Internet Engineering Task Group Jin Ho Hahm Internet-Draft ETRI Kwang-il Lee Expiration Date: May 2001 NIST November 2000 Bandwidth Provisioning and Restoration Mechanisms in Optical Networks draft-hahm-optical-restoration-00.txt Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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/lid-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 (2000). All Rights Reserved. Abstract With the advent of tunable lasers and optical switches, dynamic configuration of optical networks has become possible. This Internet-Draft presents a signaling mechanism for bandwidth provisioning and restoration based on this dynamic configuration of optical networks. The mechanism adopted uses a 1:N restoration scheme, preparing the backup lightpath in advance before failures occur. 1. Introduction Hahm et al [Page 1] draft-hahm-optical-restoration-00.txt November 2000 In general, Internet backbone networks are overbuilt in comparison to average traffic volumes, in order to support fluctuations in traffic levels. Therefore, constructed network facilities are in a sense wasted most of the time. One of the most important concepts in network management is maintaining the survivability of networks. When there are link failures or the like, any affected routes should be replaced with functioning ones as soon as possible. SONET can achieve this, with a guaranteed short recovery time of 50msec, but is wasteful because it requires 1:1 backup network resources. If instead an adaptive 1:N restoration mechanism can be applied, network survivability can still be enhanced while minimizing the waste in network resources. This Internet Draft proposes a mechanism for bandwidth provisioning and restoration processes which meets this goal, and defines the associated signaling and message types. 2. Basic concept for bandwidth provisioning and restoration This section describes the basic concept of bandwidth provisioning and restoration mechanisms in optical networks. o OXC system architecture The OXC system architecture for lambda switching has been introduced in several Internet-Drafts[1]. Our proposed bandwidth provisioning and restoration mechanisms are based on this architecture. The internal processing in OXC system for lambda switching is briefly outlined here. This is presented only as an aid to understanding, as other basic mechanisms would also suffice. An Optical Crossconnect (OXC) has several incoming and outgoing lambda ports, connected to adjacent OXCs, and several incoming and outgoing data ports attached to a controlling router. An OXC has an OXC Switching Controller (OSC) and OXC switch fabric. The OSC converts the received messages (mentioned in section 5) to the proper control command, and sends this command to the OXC fabric. The commands to control the OXC fabric are as follows: connect (and disconnect) between an incoming lambda port and outgoing lambda port; connect (and disconnect) between an incoming lambda port and outgoing data port; connect (and disconnect) between an incoming data port and an outgoing lambda port. Based on these commands, a chain of connections through OXCs can be formed, the lightpath. The OXC starting a lightpath is called the ingress OXC, and the OXC ending a lightpath is called the egress OXC. The OXC inside the lightpath are called the intermediate OXC. An OXC fabric receives commands from the OSC, and replies whether the Hahm et al [Page 2] draft-hahm-optical-restoration-00.txt November 2000 command was successful or not. The OSC then converts the result into the form of a message (described in section 5) to send to the counter OSC through the network. +---------+ | | +-----------------------+ | IP | | | | Network | | Router | | | | | +---------+ +--+--+--+-----+--+--+--+ A A A A | | | | | | | | | | | | | | | | | +----|----------|--|--|-----|--|--|---------+ | V | | | | | | | | +-----+ | | | | | | | | | OSC |<--+ | | | | | | OXC | | +-----+ | | | | | | | | | +-V---|--|--|-----|--|--|-----+ | | | | | | V V V | | outgoing data port O O O O O O incoming data port | | | | | | | -->>-----------------O-----+ | +--O--------------->>-- -->>-----------------O-------------\ +-----O--------------->>-- -->>-----------------O \--------O--------------->>-- -->>-----------------O-----------------------O--------------->>-- incoming lambda | port OXC Fabric port | outgoing lambda | +-----------------------------+ | | | +-------------------------------------------+ (Fig.1) OXC system architecture o Control channel between OXC switching controllers This Draft assumes that control channels between OSCs must be maintained to exchange signaling information. The details of the mechanisms required are outside the scope of the Draft. o Gathering of link state information for lightpath computation The best route for lightpaths can be calculated based on link state information of optical resources, which varies dynamically in optical networks. Many useful mechanisms for exchanging the link state information have been introduced by extending existing routing protocol such as OSPF or IS-IS LSA[2,3,4,5,6] in the optical network environment. This Draft assumes these link state information exchange mechanisms. Hahm et al [Page 3] draft-hahm-optical-restoration-00.txt November 2000 The minimum link state information required to decide lightpaths is as follows: unused lambdas in links, unused output data ports in ingress routers, and unused input data ports in egress routers. Because the route of a lightpath is decided at the ingress router, the status of output data ports of the ingress router can be obtained without explicit LSA exchange. However, the status of input data ports of each router has to be distributed. Every ingress router has to know the SRLG (Shared Risk Link Group) value of every link to compute lightpaths which do not share the same risk of potential damages. These SRLG values do not change, and so this information is exchanged only once. In order to know whether to connect between incoming lambdas and outgoing lambdas of different wavelengths, the ingress router has to know the availability of lambda converters in all OXCs. Currently, this Draft simply assumes that all OXCs have enough lambda converters. o Triggering of lightpath generation It is determined by network management functions what lightpaths are generated, from which ingress OXC, through which intermediate OXCs, to which egress OXC. Therefore, in this Draft we only consider the signaling procedure after determining the route of the lightpath. In general the establishment of an LSP in MPLS can be divided into two cases: pre-establishment before data traffic arrives at the ingress router, and post-establishment after data traffic arrives at the ingress router. In the latter case, LSPs must be created quickly enough to handle the data traffic waiting at the ingress router for transmission. The creation of lightpath will not in general be so time-critical, as they will only be created in response to long-term changes in traffic volume. Since the number of lightpaths being created per unit time is so much less than the number of LSPs in MPLS, the scalability of lightpath management is much higher than MPLS. The ingress OXC is in charge of the creation, deletion, and restoration of lightpaths. o Detection of damaged lightpaths If some optical link is damaged physically, all the lightpaths passing through this link must be affected. Generally in case of an all-optical network not using optical/electrical/optical(OEO) conversion, damage to a lightpath or drop of light signal level cannot be easily detected. However because the egress OXC receives the light signal and converts it back to an electrical signal, any Hahm et al [Page 4] draft-hahm-optical-restoration-00.txt November 2000 problems arising with the lightpath can be detected there. Therefore the responsibility for the detection of damaged lightpaths lies with the egress OXC. o Strict explicit routing vs. loose explicit routing In CR-LDP, both strict explicit routing and loose explicit routing mechanisms may be used. However, in this scheme for lambda switching, only strict explicit routing is preferred to designate the lightpath. By using strictly explicit routing, optical network resources can be managed more precisely, and the rate of success for lightpath creation can be enhanced. o Decision of backup lightpath In this Draft, we adopt the method of pre-establishment of backup lightpaths in advance of link failure. This minimizes the restoration time, especially when the restoration process must be carried out simultaneously for a large number of damaged lightpaths sharing the same damaged link. In this Draft, we choose the 1:N restoration mechanism, where N primary lightpaths share one backup lightpath. The size of N will depend on the topological characteristics of the network. We say that the N primary lightpath and one backup lightpath share the same restoration group. The weakness of the 1:N restoration mechanism is that, after an initial failure and before reprovisioning, it cannot support restoration for subsequent failures to other lightpaths in the same restoration group. This defect could be remedied at the expense of greater complexity through a 2 (or more):N restoration mechanism. Such a mechanism could be supported through the scheme described here, but will not be further considered at this time. To decide on the grouping of primary lightpaths and backup lightpath, the SRLG values of links are considered. Because a lightpath travels through several links, it will have corresponding to it the set of SRLG values of its member links. The lightpaths within a restoration group cannot share the same set of SRLG value, as then a single failure could affect several lightpaths simultaneously. Therefore, when a new lightpath is created, if it cannot be placed within any existing restoration group, a new restoration group is created, along with a backup lightpath for the newly created primary lightpath. The difference between a primary lightpath and backup lightpath is that the backup lightpath has no connections between the data port and lambda port in the OXCs of the ingress router and egress router, whereas the primary lightpath has both of them. The connections between these ports are made during the restoration process. Hahm et al [Page 5] draft-hahm-optical-restoration-00.txt November 2000 o Release of damaged lightpath A damaged lightpath must be released in order to make its (undamaged) resources available to newly created lightpaths. The release of lightpath resources is the ingress OXC's responsibility. The released resources can be reused after announcement of their released status via OSPF or IS-IS LSAs. o Failure of lightpath creation The creation of lightpaths can fail for the following three reasons. First, failure can occur due to an inconsistency between the gathered link state information at the ingress OXC and the actual link status of optical network. Because link state information is only transmitted periodically from every OXC, delayed updates can make for this inconsistency. Secondly, failure can occur even if link state information is consistent with the actual link status. If two ingress OXCs decide simultaneously to use the same network resources, one of the lightpath setup attempts will fail because its resources have already been claimed by the other lightpath. Finally, even if lightpath establishment completes, the lightpath may fail to carry data because the quality of transmission does not reach the threshold level. The deterioration of transmission quality can occur due to several reasons[7,8]. The first two cases of failure during lightpath setup are reported to the ingress OXC by a lightpath notification message from the intermediate OXC where the error is noted. Failure of the last sort can be detected by measuring the SNR of the received optical signal, or the error ratio of Optical-to-Electric transformed data. If the quality of the lightpath does not reach the threshold level, the lightpath is released, and a new lightpath is created. 4. Procedures for bandwidth provisioning and restoration In this section, the procedures for bandwidth provisioning and restoration are described in detail, which include the setup procedures for primary and backup lightpath, the reporting procedure for handling damaged lightpaths, the restoration procedure for replacing a damaged lightpath with the backup lightpath, and the release procedure for unused lightpaths. 4.1 Decision of lightpath based on link state information Hahm et al [Page 6] draft-hahm-optical-restoration-00.txt November 2000 If the primary lightpath cannot be created within an existing restoration group, after creating a new restoration group, the primary lightpath and backup lightpath are created within the newly created restoration group. If the primary lightpath can be created within an existing restoration group, no new backup lightpath needs to be created, so the primary lightpath only is created. 4.1.1 Lightpath setup procedure for primary lightpath Once the route of a lightpath is decided, the ingress OXC sends the Lightpath Setup Message to the next intermediate OXC through the control channel. The sequence of intermediate OXCs and the lambdas to be allocated for the lightpath are stored in the lightpath setup message. An intermediate OXC receives the lightpath setup message from its adjacent OXC. The OSC of the intermediate OXC then attempts to configure the OXC switch fabric according to the lightpath setup message, and receives the result from the OXC switch fabric. If a successful result is returned, the OSC of the intermediate OXC then removes its OXC identifier from the lightpath setup message, and then transmits the modified lightpath setup message to the next adjacent intermediate OXC. During this procedure, intermediate OXCs consume the network resources and therefore update the link state information. This link state information will then be distributed to other OXC at the next period by using OSPF or IS-IS LSAs. If a lightpath setup message successfully reaches the egress OXC, the egress OXC then returns the lightpath notification message noting the successful lightpath creation to the ingress OXC. Upon receiving this notification message, the ingress OXC announces this increment in available bandwidth capacity by using OSPF or IS-IS LSA functions at the IP level. Routers receiving this link status information can then apply the increased bandwidth to provisioning of LSPs meeting traffic engineering requirements. If an intermediate OXC receiving the lightpath setup message cannot successfully configure the OXC switch fabric, the intermediate OXC replies with a lightpath notification message indicating the failure to the ingress OXC. An ingress OXC receiving this reply then sends a lightpath release message to release any tentatively claimed resources. The detailed procedure is explained in section 4.3. The primary lightpath made by this procedure has a lightpath ID comprising the ingress OXC identifier, a B flag value of 0 indicating that this lightpath is a primary lightpath, and the outgoing lambda port in the ingress OXC. This lightpath ID is then used to identify the lightpath in subsequent messages related to lightpath failure, restoration, and release. Hahm et al [Page 7] draft-hahm-optical-restoration-00.txt November 2000 4.1.2 Lightpath setup procedure for backup lightpath Backup lightpaths are created through the same procedure as primary lightpaths. The backup lightpath made by this procedure has a lightpath ID comprising the ingress OXC identifier, a B flag value of 1 indicating that this lightpath is a backup lightpath, and the sequence number issued by the ingress OXC. This lightpath ID is then similarly used to indicate the lightpath in subsequent messages. 4.2 Procedure for reporting a damaged lightpath Damage to lightpaths can be detected by the egress OXC. After detection, the egress OXC issues a lightpath failure message as soon as possible. The lightpath failure message comprises the ID of the damaged primary or backup lightpath, and the reason why the impairment occurred. 4.3 Restoration procedure Restoration can be applied to a damaged primary lightpath or backup lightpath. 4.3.1 Restoration procedure for damaged primary lightpath In case of failure of a primary lightpath, the ingress OXC is made aware of which lightpath is damaged by the lightpath ID in the failure message. The ingress OXC then replaces the damaged primary lightpath with the backup lightpath sharing the same restoration group. First of all, the ingress OXC repairs the connection within its own OXC by replacing the connection between the incoming data port and outgoing lambda port of the damaged lightpath with the connection between the incoming data port and outgoing lambda port of the backup lightpath. This process is executed internally without exchanging messages. As the second step, the ingress OXC issues the lightpath restoration message. This message has the information of the egress OXC identifier and the OXC outgoing data port ID to be connected to backup lightpath. If the egress OXC receives this message, the OSC of egress OXC converts this message into the control command to control the connection in OXC switch fabric, and sends this control to OXC switch fabric. The OXC switch fabric responses the executed result to the OSC, and the egress OXC of OSC reflects the result to the lightpath notification message, and sends this message to the ingress OXC. Because the backup lightpath is consumed by this restoration procedure, the new alternative backup lightpath must be created. Hahm et al [Page 8] draft-hahm-optical-restoration-00.txt November 2000 This procedure is carried out after the procedure of section 4.1.2. 4.3.2 Restoration procedure for damaged backup lightpath In case of failure of backup lightpath, ingress OXC can be aware which lightpath is damaged by referring the lightpath ID of the backup lightpath. The damage of the backup lightpath does not affect to the ongoing data transfer. However, because the primary lightpaths belonging to the same restoration group lose the restoration capability, the alternative backup lightpath must be created as soon as possible. The procedure for creating alternative backup lightpath is processed according to the procedure of section 4.1.2. 4.4 Lightpath release procedure for lightpath The release of lightpath takes place against the following lightpaths: (1) the primary or backup lightpath impaired due to the damage, (2) the primary lightpath that is not used any longer due to the decreased volume of the data traffic, (3) the backup lightpath becoming useless due to the release of all primary lightpaths sharing the same restoration group, (4) the primary or backup lightpath that is not proceed its lightpath further due to the occurrence of the error during the lightpath setup procedure. The lightpath release message is transmitted to the egress OXC or the intermediate OXC from the ingress OXC passing through the intermediate OXCs comprising the target lightpath. In order to do this processing, the lightpath release message has the information of the sequence of intermediate OXCs that it has to travel and the lambdas to be de-allocated. An intermediate OXC receives the lightpath release message from its adjacent OXC. The OSC of the intermediate OXC then attempts to configure the OXC switch fabric according to the lightpath release message, and receives the result from the OXC switch fabric. If a successful result is returned, the OSC of the intermediate OXC then removes its OXC identifier from the lightpath release message, and then transmits the modified lightpath release message to the next adjacent intermediate OXC. During this procedure, intermediate OXCs bring back the network resources and therefore update the link state information. This link state information will then be distributed to other OXC at the next period by using OSPF or IS-IS LSAs. If finally the lightpath release message is proceeded to the egress OXC with success, the egress OXC replies the successful release to the ingress OXC by the lightpath notification message, and the ingress OXC receiving the notification message announces the decrement of bandwidth capacity by using OSPF or IS-IS LSA function at the IP level. The routers receiving this link status information Hahm et al [Page 9] draft-hahm-optical-restoration-00.txt November 2000 apply the increased bandwidth to the allocation of LSP considering the traffic engineering requirement. If the intermediate OXC receiving the lightpath release message fails to control of the OXC switch fabric, it receives the response of failure from OXC switch fabric, the intermediate OXC replies the error and the reason why failure occurs to the ingress OXC by using the lightpath notification message. 5. Message Types In this section, we define the message types which are used for the bandwidth provisioning and restoration procedures. 5.1 Lightpath Setup Message Lightpath Setup message is issued to create primary lightpath or backup lightpath by an ingress OXC. This message is forwarded to the next intermediate OXC through a control channel on the hop by hop basis. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| Lightpath Setup | Message Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Ingress OXC identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |B| OXC Outgoing Lambda Port ID (pri) or Sequence Number(bak) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Lightpath OXC list TLV | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Egress OXC identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OXC Outgoing Data Port ID (primary) or Null (backup) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - Message ID The message identifier of this message, which is incremented by one whenever a new message is generated by this ingress OXC, regardless the generated message type. It is used to specify the message issued by ingress OXC to create the lightpath. - Ingress OXC identifier The address of ingress OXC at which a lightpath starts. - B If the created lightpath is a backup lightpath, B is set to 1. Otherwise(a primary path), it is set to 0. Hahm et al [Page 10] draft-hahm-optical-restoration-00.txt November 2000 - OXC Outgoing Lambda Port ID If the created lightpath is a primary lightpath, this represents an ID of outgoing lambda port from which the lightpath starts. - Sequence Number If the created lightpath is a backup lightpath, it is used to identify the lightpath. In general, this value is increased by one whenever it is issued by ingress OXC. If the increased value is the same as the one that is still used for a existing backup lightpath, the sequence number increased again to the next higher value. The value of { Ingress OXC identifier + B + OXC outgoing lambda Port ID | Sequence Number } is unique through out the optical network. Therefore, this combined value is used to specify the lightpath. - Lightpath OXC list TLV It represents the sequence of OXCs comprising lightpath and lambdas being allocated for a lightpath. - Egress OXC Identifier The identifier of the OXC at which the lightpath ends. - OXC Outgoing Data Port ID If the lightpath is a primary lightpath (B=0), this field is filled by outgoing data port ID. Otherwise (B=1), this field is set to zero. 5.2 Lightpath Notification Message This message is used as the response message for the Lightpath Setup Message, the Lightpath Restoration Message, and the Lightpath Release Message. An ingress OXC identifies a response message respectively by comparing the Message ID conveyed by a notification message with the Message ID which was issued by itself. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| Lightpath Notify | Message Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Returned OXC identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Result | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - Message ID This message ID is the return value of the message ID which is Hahm et al [Page 11] draft-hahm-optical-restoration-00.txt November 2000 generated by ingress OXC. This ID is used to identify the original message respectively. - Returned OXC identifier The IP address of the intermediate OXC or egress OXC which issued this Notification message. - Result 0: The message which was issued by an ingress OXC is processed successfully 1: The designated intermediate OXC does not exist 2: The designated fiber does not exist in the designated intermediate OXC 3: The designated lambda does not exist in the designated intermediate OXC 4: The outgoing Data port does not exist in the designated egress OXC 5: The lambda switching function does not exist in OXC 6: The lambda conversion function does not exist in OXC 7: The outgoing data port of the designated OXC is used by another primary lightpath 8: The release of designated lightpath was failed 9: The restoration of designated lightpath was failed 10: Error occurred by an unspecified reason 5.3 Lightpath Failure Message This message is generated by an egress OXC to notify error status of a lightpath. The ingress OXC can identify which lightpath is under malfunction by the lightpath ID of this message. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| Lightpath Failure | Message Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Ingress OXC Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |B| OXC Outgoing Lambda Port ID (pri) or Sequence Number(bak) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Egress OXC Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Result | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - Message ID The message identifier of this message, which is incremented by one whenever a new message is generated by this egress OXC, regardless the generated message type. It is used to specify the Hahm et al [Page 12] draft-hahm-optical-restoration-00.txt November 2000 message issued by egress OXC to inform the damaged lightpath. - Lightpath ID { Ingress OXC identifier + B + OXC outgoing lambda Port ID | Sequence Number } is used to specify the lightpath - Egress OXC Identifier Address of Egress OXC which detected the damage of a lightpath - Result 1: Signal of light was disappeared 2: Signal level of light was degraded 3: Error rate of transmitted data exceeded threshold level 4: Error occurs with an unspecified reason 5.4 Lightpath Restoration Message This message is sent to an egress OXC by an ingress OXC to restore a damaged primary lightpath or damaged backup lightpath. When an ingress OXC receives the lightpath failure message from egress OXC, it issues this message. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| Lightpath Restore | Message Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Ingress OXC Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1| Sequence Number (backup) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Egress OXC Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OXC Outgoing Data Port ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - Message ID The message identifier of this message, which is incremented by one whenever a new message is generated by this ingress OXC, regardless the generated message type. It is used to specify the message issued by ingress OXC to restore the damaged lightpath. - Lightpath ID { Ingress OXC identifier + 1 + Sequence Number } is used to specify the backup lightpath - Egress OXC Identifier Address of Egress OXC which detects the damage of a lightpath Hahm et al [Page 13] draft-hahm-optical-restoration-00.txt November 2000 - OXC Outgoing Data Port ID It is the port ID in egress OXC to which a backup lightpath is connected. 5.5 Lightpath Release Message This message is used to release the established primary lightpath or backup lightpath. If the intermediate OXCs or egress OXC receive this message, they release the lambda or outgoing data port resources. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| Lightpath Release | Message Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Ingress OXC identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |B| OXC Outgoing Lambda Port ID (pri) or Sequence Number(bak) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Lightpath OXC list TLV | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Egress OXC identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OXC Outgoing Data Port ID (primary) or Null (backup) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - Message ID The message identifier of this message, which is incremented by one whenever a new message is generated by this ingress OXC, regardless the generated message type. It is used to specify the message issued by ingress OXC to release the pre-occupied lightpath. - Lightpath Identifier {Ingress Router IP Address + B + Router Output Port ID | Sequence Number} is used to identify the primary lightpath or backup lightpath which is released by an ingress OXC - Lightpath OXC list TLV Represents the sequence of OXCs comprising released lightpath and lambdas being allocated for a lightpath - Egress OXC Identifier The identifier of the OXC at which a lightpath ends. - OXC Outgoing Data Port ID If the lightpath is a primary lightpath (B=0), this field is filled by outgoing data port ID. Otherwise (B=1), this field is Hahm et al [Page 14] draft-hahm-optical-restoration-00.txt November 2000 set to zero. 5.6 Lightpath OXC List TLV This TLV is used to specify a sequence of the OXCs which are connected by optical links and lambdas. This TLV is used with the Lightpath Setup Message and Lightpath Release Message. The listed OXCs is listed from the nearest OXC to the farthest OXC. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| Type(= Lightpath OXC list) | Length = 8 * n | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OXC Identifier #1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Outgoing Fiber ID | Outgoing Lambda ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | . . . . . . | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | . . . . . . | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OXC Identifier #n | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Outgoing Fiber ID | Outgoing Lambda ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - OXC Identifier It is used to identify a OXC that lies on the lightpath - Outgoing Fiber ID It is used to identify an outgoing fiber from the specified OXC - Outgoing Lambda ID It is used to designate a lambda assigned to the specified fiber Security Considerations It is of course essential to maintain secure communication between the OXCs. However, this document does not address the detailed security consideration. It is reserved for future study. References [1] Daniel O. Awduche, Yakov Rekhter, John Drake, and Rob Coltun, "Multi-Protocol Lambda Switching: Combining MPLS Traffic Engineering Control with Optical Crossconnect," Internet Draft, Work in Progress, November 1999 Hahm et al [Page 15] draft-hahm-optical-restoration-00.txt November 2000 [2] Kireeti Kompella et al, "Extensions to IS-IS/OSPF and RSVP in support of MPL(ambda)S," Internet Draft, Work in Progress, February,2000 [3] S. Giacalone, "Network Engineering Extensions (NEXT) for OSPFv3," Internet Draft, Work in Progress, August 2000 [4] G. Wang et al, "Extensions to OSPF/IS-IS for Optical Routing," Internet Draft, Work in Progress, March 2000 [5] K. Kompella et al, "IS-IS Extensions in Support of MPL(ambda)S," Internet Draft, Work in Progress, July 2000 [6] K. Kompella et al, "OSPF Extensions in Support of MPL(ambda)S," Internet Draft, Work in Progress, July 2000 [7] Angela Chiu and John Strand, "Unique Features and requirements for the Optical Layer Control Plane," Internet Draft, Work in Progress, July 2000 [8] L. Ceuppens, D. Blumenthal, J. Drake, J. Chrostowski, and W. Edwards, "Performance Monitoring in Photonic Networks in support of MPL(ambda)S," Internet Draft, Work in Progress, March 2000 Acknowledge This work has been produced from the joint project between ETRI (Electronics and Telecommunications Research Institute in Korea) and NIST (National Institute Standards and Technology). Author's Address Jin Ho Hahm ETRI 820 West Diamond Avenue Gaithersburg, MD 20899 Phone: 301-975-8400 Email: hahm@antd.nist.gov & jhhahm@etri.re.kr Kwang-il Lee NIST 820 West Diamond Avenue Gaithersburg, MD 20899 Phone: 301-975-8428 Email: kilee@antd.nist.gov Hahm et al [Page 16]