WO2009087400A1 - Système de communications mpls et aspects apparentés - Google Patents

Système de communications mpls et aspects apparentés Download PDF

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Publication number
WO2009087400A1
WO2009087400A1 PCT/GB2009/000069 GB2009000069W WO2009087400A1 WO 2009087400 A1 WO2009087400 A1 WO 2009087400A1 GB 2009000069 W GB2009000069 W GB 2009000069W WO 2009087400 A1 WO2009087400 A1 WO 2009087400A1
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WIPO (PCT)
Prior art keywords
protocol label
network
label switching
field
mpls
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PCT/GB2009/000069
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English (en)
Inventor
Neil Harrison
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British Telecommunications Public Limited Company
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Publication date
Priority claimed from EP08250086A external-priority patent/EP2079188A1/fr
Priority claimed from EP08250094A external-priority patent/EP2079189A1/fr
Application filed by British Telecommunications Public Limited Company filed Critical British Telecommunications Public Limited Company
Publication of WO2009087400A1 publication Critical patent/WO2009087400A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L41/00—Arrangements for maintenance, administration or management of data switching networks, e.g. of packet switching networks
    • H04L41/50—Network service management, e.g. ensuring proper service fulfilment according to agreements
    • H04L41/5077—Network service management, e.g. ensuring proper service fulfilment according to agreements wherein the managed service relates to simple transport services, i.e. providing only network infrastructure
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L41/00—Arrangements for maintenance, administration or management of data switching networks, e.g. of packet switching networks
    • H04L41/34—Signalling channels for network management communication
    • H04L41/344—Out-of-band transfers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L41/00—Arrangements for maintenance, administration or management of data switching networks, e.g. of packet switching networks
    • H04L41/50—Network service management, e.g. ensuring proper service fulfilment according to agreements
    • H04L41/5003—Managing SLA; Interaction between SLA and QoS

Definitions

  • the present invention relates to a multi-protocol label switched (MPLS) communications system and to related aspects thereof.
  • MPLS multi-protocol label switched
  • the invention relates to an MPLS communications system comprising an MPLS data plane communications network and an adjunct control plane (and/or management plane) MPLS network in which, in the MPLS data plane communications network, an MPLS traffic unit contains an OAM field in its header to indicate it relates to an OAM function.
  • the value of the OAM field acts as a flag which distinguishes client traffic from OAM traffic in the MPLS data plane network, i.e., in-band OAM is implemented.
  • the invention further relates to a method of remotely invoking a function in a connection-oriented packet-switched (CO-PS) multi-protocol label switched (MPLS) communications network, particularly but not exclusively to a method which invokes an operation, administration, and/or maintenance (OAM) function by reassigning the purpose of the Time-To-Live (TTL) field of a MPLS packet.
  • CO-PS connection-oriented packet-switched
  • MPLS multi-protocol label switched
  • MPLS Transport Profile is a profile of MPLS which is being designed as a network layer technology in transport networks and further develops the Transport MPLS (MPLS-T or T-MPLS) technology.
  • MPLS-TP (and MPLS-T) is a connection-oriented packet switched (CO-PS) transport layer network technology based on MPLS modelled in International Telecommunications Union (ITU) standard document G.8110.
  • CO-PS connection-oriented packet switched
  • a protocol data unit (referred to herein as a traffic unit) which contains within its header fields a TTL field.
  • the TTL field in such early MPLS communications technologies is used generally to indicate the age of packets when they are received by a node in the network. This ensures that packets which for some reason or other have taken an unreasonable time to be forwarded to their destination are dropped. If the TTL field was not used to indicate how old a packet was the network would gradually become more and more congested with aging packets. Of particular importance here is the mitigation of traffic going endlessly round loops.
  • MPLS standards documents exist which set out the requirements for implementing OAM in a network based on MPLS technology.
  • the T-MPLS standards document G.8110.1 proposed that the T-MPLS OAM traffic unit contained a shim header with a label value 14, EXP field "000", the S bit set to 1 , and the TTL field set to 1 followed by the T-MPLS OAM payload defined in ITU Y.1711 entitled OAM mechanism for MPLS networks.
  • This use of a label is necessary as a standard MPLS traffic unit does not have a field to explicitly indicate that the MPLS or T-MPLS traffic unit (or equivalently packet) related to OAM. Instead, when a node received a traffic unit, the label field of each traffic unit had to be read and if the label value equalled 14 (a value reserved in these standards to serve as an OAM indicator) then the node could process that packet as an OAM packet.
  • CP control plane
  • MP management plane
  • MPLS is a data transport mechanism for packet-switched computer and telecommunications networks.
  • MPLS has been designed to provide a unified transport service for both circuit- based clients and packet-switching clients and can be used to carry many different types of traffic, for example, Internet Protocol (IP) packets as well as native Asynchronous Transfer Mode (ATM), Ethernet and Synchronous Optical NETwork (SONET) frames.
  • IP Internet Protocol
  • ATM Asynchronous Transfer Mode
  • SONET Synchronous Optical NETwork
  • OAM function for detecting/diagnosing defects in Label Switch Paths (LSP) and the increased requirement for the carriage of Ethernet clients with bit rates 1G/10G/+ which MPLS networks based on a Label Distribution Protocol (LDP) using PseudoWires (PWs) will find very difficult to support.
  • LDP Label Distribution Protocol
  • PWs PseudoWires
  • LDP and PHP
  • ECMP also violates transparency requirements of a client/server layer network relationship.
  • LDP/PHP/ECMP only account for some of the simpler architectural problems in MPLS.
  • Other problems include:
  • MPLS does not treat its clients consistently and so cannot form a proper layer network as it does not have consistent Characteristic Information (Cl).
  • Cl Characteristic Information
  • MPLS has a special relationship with IP (which can appear as a peer traffic unit on a MPLS interface (if CP/MP), or be a null encapsulated (if DP) client) and some fields of the MPLS traffic unit (especially the label field) do not have consistent functional semantics.
  • the MPLS traffic unit is not functionally complete, and in particular it has no OAM flag field.
  • LDP and PHP each cause a merging behaviour which, by violating the rules of a connection, prevents deterministic resource assignment/management and, as a consequence, makes other operational functions (such as fault detection/handling and performance monitoring) more complex and costly to implement.
  • this resources cannot be deterministically managed on a per customer/service instance. This means that the whole MPLS network has to be designed and operated to the demands of the most stringent customer service level agreement which is not cost effective for MPLS providers.
  • the MPLS traffic unit has an inadequate functional field structure and in particular the label field has too many semantics (i.e., a MPLS traffic unit does not have consistent Cl), which means that when connectivity errors occur a wrong decision might be made when interpreting the semantic of the label field.
  • MPLS does not have an Out Of Band (OOB) control/management plane solution as LDP prevents this.
  • OOB Out Of Band
  • both the DP traffic units and the OAM packets are subject to as near as possible identical processing in the DP. This means that both traffic units and OAM packets should have identical labelling fields and use the same number of headers. This is clearly not true when a further (OAM alert) labelled header is inserted after the normal traffic unit forwarding labelled header. This invention seeks to address this by incorporating a proper OAM flag field in a single MPLS traffic unit header.
  • One aspect of the invention seeks to provide a communications system comprising: a data plane network for multi-protocol label switching traffic; and a control plane for establishing connections in said data plane network, wherein said data plane multi-protocol label switching traffic comprises a plurality of traffic units, each traffic unit comprising at least one header and a payload area, each header comprising a label addressing field and at least one other field comprising one or more bits which is reserved to indicate if the payload carries client traffic or data for managing said client traffic.
  • control plane to establish connections in the data plane prevents traffic looping and renders the TTL field redundant in the MPLS traffic header.
  • This enables one or more of the bits in an MPLS header previously reserved for use as the TTL field to be reassigned to serve as an OAM indicate field whose value indicates whether the payload relates to client traffic or to data which manages said client traffic.
  • OAM traffic is able to be processed in the data plane network in a way more analogous to the client traffic it is serving as both the OAM and client traffic can share the same label addressing field value in their header which is used for forwarding purposes and have the same number of headers.
  • OAM MPLS traffic units require an additional header to the number of headers used by the client traffic being serviced by an MPLS LSP (Label Switched Path). This was due to the outer header label field values of the OAM traffic units being set to the same values as the client traffic units to ensure the OAM traffic follows the same path as the client traffic in the MPLS network, and the S bit of the outer header of an OAM traffic unit indicates the presence of an additional inner header, and this inner header would contain the reserved OAM alert value in the label field of the inner header.
  • the 0AM MPLS traffic units can be considered to more accurately monitor the MPLS LSP.
  • the control plane may be accessed using a logically adjunct network to said data plane network.
  • each data plane multi-protocol label switching traffic unit may not have a time- to-live field.
  • the TTL field may be retained in some embodiments of the invention.
  • the data for managing said client traffic implements one or more operations, administration, and/or management functions may be defined in a multi-protocol label switching technology communications standard as data relating to an OAM function.
  • the OAM traffic unit may have the same number of headers in its header stack as the client traffic with which it is associated.
  • One or more bits reserved for use as a time-to-live field in a header of a multi-protocol label switching traffic unit by another multi-protocol label switching communications protocol by be assigned in said communications system to said field.
  • Another aspect of the invention seeks to provide a method of invoking a function at a node in a multi-protocol label switching communications network operating in a connection oriented packet switched mode, the method comprising at the node: receiving a multi-protocol label switching traffic unit in which a field whose value comprising one or more bits of the header of the multi-protocol label switching traffic unit flags to the receiving node that one or more management functions are to be performed; processing the header of said multi-protocol label switched traffic unit to extract information from said one or more bits of said field; identifying the function to be invoked by the information extracted from the field; and causing said function to be invoked.
  • One or more bits of the Time-To-Live field of a header of a MPLS traffic unit may have been re-assigned to said field which flags to the receiving node to invoke said function.
  • One aspect of the invention seeks to provide a method of invoking a function at a node in a multi-protocol label switched (MPLS) communications network operating in a connection oriented packet switched (CO-PS) mode, the method comprising at the node: receiving a MPLS traffic unit to which one or more bits of the time-to-live (TTL) field of a header of a data packet have been re-assigned to invoke said function; processing the header of said MPLS traffic unit to extract information from said one or more bits of said TTL field; identifying the function to be invoked by the information extracted from the TTL field; and causing said function to be invoked.
  • MPLS multi-protocol label switched
  • CO-PS connection oriented packet switched
  • said one or more bits of said TTL field form a single word lexicon for invoking said function.
  • one or more bits of said TTL field form a flag field for invoking said function.
  • said function to be invoked comprises an operations, administration and/or maintenance (OAM) function.
  • OAM operations, administration and/or maintenance
  • said OAM function is defined by an MPLS OAM standard.
  • said MPLS communications network implements said connection oriented packet switched (CO-PS) mode by requiring specific traffic units having a MPLS communications network header contain a label field whose value is known in the MPLS network to indicate the type of management data the packet is conveying.
  • the label field value is "well-known" in that it is known in a network-wide sense.
  • said management data provides control plane functionality.
  • said management data provides management plane functionality.
  • control plane functionality is assigned a different label field value from the label field value assigned to management plane functionality.
  • this label field value is "well-known" in that it is known in a network-wide sense.
  • said label field value is unique in the MPLS network and comprises a value reserved as a globally unique value according to a MPLS standard between the value of 4 and 13 or 15.
  • a second aspect of the invention seeks to provide apparatus arranged to remotely invoke a function in a multi-protocol label switched communications (MPLS) network having a control plane enabling the network to operate in a CO-PS mode, apparatus comprising: a MPLS traffic unit generator arranged to generate a MPLS traffic unit having a multiprotocol label switched communications network header; a processor arranged to assign one or more bits of the time-to-live field of said header to indicate said function, a transmitter arranged to transmit said MPLS traffic unit to other apparatus in said
  • MPLS multi-protocol label switched communications
  • MPLS network whereby when other MPLS apparatus in said MPLS network receives said traffic unit and processes said header field values, said other apparatus causes said function to be invoked.
  • Another aspect of the invention seeks to provide a signal comprising a multi-protocol label switched (MPLS) communications traffic unit transmitted in a MPLS communications network, the traffic unit comprising a header in which one or more bits of the time-to-live field represent a function to be invoked by apparatus receiving said signal in said MPLS communications network.
  • MPLS multi-protocol label switched
  • Another aspect of the invention seeks to provide a multi-protocol label switched (MPLS) communications network comprising a plurality of multi-protocol label switched communications nodes, the network comprising: a control plane enabling said MPLS network to operate in a connection-oriented packet-switched mode; a transmitting node arranged to generate a MPLS traffic unit having a MPLS header and having a processor arranged to assign one or more predetermined bits of the time-to-live field of said header to indicate said function, and further comprising a transmitter arranged to transmit said packet to a node of said multi-protocol label switched network; a receiving node arranged to receive a MPLS traffic unit generated by said transmitting node, wherein when said receiving node receives said MPLS traffic unit and processes said header field values said function is invoked.
  • MPLS multi-protocol label switched
  • Another aspect of the invention seeks to provide a node in a communications system aspect of the invention, the node comprising: at least one interface to access said data plane network for multi-protocol label switching traffic; and at least one interface with said control plane.
  • Another aspect of the invention seeks to provide a signal comprising a multi-protocol label switching communications traffic unit transmitted in a multi-protocol label switching communications system aspect of the invention.
  • Another aspect of the invention seeks to provide apparatus arranged to generate a multi- protocol label switching protocol traffic unit for performing an in-band OAM function in a multi- protocol label switching communications network operating in a connection-oriented packet switched communications mode, the apparatus comprising: means for assigning to a header of said multi-protocol label switching traffic unit a value in an OAM field of said header, the OAM field comprising one or more bits, wherein the value conveyed in said OAM field flags to other nodes in said network that said traffic unit relates to an OAM function.
  • Another aspect of the invention seeks to provide a node in a multi-protocol label switching communications network operating in a connection oriented packet switched mode, the node comprising: means to receive a multi-protocol label switching traffic unit comprising at least one header and payload area, wherein the outermost header comprises a label field and another field comprising one or more bits whose value flags a receiving node that one or more management functions are to be performed for other traffic units having the same outermost label field value as the received traffic unit but which have a different value in said other field; and means to process the header of said multi-protocol label switched traffic unit to extract information from said one or more bits of said field to identify the function to be invoked by the information extracted from the field in order to cause said function to be invoked for said other traffic units.
  • one embodiment of the invention seeks to provide a solution to the lack of any OAM flag functionality being supported in a MPLS header by reassigning one bit of the 8-bit TTL field of the MPLS header to provide an OAM flag function.
  • Other embodiments may use more than one bit of the 8-bit TTL field.
  • One way of providing a MPLS network with an OOB CP and/or MP is to assign a network-wide label field header value to designate a MPLS traffic unit as carrying CP/MP protocols.
  • Figure 1 shows schematically a MPLS header known in the art
  • Figure 2 shows schematically an embodiment of a layered MPLS communications system having a logically OOB CP/MP network adjunct to the DP network according to the invention
  • Figure 3 shows schematically a MPLS header according to an embodiment of the invention.
  • MPLS is provided as an intermediate layer between the layer 2 and layer 3 headers of a typical packet.
  • IETF Internet Engineering Task Force
  • MPLS standards have already been defined by the Internet Engineering Task Force (IETF) standards body and these documents are considered to be incorporated herein by reference.
  • the ITEF Request for Comments document RFC 3032 (amongst others) describes MPLS Label Stack Encoding and is incorporated herein by reference.
  • Figure 1 of the accompanying drawings shows a 32-bit MPLS header as is known in the art.
  • the MPLS header comprises four fields: an 8-bit time to live (TTL) field, a 1-bit stack (S) function field, a 3-bit field (EXP) for experimental functions, and a 20-bit label field as are well known in the art.
  • the 20-bit label field provides 2 20 possible label values which, apart from sixteen reserved values (0 to 15), are of local link significance only in the MPLS network.
  • the sixteen reserved values are globally well-known label field values. Of the sixteen reserved label values available, label values 0 to 3 and 14 already have a defined use. Label values 4 to 13 and 15 are also reserved but do not have predefined usage according to the original MPLS standards, although one or more values may be reserved for other use without being detrimental to the implementation of some embodiments of the invention.
  • the MPLS communications network must be capable of functioning in an architecturally correct CO-PS mode.
  • CO-PS mode requires the OOB CP/MP protocols to operate on a hop-by-hop basis between pairs of MPLS network nodes so that at each MPLS network node the header of the MPLS traffic unit is processed ("popped") to enable access to the higher-layer CP/MP communications protocols at that node as appropriate.
  • the CO-PS layer MPLS network is able to invoke at each MPLS node a higher CP/MP communications protocol capable of imposing a Time-To-Live type functionality, e.g. the CP/MP protocols may run over IP in the logical OOB CP/MP network of the overall CO-PS network system.
  • providing the MPLS CO-PS layer network is operating in a mode which enables higher layer CP/MP protocols to be accessed at each MPLS node in the MPLS communications network which have their own TTL-equivalent functionality, the MPLS traffic units themselves do not require a TTL function to be provided.
  • OAM Operations, Administration and Maintenance
  • a predetermined number of one or more bits of the TTL field is/are reassigned to function as a flag for invoking OAM functionality at an MPLS mode.
  • the remaining bits can be used to invoke other types of functionality.
  • all MPLS traffic units are capable of re-using the TTL field.
  • DP data plane
  • MP management plane
  • CP control plane
  • the CO-PS mode functionality is imposed by the CP and/or MP and the TTL field is re-used only for some DP traffic but not for other DP traffic.
  • This may be of use if a hybrid MPLS network is provided in which the OOB CP and/or MP operates in a connection-oriented mode for some DP traffic but other types of DP traffic are transported by MPLS traffic units operating in a connectionless mode.
  • the MPLS network respects the requirements of a connection (the most important of which is that a connection can only have a single source) and has a CP and/or MP which enables the MPLS network to set-up connections without loops.
  • CO-CS connection-oriented circuit-switched
  • these are well-known behaviours for both CO-PS and connection-oriented circuit-switched (CO-CS) mode networks, and they have been used in many existing connections technologies (e.g. ATM, FR, SDH, PSTN) where a control and/or management plane is used to set-up/tear-down connections.
  • the CP and/or MP' provide the necessary routing/signalling information to ensure each connection does not loop and to ensure sufficient resource reservation.
  • a CP and/or MP capable of enforcing CO-PS connectivity is provided by the use of a special label field value in the header of a MPLS traffic unit (or equivalently, MPLS packet) to indicate the type of functionality the MPLS traffic unit relates to.
  • This special label field value must be known (with respect to its functional semantic) on a given link and should ideally be unique within a MPLS network, i.e., it should have a network-wide well-known functional significance.
  • the special label field value is selected from a value remaining available in the 0-15 reserved set of MPLS values.
  • the special label value assigned indicates that the MPLS traffic unit (i.e., the MPLS packet) is carrying control or management protocols as opposed to "normal" client traffic.
  • assigning a globally unique reserved label field value it is possible for one embodiment of the invention to support a logically out of band control/management plane in a MPLS network.
  • FIG. 2 shows schematically two nodes A and B in an embodiment of a layered MPLS communications system having a logically OOB CP/MP network adjunct to the DP network according to the invention.
  • client MPLS traffic units are sent out over the DP network to node B which use general label field values.
  • Nodes A and B are also able to access CP/MP communications protocol functionality in an adjunct CP/MP layer network.
  • the MPLS traffic units which relate to this logically different CP/MP network use a special value in their label field. This indicates to any receiving node that the CP/MP traffic units for a particular client traffic flow can be forwarded along a different logical network (and/or physical network path) to the client traffic to which they relate.
  • Figure 2 also shows schematically how MPLS traffic units forming the data plane (DP) traffic between two nodes A and B use the unreserved general labels (of which 2 20 -16 are available).
  • DP data plane
  • control plane is defined herein as functionality which is associated with the protocols relating to network topology discovery, route calculation and signalling.
  • the control plane may comprise any suitable communications protocols which implement the different functions.
  • the control plane is a sub-set of the connectivity configuration aspects of the management plane (or equivalent the connectivity configuration level of functionality) by which the apparatus (for example, the MPLS network nodes) are connected by a communications network support.
  • the connectivity configuration management functions which are related to the specific tasks of discovery/assignment/managing connectivity and/or signalling resources in the communications network are generally referred herein to as (belonging to) the control plane.
  • Other management functions i.e., ones not related to the above specific tasks
  • the protocols that implement the control plane (CP) and/or management plane (MP) functionality are carried by MPLS traffic units which have headers to which have been assigned one or more specially predetermined and ideally network-wide known values.
  • a special label value has a predetermined label value between 4 and 13 and 15.
  • all CP and/or MP traffic respectively is allocated a special network-wide label value reserved for the relevant function. This means that when a node receives a packet with the reserved label, it can be recognised as CP and/or MP traffic and is treated accordingly.
  • a special network-wide label value indicates that the MPLS traffic unit conveys CP protocol information and another special network-wide label value (for example, "Y”) indicates that the MPLS traffic unit conveys MP protocol information.
  • a set of reserved labels are assigned to different CP and MP protocols; for example, label value "X” for routing, label value "Y” for signalling, and label value "Z” to indicate any other MP function.
  • label value "X" for routing
  • label value "Y” for signalling
  • label value "Z” to indicate any other MP function.
  • a MPLS network node receiving a traffic unit i.e., a packet
  • a traffic unit i.e., a packet
  • the receiving MPLS network node needs to be able to resolve what type of function/protocol is being provided by a traffic unit which has a special network-wide value in its header label field.
  • IP Internet Protocol
  • SA Source Address
  • PID Protocol Identifier
  • D_Port Destination Port
  • S_Port Source Port
  • PWs PseudoWires
  • LDP Label Distribution Protocol
  • a further significant benefit of what has been described so far is that Service Level Agreements can be provided specific to a customer's needs, and there is no longer any need to design and/or operate the whole MPLS network to the service level agreement of the most demanding customer as was done in the prior art for the LDP type of MPLS in those embodiments where an OOB CP and/or MP was not provided.
  • the OAM of a CO-PS layer network is intrinsically associated with the trail termination function (and not the higher, architecturally, client/server adaptation functions). It is therefore important that the OAM itself and the OAM flag are associated with the traffic units of the connection irrespective of the client the connection is carrying (which may be no client 'at the present time' if the connection is a protection path for example, but nevertheless still needs to be monitored with OAM to ensure it is still functioning).
  • a MPLS traffic unit may either (i) comprise one or more special label value(s) having network-wide uniqueness and which indicate the MPLS traffic unit conveys control and/or management plane data or (ii) comprise normal forwarding labels which indicate the MPLS traffic unit is carrying client traffic, but in both cases one or more or all of the 8-bits of the TTL field of the MPLS header are no longer used to provide a TTL function.
  • a MPLS network is able to operate as a CO-PS mode layer network one or more bits of the TTL field are instead used to flag to a receiving network node that one or more management functions are to be performed.
  • management functions such as, for example, one or more operations, administration and management (or maintenance) (OAM) functions to be invoked.
  • OAM operations, administration and management
  • Such OAM functions are well known to those of ordinary skill in the art from, for example, the ITU MPLS OAM standard Y.171 1.
  • a MPLS traffic unit in which the TTL field in the header has been replaced with a 1-bit OAM flag field (the remaining 7 bits being reserved) according to one embodiment of the invention is shown schematically in Figure 3 of the accompanying drawings.
  • a more general treatment of the re-assigned 8-bit TTL field uses the entire 8-bit TTL field to provide a single 8-bit word. This provides the largest code space as it enables a maximum of 256 8-bit words to be provided in this single lexicon.
  • FIG. 1 For example, a smaller code space results from treating it as a set of 8 independent flags, i.e. there are 8 different lexicons here, each one having only 2 1-bit words (i.e. 0 or 1). Alternatively, one could use it as a single flag field (single lexicon) with only 2 8-bit words, i.e. 00000000 or 111111111 say, with all other 8-bit words being 'not allowed 1 .
  • the invention may be applied to Transport MPLS (T-MPLS) as well as to MPLS to provide an OAM flag for this communications protocol as well.
  • T-MPLS Transport MPLS
  • OAM flag for this communications protocol as well.
  • out-of-band refers to a different logical and/or physical communications channel (or equivalently link or connection) to the channel (or link or connection) used by client (data plane) traffic.
  • in-band refers to the logical and physical channel (or link or connection) used by client (data plane) traffic.
  • DP data plane
  • the OOB CP/MP creates an adjunct layer network within the same overall communications network system for controlling and/or managing the associated DP.
  • the CP/MP protocols operate outside and are independent of the client traffic DP (at least logically if not physically as well).
  • a particular reserved label value is used to indicate a traffic unit relates to a different layer network which is not part of the data plane network but does control and/or manage the data plane network.
  • This logically different network thus provides an OOB CP/MP network which is not part of the DP traffic layer network but does control/manage it.
  • the proposal for re-use of the TTL field is in the client DP but marks the OAM traffic units in the client DP as OAM by using a field whose value serves as an OAM indicator.
  • Conventional MPLS communications traffic units do not have an OAM indicator field but are identified as relating to OAM by assigning a reserved value in the "label field", i.e., the field otherwise used for forwarding the MPLS traffic unit.
  • label field i.e., the field otherwise used for forwarding the MPLS traffic unit.
  • the OAM indicator field (previously the TTL field) is always part of the data plane (client) traffic network but is used to indicate when a traffic unit carries OAM payload as opposed to client traffic payload.
  • a multi-protocol label switched communications (MPLS) network comprising a plurality of multi-protocol label switched communications nodes further comprises a control plane enabling said MPLS network to operate in a connection-oriented packet-switched mode; a transmitting node arranged to generate a MPLS traffic unit having a MPLS header and having a processor arranged to assign one or more predetermined bits of the Time-To-Live (TTL) field of said header to indicate said function, and further comprising a transmitter arranged to transmit said packet to a node of said multi-protocol label switched network; a receiving node arranged to receive a MPLS traffic unit generated by said transmitting node, wherein when said receiving node receives said MPLS traffic unit and processes said header field values said function is invoked.
  • TTL Time-To-Live

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  • Data Exchanges In Wide-Area Networks (AREA)

Abstract

L'invention porte sur un réseau de communications à commutation multiprotocole par étiquette (MPLS) comprenant une pluralité de nœuds de communications à commutation multiprotocole par étiquette, lequel réseau comprend en outre un plan de commande permettant audit réseau MPLS de fonctionner dans un mode à commutation de paquets orientée connexion ; un nœud d'émission agencé pour générer une unité de trafic MPLS ayant un en-tête MPLS et ayant un processeur agencé pour attribuer un ou plusieurs bits prédéterminés du champ durée de vie (TTL) dudit en-tête pour indiquer ladite fonction, et comprenant en outre un émetteur agencé pour transmettre ledit paquet à un nœud dudit réseau à commutation multiprotocole par étiquette ; un nœud de réception agencé pour recevoir une unité de trafic MPLS générée par ledit nœud d'émission, dans lequel, lorsque ledit nœud de réception reçoit ladite unité de trafic MPLS et traite lesdites valeurs de champ d'en-tête, ladite fonction est invoquée. La réutilisation du champ TTL permet à une fonctionnalité OAM d'être fournie dans un réseau MPLS fonctionnant entièrement en mode CO-PS.
PCT/GB2009/000069 2008-01-09 2009-01-09 Système de communications mpls et aspects apparentés WO2009087400A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
EP08250086A EP2079188A1 (fr) 2008-01-09 2008-01-09 Procédé hors bande pour la gestion d'un réseau de communications MPLS
EP08250094.3 2008-01-09
EP08250094A EP2079189A1 (fr) 2008-01-09 2008-01-09 Schéma d'invocation de fonction MPLS et aspects associé
EP08250086.9 2008-01-09

Publications (1)

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WO2009087400A1 true WO2009087400A1 (fr) 2009-07-16

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PCT/GB2009/000047 WO2009087384A1 (fr) 2008-01-09 2009-01-09 Procédé de gestion hors bande d'un réseau de communications mpls et aspects apparentés

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003081850A1 (fr) * 2002-03-27 2003-10-02 Siemens Aktiengesellschaft Procede de fonctionnement et de surveillance de reseaux mpls
WO2003094442A1 (fr) * 2002-04-29 2003-11-13 Siemens Aktiengesellschaft Procede pour surveiller la qualite de transmission de liaisons dans des reseaux mpls

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003081850A1 (fr) * 2002-03-27 2003-10-02 Siemens Aktiengesellschaft Procede de fonctionnement et de surveillance de reseaux mpls
WO2003094442A1 (fr) * 2002-04-29 2003-11-13 Siemens Aktiengesellschaft Procede pour surveiller la qualite de transmission de liaisons dans des reseaux mpls

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
DAVID ALLAN NORTEL NETWORKS: "A Framework for MPLS Data Plane OAM; draft-allan-mpls-oam-frmwk-05.txt", IETF STANDARD-WORKING-DRAFT, INTERNET ENGINEERING TASK FORCE, IETF, CH, no. 5, 1 October 2003 (2003-10-01), XP015010020, ISSN: 0000-0004 *
ITU-T: "Recommendation Y.1714", ITU-T SERIES Y RECOMMENDATIONS, 1 January 2007 (2007-01-01), XP002529702 *

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