Internet-Draft Nora Liao document: draft-liao-mpls-ofcl-tsl-00.txt Wei Li Zhengbin Li Peking University, China Expires: June 2005 December 2004 Time Space Label Switching Protocol (TSL-SP) Description for Optical Burst Switched Netwoks Status of this Memo By submitting this Internet-Draft, I certify that any applicable patent or other IPR claims of which I am aware have been disclosed, or will be disclosed, and any of which I become aware will be disclosed, in accordance with RFC 3668. 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. This document may not be modified, and derivative works of it may not be created, except to publish it as an RFC and to translate it into languages other than English. 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. Copyright Notice Copyright (C) The Internet Society (2004). All Rights Reserved. Abstract In this article, we propose a protocol of time-space label switching. First we give the definition to time-space label and time-space label, switched paths, then expatiate on the process of building and removing time-space label switched paths, finally bring forward the resource forecasting scheme and the architecture for OBS Networks, which based on time-space label switched protocol. Nora Liao [Page 1] Internet-Draft TSL-SP November 2004 Table of Contents 1. Introduction.....................................................2 2. Backgrounds......................................................3 3. Label Related Formats............................................4 3.1 Time Label....................................................4 3.2 Space Label...................................................5 3.3 Time Space Label..............................................5 4. Time Space Label Switched Paths..................................6 4.1 Resource Forecast Scheme......................................6 4.2 Routing algorithm.............................................8 4.3 Path Processing...............................................8 5. Architecture for OBS Networks based on TSL-SP....................9 5.1 Logistic Configurations.......................................9 5.2 hysical Configurations........................................9 6. Next Steps......................................................11 7. Conventions.....................................................11 8. References......................................................11 9. Intellectual Property Considerations............................12 10. Authors' Addresses.............................................12 11. Full Copyright Statement.......................................13 Page 2 of 12 1. Introduction Time-space label switching is a new type of switching method, which combines OBS(optical burst switching) with GMPLS (generalized multi-protocol label switching) and supports the self-similitude property of modern network flux and multi-granularity OBS (including wavelength level, waveband level and fiber level etc). Using the thought of optical label in GMPLS for reference, a new method of label, that is time label and space label was brought forward. In this method, time label corresponds to signaling function, while space label corresponds to routing function which is also called addressing function, and consequently the binding of routing and signaling was achieved by time-space label switching. By running time-space label switching protocol in OBS Networks and building time-space label switched paths between a source node and an objective node, resource can be assigned effectively by time and space two dimensions. According to all network state information, routing table is computed by blurry forecasting arithmetic at the entrance of network. OBS Networks based on Time Space Label Switched Protocol adopt double-deck structure which includes controlling plane and transfer plane. The controlling group which assembles time label including the information of burst package occupation of bandwidth, space label including the information of routing and other relative information is forwarded on the controlling plane, it reserves resource for the Nora Liao [Page 2] Internet-Draft TSL-SP November 2004 corresponding data package which comes after a bias-time. Time-space label switching router deals with the controlling group, forwards the label and controls switching module. In this draft, first we introduce the backgrounds and basic concept of time-space label switching, then based on the blurry forecasting of all network resource state we discuss the method of building time-space label switched paths and study how network synchronous precision affects OBS Networks performance. 2. Backgrounds OBS Networks have the characteristics of short last time of linking and paroxysmal operation arrival velocity in time domain, namely, relative to other networks; ingress nodes can make more requests for linking in the same time slot, as illustrated in picture 1a). All call requests arrive at t1 time , however node does not have adequate resources to be assigned., so part of the requests have to wait for an average waiting time Tw until t2 they can be served, consequently the robability of network block becomes higher; at the same time, the cost of organizing networks is higher for needing buffering. If moving part of the requests to time t2 directly, namely, assigning serve slots of each node in routing paths to burst packages by PRI and other factors before source nodes send their requests, not only buffering is no longer needed, but also the rate of request processing is increased, the probability of block is decreased. Time t1,t2,t3 .... when requesting for service should lap over the time when requests arrive at local nodes, so assigning time slot must synthetically consider two factors: first, the time when requests arrive; second, the time when nodes are free. This is the radical mind of time-space label. Define the time t1,t2,t3 .... as time label (as illustrated in picture 1b). Time label assigns service time, flexibly attempers network resource and decreases the probability of network blocking by the requests which are going to arrive at nodes. t1 t2 | request call1 | | | call1 call2 call3 (new) | call4 (new) | ----------------------->| ---------------------->|------------>time | call2 call3 (blocked) | | | | | Figure 1: delay requests for service Nora Liao [Page 3] Internet-Draft TSL-SP November 2004 t1 t2 t3 | | | | request call1 | request call2 | | | | call1 (new) | call2 (new) | call3 (new) | ------------>| ------------>| ------------>|----------------->time | | | | | | Figure 2: time label requests for service In other words, the separation of routing and signaling is also the main reason for network blocking, because it results in resource assigned in one dimension but conflicting in the other dimension. Although we use fiber delay line to deal with the competitive conflicts breaking out in the middle nodes at present, the method is just a makeshift, further more the ameliorative effect is not distinct in high speed optical networks. Therefore, we can not make a radical improvement of network performance unless solve the separation of routing and signaling and achieve the statistical multiplexing of resource. Time-space label switching protocol writes time label - signaling and space label - routing into controlling groups, binds signaling and routing, assigns resource in time and space two dimensions, ends the history of separation of signaling and routing, decreases the probability of network blocking radically. 3. Label Related Formats 3.1 Time Label Define the precise time when burst data packages via routing paths arrive at each node in the link as " time label " T_ijnk , depicted in the following formula : T_ijnk=L_ijnk /v+T_ijni In the formula, T_ijnk(n=1,2,....m represents there are m paths) represents the time when burst packages via marginal network node I passing through the path n selected beforehand arrive at middle node k(k=1,2,...N represents there are N nodes on the path); L_ijnk represents the distance between source node I and the middle node K on the time-space label switched path n; v represents the velocity of light in the fiber, v=c/n, c represents the velocity of light in vacuum, n represents refractive index of fiber; TIJnI represents the time when burst packages are sent from marginal nodes. Nora Liao [Page 4] Internet-Draft TSL-SP November 2004 The time difference when burst packages and controlling group are sent from source nodes is ?T=Tc-Tb , it should be longer or equal to the "bias time" of source node in JET Protocol, namely, ?T=?di (i=1,…N) ( represents the sum of time in which the ith middle node processes controlling group and the time in which optical-switch switches). On account of being lack of optical logic and optical buffering apparatus, once burst packages are sent from source node, the packages will transfer transparently without additive delay in the network (including every node) at velocity of light, hence as long as we confirm the time when burst packages are sent from source node, the "time label" of each node on the path can be exactly predicted. 3.2 Space Label Similar to the method of GMPLS label, we make the nodes on the selected switched paths where burst packages are about to be transferred along with certain attribute of ports on the paths as space label, space label is denoted by Node ID and Port ID in the controlling group respectively. In the network, the input ports and output ports of one node itself are called local ports, while the input and output ports of nearby nodes are called forane ports. Port label can be any granularity port in the optics domain, it includes three essential information: the type of port switching, biggest bandwidth ( how many can be reserved ) and the type of digital coding. Space label makes use of routing information to felicitously distribute space resource. 3.3 Time Space Label The time label and space label of each node on the routing path are included in controlling group in the form of label stack; accordingly form the time-space label. Because of neglecting the time in which burst packages pass the inner of the middle nodes, each middle node in OBS Networks has the same time label of input port and output port. Substantially, time label is a signaling protocol of services assignment function, while space label has the function of routing. Consequently, time-space label has these characteristics: 1. Time-space label must have unique mark in the whole network, so that label information can be distinguished anywhere in the net. 2. The setting of space label requires the topology and state information of the whole network. 3. In the OBS Networks running time-space label switching protocol, we must avoid using photonics storage apparatus, otherwise the function of time label can not be implemented. Nora Liao [Page 5] Internet-Draft TSL-SP November 2004 4. Time label requires synchronous precision in the whole net. Compared with bit and package synchronization, because of the error of net synchronization has been decreased to lower than, all existing network synchronous precisions meet the need of time label. 5. Time-space label can make stack operation. 4. Time Space Label Switched Paths 4.1 Resource Forecast Scheme As far as the marginal nodes of time-space label network are concerned, building time-space label switched paths for burst package switching depends on the state information of whole net. However, on account of the influences of rate of kernel node processing, distance of the transfer of state information and other factors, it is difficult to refresh state information in real-time, so the whole net state information recorded in the marginal nodes is lagged, it isn't synchronous with the information about occupancy of network resource. Hence, if we want to make OBS Networks which based on time-space label compatible with current networks, one of the pivotal problems is how to accurately reserve network resource by using lagged state information in initialization. We introduce blurry subject grade function to study the problem of how to predict resource in the time-space label network. For a blurry data, subject grade indicates the blurry grade of this data.Combined with the characteristics of TSL-SP Protocol, we analyze the factors about how the blurry subject grade of resource state's information can be influenced, these factors are shown as follows: 1. Node's ability of information processing : Processing rate may not catch up with the change of dynamic call if processing ability is weak. 2. Distance of the transfer of state information : the farther the distance between middle node and source node, the higher blurry grade of information is. 3. The rate of refreshment of node's state information : the shorter the period of refreshment and faster of rate, the higher grade of dependence of information is. 4. The historical information of each node stored in the marginal node's entire net state information base. The information on occupation of wavelength which every kernel node sends to the whole net state resource database has only two states, "0" and "1". We define "0" represent free, "1" represent occupied. Therefore according to the historical distribution of "0" and "1" state of each node's wavelength resource in the whole net resource database, we can estimate the busy grade of corresponding wavelength, the probability of going to be occupied. Nora Liao [Page 6] Internet-Draft TSL-SP November 2004 According to the above analysis, we bring forward two strategies for resource prediction. 1. Wavelength Prediction Make distance of the transfer of node state information L, period of refreshment T, busy grade of wavelength P as influencing factors of computing subject grade. The period of refreshment of node state is a random variable, the average period ? and variance di of refreshment are computed by statistics. Compute the correctional factor e (0