Internet Draft Network Working Group Jin Ho Hahm Internet-Draft ETRI Kwang-il Lee Expiration Date: June 2001 NIST December 2000 Bandwidth Provisioning and Restoration Mechanisms in Optical Networks <draft-hahm-optical-restoration-01.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 mechanisms proposed use a 1:N restoration scheme, preparing backup lightpaths in advance, before failures occur. Hahm et al [Page 1] draft-hahm-optical-restoration-01.txt December 2000 1. Introduction In general, Internet backbone networks are overbuilt in comparison to average traffic volumes, in order to support fluctuations in traffic levels and to stay ahead of traffic growth rates. Therefore, any given time there are typically under utilized capacity in deployed network facilities. 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 repaired as soon as possible. Today's SONET networks can achieve recovery times of 50msec, but depend on 1+1 backup network resources to do so. 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 meet 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 the Internet-Draft[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, because 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. Hahm et al [Page 2] draft-hahm-optical-restoration-01.txt December 2000 Based on these commands, a chain of connections through OXCs can form an end-to-end lightpath. The OXC starting a lightpath is called the ingress OXC, and the OXC ending a lightpath is called the egress OXC. The OXCs inside the lightpath are called the intermediate OXCs. An OXC fabric receives commands from the OSC, and replies whether the 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 Lightpath selection can be calculated based on dynamic measurements Hahm et al [Page 3] draft-hahm-optical-restoration-01.txt December 2000 of optical resources that are distributed using link state routing protocols. Many 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. The minimum link state information required to select lightpaths is as follows: the information of lambda availability in each link, the number of unused incoming data ports and unused outgoing data ports at each OXC. Because the route of a lightpath is decided at the ingress OXC, the number of unused incoming data ports of the ingress OXC can be obtained without explicit LSA exchange. However, the number of unused outgoing data ports of each OXC has to be distributed. Every ingress OXC 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 OXC 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 assumed that network management functions will perform lightpath selection. Therefore, in this Draft we only consider the signaling procedures after the route of the lightpath has been determined. 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. However, 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. In this Draft, the ingress OXC is in charge of the creation, deletion, and restoration of lightpaths. o Detection of damaged lightpaths If an optical link is damaged physically, all the lightpaths passing Hahm et al [Page 4] draft-hahm-optical-restoration-01.txt December 2000 through this link will 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 by loss of light alarm. However because the egress OXC receives the light signal and converts it back to an electrical signal, any 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, strict explicit routing is preferred to designate the lightpath. By using strict 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 additional failures to other lightpaths in the same restoration group. This defect could be remedied through a M:N restoration mechanism (M >= 2). Such a mechanism could be supported through the scheme described here, but will not be considered further 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 Hahm et al [Page 5] draft-hahm-optical-restoration-01.txt December 2000 that the backup lightpath has no connections between the data port and lambda port in the ingress OXC and egress OXC, whereas the primary lightpath has connection in both OXCs. The connections between these ports are made during the restoration process. o Release of damaged lightpath A damaged lightpath must be released in order to make the resources of its undamaged segments available for future demands. 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 can be transmitted with some delay 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 a minimal 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 OXCs 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 lightpaths, the reporting procedure Hahm et al [Page 6] draft-hahm-optical-restoration-01.txt December 2000 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 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 transferred by 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 transmits the 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 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 apply the increased bandwidth to the generation 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 Hahm et al [Page 7] draft-hahm-optical-restoration-01.txt December 2000 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. 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 outgoing lambda port in the ingress OXC. 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 shared by the same restoration group. First of all, the ingress OSC 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 that of backup lightpath. This process is executed internally without exchanging messages. As the second step, the ingress OXC sends the Lightpath Restoration Message. This message has the backup lightpath ID and the egress OXC identifier. When the egress OXC receives this message, the OSC of egress OXC finds the outgoing data port for damaged lightpath, and converts this message into the control command and sends it to OXC switch fabric to connect between the incoming lambda port and the outgoing data port in OXC switch fabric. The OXC switch fabric returns a result status to the OSC. Then the egress OXC of OSC Hahm et al [Page 8] draft-hahm-optical-restoration-01.txt December 2000 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. This procedure is carried out according to the procedure of section 4.1.2. 4.3.2 Restoration procedure for damaged 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 a lightpath can take place for several reasons: (1) the primary or backup lightpath becoming impaired by the damage, (2) the primary lightpath becoming underutilized due to a decreased volume of the data traffic, (3) the backup lightpath becoming unneeded 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. A Lightpath Release Message is transmitted to the egress OXC or to the intermediate OXC which occurred a failure. For this process, the Lightpath Release Message contains 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 transmits the Lightpath Release Message to the next adjacent intermediate OXC. During this procedure, intermediate OXCs recycle the network resources, then update their link state information. This link state information will then be distributed to other OXCs using OSPF/IS-IS link state distribution procedures. If the Lightpath Release Message successfully proceeds all the way to the egress OXC, the egress OXC notifies the successful result to the ingress OXC by the Lightpath Notification Message. The ingress OXC receiving the notification message announces the decrement of bandwidth capacity through OSPF/IS-IS announcements. Once this new resource information has propagated through the IGP, the Hahm et al [Page 9] draft-hahm-optical-restoration-01.txt December 2000 corresponding link resources can be used in later path selection/ establishment function. If the intermediate OXC receiving the Lightpath Release Message fails to affect the release in the OXC switch fabric, an error message is returned to the OSC and subsequently propagated back 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. These message types are defined by extending CR-LDP. 5.1 Lightpath Setup Message A Lightpath Setup Message is issued to create a 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Lightpath OXC list TLV | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Egress OXC identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - Message ID The message identifier of this message, which is incremented by one whenever a new message is generated by an ingress OXC, regardless the generated message type. It is used to specify the message issued by the ingress OXC to create the lightpath. - Ingress OXC identifier The address of the 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-01.txt December 2000 - OXC Outgoing Lambda Port ID This represents an ID of outgoing lambda port from which the lightpath starts. The value of { Ingress OXC identifier + B + OXC outgoing lambda Port ID } is unique throughout 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. 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 generated by the ingress OXC. This ID is used to identify the original messages respectively. - Returned OXC identifier The 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 lambda port does not exist in the designated intermediate OXC. Hahm et al [Page 11] draft-hahm-optical-restoration-01.txt December 2000 3: The outgoing data port does not exist in the designated egress OXC. 4: The lambda switching function does not exist in OXC. 5: The lambda conversion function does not exist in OXC. 6: The outgoing data port of the designated OXC is used by another primary lightpath. 7: The release of designated lightpath was failed. 8: The restoration of designated lightpath was failed. 9: 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 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 message issued by egress OXC to inform the damaged lightpath. - Lightpath ID { Ingress OXC identifier + B + OXC outgoing lambda Port ID } 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 Hahm et al [Page 12] draft-hahm-optical-restoration-01.txt December 2000 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| OXC Outgoing Lambda Port ID (backup) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Egress OXC Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - 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 + OXC Outgoing Lambda Port ID } is used to specify the backup lightpath - Egress OXC Identifier Address of Egress OXC which detects the damage of a lightpath 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 | Hahm et al [Page 13] draft-hahm-optical-restoration-01.txt December 2000 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |B| OXC Outgoing Lambda Port ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Lightpath OXC list TLV | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Egress OXC identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - 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 OXC identifier + B + OXC outgoing lambda port ID} 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 address of the OXC at which a lightpath ends. 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 sequence of 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |x| OXC Outgoing Lambda Port ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | . . . . . . | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | . . . . . . | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OXC Identifier #n | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Hahm et al [Page 14] draft-hahm-optical-restoration-01.txt December 2000 |x| OXC Outgoing Lambda Port ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - OXC Identifier It is used to identify intermediate OXCs through which a lightpath passes. - OXC Outgoing Lambda Port ID It is used to identify an outgoing lambda port Security Considerations It is important to maintain secure communication between the OXCs. However, this Draft 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 [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 Hahm et al [Page 15] draft-hahm-optical-restoration-01.txt December 2000 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]