work connection and the other is the backup route for the protect connection. Between the primary and the backup routes, there are also some routing strategies as following: - completely disjoint links; - completely disjoint nodes; - completely disjoint SRLGs; - completely disjoint paths; In WSON, the RWA procedure of work and protection connections can be separated into two steps. The RWA of work connection with primary route is the first step, and the RWA of protection connection with Wang, et al. Expires May 1, 2009 [Page 11] Internet-Draft PCECP Extensions of AR for WSON October 2008 backup route is the second one. If the PCE that performs the AR computation has the function of WA at the same time, after the computation it will process the WA of the work connection using the alternate routes which belong to primary route at first. After designating the terminal one from the alternate routes of primary route by WA procedure. Sequentially the PCE will select routes from the alternate routes of back up route according to the above strategies. Only these routes can be used to do the WA analysis of the protection connection. After both the WA analyses have been completed, the PCE will return the correct results to the PCC. Another scenario is that the PCE has no fucntion of WA except for the routing computation function. In this case, the PCE should respond the alternate routes of both primary and backup routes to the PCC or to the other PCEs which can perform the related WA process. 5.6. Re-routing of Optimization under AR The sequenced alternate routes that the related PCE responds will be saved by the PCC when the original connection is setting up. When the PCC starts re-routing of optimizing, it can select the optimizing route from these alternate routes. If all the alternate routes can not meet the optimizing strategy, the PCC will request another alternate routes from the PCE, that is, optimizing alternate routes will replace the old ones. The optimizing strategy is the same as the sequence strategy of alternate routes that is introduced in "4.2. AR Extended Constraints". 5.7. Re-routing of Fault Recovery under AR The mechanism of re-routing of fault recovery under AR is basically the same as of re-routing of optimization. The difference is that in re-routing of fault recovery, Control Plane(CP) in WSON will detect the fault location and inform the PCC. The fault type usually consists of link fault, node fault and SRLG fault. And the PCC will add all the detected faults into the exclusion constraints of re- routing. And the selected alternate routes MUST meet the added exclusion constraints when re-routing procedure is performed. 5.8. Hierachical Routing in AR Computation In WSON, especially for AR, hierachical route is also a good mechanism to enhance routing efficiency. By aggregate routes of inter-Autonomous System(AS), inter-area, inter-subarea and so on, the wholly route between the node pair that spans more than one area can be assembled. Similarly, AR computation can be performed at the same range level. To some extent, it is similar to the AR process of Wang, et al. Expires May 1, 2009 [Page 12] Internet-Draft PCECP Extensions of AR for WSON October 2008 inclusion constraint. The path to be set up is separated into a few hierarchies by the different ranges. In the ranges of same hierarchy, alternate routes belonging to different ranges that have been obtained can be combined together by the designated PCE. The whole alternate routes in the ranges of same hierarchy will be include the range border LSRs which the path MUST passes by. If the numbers of alternate routes belonging to different ranges with same hierarchy are respectively k1,k2,kn, the number of whole alternate routes MAY be k1*k2*kn. 6. PCECP Extended Requirements for AR 6.1. Subobject of AR Extended Constraints The body format of constraint route object is mainly based on [RFC4874], [draft-ietf-pce-pcep-xro-06], and [draft-ietf-pce-pecp-16] . Considering inclusion constraint, constraint routing inquiry strategy(strict or loose constraint), and priority of loose constraint, the format has been further improved as following. X In [draft-ietf-pce-pcep-xro-06], the X-bit indicates whether the contraint is mandatory or desired. 0 indicates that the resource specified MUST be excluded from the path computed by the PCE. 1 indicates that the resource specified SHOULD be excluded from the path computed by the PCE. That is, "MUST" means strict constraint, and "SHOULD" means loose constraint. And now, X is extended to indicate whether the exclusion or the inclusion is mandatory or desired. Cons. Type The cons. type of the subobject. The following subobject types are defined. - 00 Exclusion constraint of primary route. - 01 Inclusion constraint of primary route. When the value is 1, the path MUST or SHOULD include the following subobjects. - 02 Exclusion constraint of backup route. - 03 Inclusion constraint of backup route. When the value is 1, the path MUST or SHOULD include the following subobjects. Priority Wang, et al. Expires May 1, 2009 [Page 13] Internet-Draft PCECP Extensions of AR for WSON October 2008 The priority of the subobject. When X subobject is 1, the subobject of priority will take effect. It expresses the priority of loose constraint. The value of priority ranges from 0 to 255 in descending sequence. The higher the priority is, the ealier the loose constraint will be met. Reserved Reserved fields within subobjects MUST be transmitted as zero and SHOULD be ignored on receipt. It is used to pack allignment and extended in the furture. IPv4 prefix Subobject 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |X| Type = 1 | Length | Cons. Type | Priority | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | IPv4 address (4 bytes) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv4 address (continued) | Prefix Length | Attribute | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ IPv6 prefix Subobject 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |X| Type = 2 | Length | Cons. Type | Priority | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | IPv6 address (16 bytes) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 address (continued) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 address (continued) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 address (continued) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 address (continued) | Prefix Length | Attribute | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Unnumbered Interface ID Subobject Wang, et al. Expires May 1, 2009 [Page 14] Internet-Draft PCECP Extensions of AR for WSON October 2008 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |X| Type = 3 | Length | Reserved | Attribute | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Cons. Type | Priority | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TE Router ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Interface ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The TE Router ID and Interface ID fields are as defined in [RFC3477]. Autonomous System Number Subobject 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |X| Type = 4 | Length | Cons. Type | Priority | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | 2-Octet AS Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Note that as in other PCEP objects [PCEP] and RSVP-TE objects [RFC3209], no support for 4-octet AS Numbers is provided. It is anticipated that, as 4-octet AS Numbers become more common, both PCEP and RSVP-TE will be updated in a consistent way to add this support. SRLG Subobject 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |X| Type = 5 | Length | Cons. Type | Priority | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | SRLG Id (4 bytes) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SRLG Id (continued) | Reserved | Attribute | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Wang, et al. Expires May 1, 2009 [Page 15] Internet-Draft PCECP Extensions of AR for WSON October 2008 The Attribute SHOULD be set to two (2) and SHOULD be ignored on receipt. 6.2. Requset of Alternate Routes The format of the RP object body in [draft-ietf-pce-pecp-16] is as follows: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Flags |O|B|R| Pri | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Request-ID-number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | // Optional TLVs // | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ o Flags (24 bits): No Flags are currently defined. o Pri (Priority - 3 bits): the Priority field may be used by the requesting PCC to specify to the PCE the request's priority from 1 to 7. o R (Reoptimization - 1 bit): when set, the requesting PCC specifies that the PCReq message relates to the reoptimization of an existing TE LSP. o B (Bi-directional - 1 bit): when set, the TE LSP is bidirectional. o O (strict/loose - 1 bit): when set, in a PCReq message, this indicates that a loose path is acceptable. o Request-ID-number (32 bits). The Request-ID-number value combined with the source IP address of the PCC and the PCE address uniquely identify the path computation request context. Based on [draft-ietf-pce-pecp-16], the request of alternate routes is extended as following: Wang, et al. Expires May 1, 2009 [Page 16] Internet-Draft PCECP Extensions of AR for WSON October 2008 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Flags |O|B|R| Pri | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Request-ID-number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Primary Routes Number Limit | Backup Routes Number Limit | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Primary Routes Seq Stra. | Backup Routes Seq Stra. | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | // Constraint Subobjects // | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | // Optional TLVs // | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ o O (backup flag - 1 bit): Here, this bit is difined as whether the request asks alternate backup routes computation. o Primary Routes Seq Stra. Please see 4.2.3. Sequence Strategy of Alternate Routes. o Backup Routes Seq Stra. Please see 4.2.3. Sequence Strategy of Alternate Routes. 6.3. Response of Alternate Routes 6.3.1. Basic Information Object 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Isbackupflg | Length | Act num of primary Routes | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Act num of backup Routes | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | // Optional TLVs // | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Isbackupflg: Whether the PCE need to compute backup routes. Wang, et al. Expires May 1, 2009 [Page 17] Internet-Draft PCECP Extensions of AR for WSON October 2008 0 - Backup route disable. 1 - Backup route enable. Length: The length of the basic information object. Act num of primary Routes: Actual number of primary routes computed. Act num of backup Routes: Actual number of primary routes computed. Reserved: For the purpose of extension. Optional TLVs: Now, suggested types are the following. 1 - Complexity of time about primary routes. 2 - Complexity of space about primary routes. 3 - Complexity of time about backup routes. 4 - Complexity of space about backup routes. 6.3.2. Alternate Routes Subobjects In [draft-ietf-pce-pecp-16], it indicates "If the path computation request can be satisfied (the PCE finds a set of paths that satisfy the set of constraints), the set of computed paths specified by means of ERO objects is inserted in the PCRep message." But for AR in WSON, ERO can be obtained only after WA procedure. So alternate routes subobjects are defined as following: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Attribute | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source Hop | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | // Next Hops' Information // | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination Hop | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | // Next Routes // Wang, et al. Expires May 1, 2009 [Page 18] Internet-Draft PCECP Extensions of AR for WSON October 2008 | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Attribute: Primary or backup alternate routes. 0 - Primary alternate routes. 1 - Backup alternate routes. Length: The total length of actual alternate routes. Each hop's information is defined: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Router IPv4 address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Router Node Id | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Output Interface Index | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Hop Metric | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Residual bandwidth | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Hop Subobject Body Format for IPv4 The format of the hop subobject for IPv6 (Object-Type=2) is as follows: Wang, et al. Expires May 1, 2009 [Page 19] Internet-Draft PCECP Extensions of AR for WSON October 2008 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | Router IPv6 address (16 bytes) | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Router Node Id | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Output Interface Index | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Hop Metric | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Residual bandwidth | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Hop Subobject Body Format for IPv6 7. Manageability Considerations Manageability of WSON Alternate Routing (AR) with PCE must address the following considerations: 7.1. Control of Function and Policy In addition to the parameters already listed in Section 4.1, a PCECP implementation SHOULD allow configuring the following PCECP session parameters on a PCC: o The ability to send a WSON AR request. In addition to the parameters already listed in Section 4.1, a PCECP implementation SHOULD allow configuring the following PCECP session parameters on a PCE: o The support for WSON AR. o The attribute of used algorithm for WSON AR. o The support of pre-process for WSON AR. Wang, et al. Expires May 1, 2009 [Page 20] Internet-Draft PCECP Extensions of AR for WSON October 2008 These parameters may be configured as default parameters for any PCECP session the PCECP speaker participates in, or may apply to a specific session with a given PCECP peer or a specific group of sessions with a specific group of PCECP peers. The policy configuration interface is yet to be determined. The interface may be purely a local matter, or it may be supported via a standardized interface (such as a MIB module). 7.2. Information and Data Models It is expected that the operations of AR will be modeled and controlled through appropriate MIB modules. The tables in the new MIB modules will need to reflect the relationships between entities and to control and report on configurable options. Extensions to the PCECP MIB module should be defined, so as to cover the WSON AR information introduced in this document. A future revision of this document will list the information that should be added to the MIB module. 7.3. Liveness Detection and Monitoring Mechanisms defined in this document do not imply any new liveness detection and monitoring requirements in addition to those already described in [RFC4655]. 7.4. Verifying Correct Operation Mechanisms defined in this document do not imply any new verification requirements in addition to those already listed in section 9.4 of [RFC4655]. 7.5. Requirements on Other Protocols and Functional Components The PCE Discovery mechanisms ([ISIS PCED] and [OSPF PCED]) may be used to advertise WSON AR path computation capabilities to PCCs. 7.6. Impact on Network Operation Mechanisms defined in this document do not imply any new network operation requirements in addition to those already listed in section 9.6 of [RFC4655]. 8. Security Considerations This document has no requirement for a change to the security models within GMPLS and associated protocols. But the PCE's AR capabilities Wang, et al. Expires May 1, 2009 [Page 21] Internet-Draft PCECP Extensions of AR for WSON October 2008 may wish to be kept private. Consideration should be given to securing this information. 9. IANA Considerations No new values are specified in this document. 10. Acknowledgments TBD. 11. References 11.1. Normative References [G.694.1] ITU-T Recommendation G.694.1, "Spectral grids for WDM applications: DWDM frequency grid", June 2002. [RFC3471] Berger, L., "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description", RFC 3471, January 2003. [RFC3474] Lin, Z. and D. Pendarakis, "Documentation of IANA assignments for Generalized MultiProtocol Label Switching (GMPLS) Resource Reservation Protocol - Traffic Engineering (RSVP-TE) Usage and Extensions for Automatically Switched Optical Network (ASON)", RFC 3474, March 2003. [RFC4202] Kompella, K. and Y. Rekhter, "Routing Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS)", RFC 4202, October 2005. [RFC4203] Kompella, K. and Y. Rekhter, "OSPF Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS)", RFC 4203, October 2005. [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation Element (PCE)-Based Architecture", RFC 4655, August 2006. [RFC4657] Ash, J. and J. Le Roux, "Path Computation Element (PCE) Communication Protocol Generic Requirements", RFC 4657, September 2006. [RFC4874] Lee, CY., Farrel, A., and S. De Cnodder, "Exclude Routes - Wang, et al. Expires May 1, 2009 [Page 22] Internet-Draft PCECP Extensions of AR for WSON October 2008 Extension to Resource ReserVation Protocol-Traffic Engineering (RSVP-TE)", RFC 4874, April 2007. 11.2. Informative References [LSR-LS] Otani, T., Guo, H., Miyazaki, K., and D. Caviglia, "Generalized Labels of Lambda-Switching Capable Label Switching Routers (LSR)", work in progress: draft-otani-ccamp-gmpls-lambda-labels-01 , November 2007. [PCE-PCEP] Vasseur, JP., Ed, and JL. Le Roux, "Path Computation Element (PCE) Communication Protocol(PCEP)", draft-ietf-pce-pcep-16.txt , November 2007. [PCEP-RE] Oki, E., Takeda, T., and A. Farrel, "Extensions to the Path Computation Element Communication Protocol(PCEP) for Route Exclusions", draft-ietf-pce-pcep-xro-06.txt . [WSON-LC] Zhihong Kang, Zhenyu Wang, and Feng Gao, "Link Connectivity and Common Constraint Information Extension to GMPLS for WDM Switched Optical Networks", draft-lee-pce-wson-routing-wavelength-01 work in progress, November 2007. [WSON-RWA] Lee, Y. and G. Bernstein, "PCEP Requirements and Extensions for WSON Routing and Wavelength Assignment", draft-lee-pce-wson-routing-wavelength-01 work in progress. Authors' Addresses Dajiang Wang ZTE Corporation 12thF, ZTE Plaza, No.19 East HuaYuan Road HaiDian District, Beijing P.R.China Phone: +86-10-82963984 Email: wang.dajiang@zte.com.cn Wang, et al. Expires May 1, 2009 [Page 23] Internet-Draft PCECP Extensions of AR for WSON October 2008 Zhenyu Wang ZTE Corporation 12thF, ZTE Plaza, No.19 East HuaYuan Road HaiDian District, Beijing P.R.China Phone: +86-10-82963987 Email: wang.zhenyu1@zte.com.cn Qimin Xiang ZTE Corporation 5thF, ZTE Industrial Park, No.8 Building NanShan District, Shenzhen P.R.China Phone: +86-755-26773941 Email: xiang.qimin@zte.com.cn Feng Gao ZTE Corporation 12thF, ZTE Plaza, No.19 East HuaYuan Road HaiDian District, Beijing P.R.China Phone: +86-10-82963984 Email: gao.feng1@zte.com.cn Wang, et al. Expires May 1, 2009 [Page 24] Internet-Draft PCECP Extensions of AR for WSON October 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Wang, et al. Expires May 1, 2009 [Page 25]