WO2019128621A1 - 一种组播虚拟专用网络的承载方法和设备 - Google Patents

一种组播虚拟专用网络的承载方法和设备 Download PDF

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Publication number
WO2019128621A1
WO2019128621A1 PCT/CN2018/118564 CN2018118564W WO2019128621A1 WO 2019128621 A1 WO2019128621 A1 WO 2019128621A1 CN 2018118564 W CN2018118564 W CN 2018118564W WO 2019128621 A1 WO2019128621 A1 WO 2019128621A1
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packet
forwarding
multicast
global vpn
vrf
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PCT/CN2018/118564
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English (en)
French (fr)
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彭少富
金飞蔡
徐本崇
蔡宁
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中兴通讯股份有限公司
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Priority to EP18897800.1A priority Critical patent/EP3734906B1/en
Priority to US16/956,639 priority patent/US11196580B2/en
Publication of WO2019128621A1 publication Critical patent/WO2019128621A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/02—Details
    • H04L12/16—Arrangements for providing special services to substations
    • H04L12/18—Arrangements for providing special services to substations for broadcast or conference, e.g. multicast
    • H04L12/1836—Arrangements for providing special services to substations for broadcast or conference, e.g. multicast with heterogeneous network architecture
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/02—Details
    • H04L12/16—Arrangements for providing special services to substations
    • H04L12/18—Arrangements for providing special services to substations for broadcast or conference, e.g. multicast
    • H04L12/1863—Arrangements for providing special services to substations for broadcast or conference, e.g. multicast comprising mechanisms for improved reliability, e.g. status reports
    • H04L12/1877—Measures taken prior to transmission
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/02—Details
    • H04L12/16—Arrangements for providing special services to substations
    • H04L12/18—Arrangements for providing special services to substations for broadcast or conference, e.g. multicast
    • H04L12/185—Arrangements for providing special services to substations for broadcast or conference, e.g. multicast with management of multicast group membership
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • H04L12/46—Interconnection of networks
    • H04L12/4604—LAN interconnection over a backbone network, e.g. Internet, Frame Relay
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • H04L12/46—Interconnection of networks
    • H04L12/4633—Interconnection of networks using encapsulation techniques, e.g. tunneling
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • H04L12/46—Interconnection of networks
    • H04L12/4641—Virtual LANs, VLANs, e.g. virtual private networks [VPN]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • H04L12/46—Interconnection of networks
    • H04L12/4641—Virtual LANs, VLANs, e.g. virtual private networks [VPN]
    • H04L12/4675—Dynamic sharing of VLAN information amongst network nodes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/02—Topology update or discovery
    • H04L45/04—Interdomain routing, e.g. hierarchical routing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/16—Multipoint routing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/50—Routing or path finding of packets in data switching networks using label swapping, e.g. multi-protocol label switch [MPLS]

Definitions

  • the present invention relates to the field of data communications, and in particular, to a bearer method and device for a multicast virtual private network.
  • BIER Bit Indexed Explicit Replication
  • BitString a bit string (BitString)
  • BitString a bit string (BitString)
  • each bit of BitString represents the BFR-id of the corresponding BFER (Bit-Forwarding Egress Router)
  • the Identifier bit forwards the router index).
  • the standard draft draft-ietf-bier-mvpn-06 describes a BIER-type carrier tunnel (P-tunnel) as a public network bearer method for a multicast VPN (Virtual Private Network).
  • This method uses upstream allocation of MPLS labels. (upstream-assigned MPLS label), because the BIER belongs to the P-node replication technology, that is, the BIER-encapsulated multicast routing (VRF) label for all egress PEs (Provider Edge, network side edge devices) ) must be the same.
  • VRF BIER-encapsulated multicast routing
  • the MPLS (Multi-Protocol Label Switching) label is not widely used.
  • the identifier of the specific context label space may be a tunnel identifier (tunnel id), an IP address, an MPLS label, a VLAN (Virtual Local Area Network) identifier, or a draft-ietf-bier-mvpn-06
  • tunnel identifier tunnel identifier
  • IP address IP address
  • MPLS label Virtual Local Area Network
  • VLAN Virtual Local Area Network
  • VLAN Virtual Local Area Network
  • Any information such as the BFIR identifier depends on different application scenarios. So many identification information seems to be flexible. In fact, it is not feasible for the forwarding chip with tight space resources.
  • the related technology also lacks the constraint and unified specification for the context label space identifier. Under this premise, many devices choose not to support the upstream allocation of MPLS labels, and thus the BIER-based multicast VPN method cannot be implemented.
  • the embodiment of the invention provides a bearer method for a multicast virtual private network VPN, including:
  • the bit forwarding ingress router BFIR that accesses the multicast virtual private network routing and forwarding VRF allocates a global VPN identifier to the multicast VRF, and carries the global VPN identifier when the route is forwarded to the multicast forwarding egress router BFER.
  • the BFIR After receiving the packet of the multicast VRF, the BFIR explicitly copies and forwards the BIER header for the packet encapsulation bit index, where the forwarded packet carries the global VPN identifier.
  • the embodiment of the present invention further provides a bit forwarding ingress router, comprising: an identifier allocation module, configured to allocate a global VPN identifier to a multicast virtual private network routing and forwarding VRF accessed by the local forwarding ingress router BFIR; and a route advertisement module is set to Dedicating a route to the bit forwarding egress router BFER that accesses the multicast VRF, where the route carries the global VPN identifier; and the packet forwarding module is configured to: after receiving the packet of the multicast VRF, The packet encapsulation bit index explicitly copies the BIER header and forwards the packet, where the forwarded packet carries the global VPN identifier.
  • the embodiment of the present invention further provides a bearer method for a multicast virtual private network VPN, including: accessing a multicast virtual private network route forwarding VRF bit forwarding egress router BFER to allocate a global VPN identifier to the multicast VRF, and recording The forwarding information of the packet with the global VPN identifier; after receiving the packet with the global VPN identifier, the BFER removes the BIER header of the packet, searches for the forwarding information, and forwards the packet.
  • the embodiment of the present invention further provides a bit forwarding egress router, including: an identifier allocation module, configured to allocate a global VPN identifier to a multicast virtual private network routing and forwarding VRF accessed by the local forwarding ingress router BFIR; and the information recording module is set to Recording the forwarding information of the packet with the global VPN identifier; the packet forwarding module is configured to remove the BIER header of the packet after receiving the packet with the global VPN identifier, and search for the forwarding information. And forward the message.
  • an identifier allocation module configured to allocate a global VPN identifier to a multicast virtual private network routing and forwarding VRF accessed by the local forwarding ingress router BFIR
  • the information recording module is set to Recording the forwarding information of the packet with the global VPN identifier
  • the packet forwarding module is configured to remove the BIER header of the packet after receiving the packet with the global VPN identifier, and search for the forwarding information. And forward the message.
  • An embodiment of the present invention further provides a bit forwarding ingress router, including a memory, a processor, and a computer program stored on the memory and operable on the processor, where the processor implements the computer program Treatment of the method of the embodiment.
  • the embodiment of the invention further provides a computer readable storage medium, on which a computer program is stored, and when the computer program is executed by the processor, the processing of the method of the embodiment is implemented.
  • the solution in the foregoing embodiment implements packet forwarding by using a global VPN identifier.
  • the forwarding mechanism is simpler and easier to implement and deploy.
  • FIG. 1 is a network topology diagram of a basic multicast VPN scenario according to an embodiment of the present invention
  • FIG. 2 is a flowchart of a multicast VPN bearer method on the BFIR side according to an embodiment of the present invention
  • FIG. 3 is a block diagram of a forwarding ingress router according to an embodiment of the present invention.
  • FIG. 4 is a flowchart of a multicast VPN bearer method on the BFER side according to Embodiment 2 of the present invention.
  • FIG. 5 is a block diagram of a two-bit forwarding egress router according to an embodiment of the present invention.
  • FIG. 6 is a network topology diagram of a scenario of a cross-domain option A (option A) of a multicast VPN according to an embodiment of the present invention
  • FIG. 7 is a network topology diagram of a scenario of a cross-domain option B (option B) of a multicast VPN according to an embodiment of the present invention
  • FIG. 8 is a network topology diagram of a scenario of a multicast VPN cross-domain option C (option C) according to Embodiment 7 of the present invention.
  • This embodiment provides a method for carrying a multicast VPN.
  • the method for carrying a multicast VPN involves forwarding the multicast VPN packets and processing related to packet forwarding, such as identity allocation and route advertisement.
  • FIG. 1 is a network topology diagram of a basic multicast VPN scenario.
  • BFIR is connected to the VRF_A multicast source S, and BFER1 to BFER3 are respectively connected to the multicast receiving ends rcv1 to rcv3 of the VRF_A.
  • the figure also shows the BFIR and BFER.
  • BFR Bit-Forwarding Router
  • VRF_A represents a multicast VRF instance named A.
  • BFIR and S are not necessarily directly connected.
  • BFIR only needs to know that the left inbound interface is connected to the multicast source. The same is true for the connection between the BFER and the multicast receiving end. The two are not necessarily directly connected.
  • the BFER only needs to know that the right outgoing interface is connected to the multicast receiving end.
  • Both BFIR and BFER belong to the PE node that accesses the multicast VRF.
  • FIG. 2 is a flowchart of a multicast VPN bearer method on the BFIR side of the embodiment, including:
  • Step 110 The BFIR that accesses the multicast VRF allocates a global VPN identifier to the multicast VRF, and carries the global VPN identifier when the route is forwarded to the BEF that accesses the multicast VRF.
  • the same global VPN id is assigned to the same multicast VRF on each border PE for the multicast VPN service. That is, on the PE accessing a multicast VRF, the global VPN identifier is used to uniquely identify the multicast VRF.
  • the global VPN ID of the multicast VPN can be uniformly distributed by the controller and delivered to each border PE, or statically configured by the administrator on each border PE, or otherwise.
  • the BGP Border Gateway Protocol
  • I-PMSI Inclusive P-Multicast Service Interface
  • AD auto-discovery
  • the S-PMSI Selective P-Multicast Service Interface
  • the global VPN identifier of the multicast VRF may be carried in the MPLS label field of the advertised route.
  • the tunnel attribute of the BGP I-PMSI A-D or the S-PMSI A-D route of the PMS (P-Multicast Service Interface) tunnel advertised in this embodiment includes the following fields:
  • Tunnel Type Use the extended value to indicate the "BIER with global VPN” type.
  • Tunnel Identifier Includes the following two information: BIER sub-domain id, BFIR-Prefix.
  • MPLS Label This field is generally set to a certain label value in RFC6514. In this embodiment, it is set to "global VPN id".
  • Flags Contains two flag bits: 1) "Leaf Info Required” flag, which is defined as RFC6514; 2) "Leaf Info Required per Flow (LIR-pF)” flag, which is defined as draft-ietf- Bess-mvpn-expl-track.
  • the present embodiment extends the tunnel type based on the PMSI Tunnel Attribute defined by rfc6514, and adds a new tunnel type, which is referred to as an "extended protocol type" in this application.
  • the extended tunnel type is used to indicate that the tunnel is based on a BIER that uses a global VPN identity, ie, a BIER that is improved in this embodiment.
  • the extended tunnel type is referred to as the "BIER with global VPN” type in this embodiment, but the present application is not limited thereto, and other names may be used in the specific names.
  • the "BIER with global VPN” type can be represented by the extended value of the Tunnel Type field.
  • Step 120 After receiving the packet of the multicast VRF, the BFIR encapsulates the BIER header and forwards the packet, and the forwarded packet carries the global VPN identifier.
  • the BFIR creates an instance of the multicast VRF.
  • the extended tunnel type indication tunnel is used based on the BIER using the global VPN identifier; the BFIR is received.
  • the route matching the packet is found in the multicast VRF routing table, and the tunnel type of the route is determined to be the extended tunnel type.
  • the global VPN identifier pushes the packet; after that, the BIER header is encapsulated and forwarded.
  • the tunnel type in the route is also set to an extended tunnel type, and the extended tunnel type is used to indicate that the tunnel is based on the use.
  • BIER for global VPN ID.
  • the BFIR does not create an instance for the multicast VRF.
  • the global VPN is established in the forwarding table. An entry that is identified as a key, in which the forwarding information of the packet carrying the global VPN identifier is recorded; after the BFIR receives the packet of the multicast VRF, the packet is removed.
  • the second layer header after determining that the layer 2 header includes the global VPN identifier according to the extended protocol type in the layer header, the forwarding information is found from the forwarding table; and then the packet is encapsulated BIER headers are forwarded.
  • the BFIR may also carry the global VPN identifier, and set the tunnel type in the route to the extended tunnel type. .
  • the protocol type of the Layer 2 encapsulation is extended, and the upstream node (such as the BFER of another domain) is used in the Layer 2 header when forwarding the packet of the multicast VRF to the BFIR.
  • the extended protocol type is used to indicate that the Layer 2 header includes the global VPN identifier.
  • the extended protocol type can be represented by a value of the protocol type field extension.
  • the extended protocol type can be called “Multicast global VPN”, but this There is no restriction on the application for its name.
  • the BFIR may determine the global VPN identifier after the Layer 2 header is determined according to the extended protocol type in the Layer 2 header of the packet, and the global VPN identifier does not need to be pushed in again.
  • the Layer 2 encapsulation is a data link layer encapsulation of the packet after the BIER header is removed.
  • the protocol type in the Layer 2 header is extended.
  • the global VPN identifier for encapsulating and parsing the multicast VRF packet can be supported.
  • the node resolves the Layer 2 header of the packet, it can know that the Layer 2 header is followed by a global VPN id according to the protocol type "Multicast global VPN" in the Layer 2 header.
  • the packet type in the BIER header is extended, and when the BFIR encapsulates the BIER header, the packet type in the BIER header is set to be extended.
  • the packet type is used to indicate the global VPN identifier carrying the multicast VRF in the packet.
  • the type of the packet in the BIER header can be extended to encapsulate and parse the global VPN identifier of the multicast VRF packet in the multicast VRF packet.
  • a new value is added to the Proto field to indicate the extended packet type, and the extended packet type. It may be referred to as "Multicast global VPN", but the application is not limited thereto.
  • This embodiment further provides a bit forwarding ingress router, as shown in FIG. 3, including:
  • the identifier allocation module 10 is configured to allocate a global VPN identifier to the multicast virtual private network route forwarding VRF accessed by the local forwarding ingress router BFIR;
  • the route advertisement module 20 is configured to advertise a route to the bit forwarding egress router BFER that accesses the multicast VRF, where the route carries the global VPN identifier;
  • the packet forwarding module 30 is configured to: after receiving the packet of the multicast VRF, explicitly copy and forward the BIER header for the packet encapsulation bit index, where the forwarded packet carries the global VPN Logo.
  • the bit forwarding ingress router further includes: an instance creation module, configured to create an instance for the multicast VRF, in the route of the multicast VRF routing table corresponding to the instance, using the extended tunnel type to indicate that the tunnel is based on using the global VPN identifier BIER;
  • the packet forwarding module is further configured to: find a route matching the packet from the multicast VRF routing table, and determine that the tunnel type of the route is When the extended tunnel type is described, the global VPN identifier is pushed into the packet; afterwards, the BIER header is encapsulated and forwarded for the packet.
  • the tunnel type in the route is also set to the extended tunnel type.
  • the global VPN identifier is carried in the multi-protocol label switching MPLS label field of the advertised route.
  • the bit forwarding ingress router includes an identifier allocation module, a route advertisement module, and a message forwarding module.
  • the functions of the identifier allocation module and the route advertisement module may be the same as the embodiment.
  • the bit forwarding ingress router further includes: a forwarding table maintenance module, configured to establish, in the forwarding table, an entry that uses the global VPN identifier as a key value, where the packet carrying the global VPN identifier is recorded in the entry After the packet forwarding module receives the packet of the multicast VRF, the packet forwarding module removes the Layer 2 header of the packet, and determines the Layer 2 header according to the extended protocol type in the Layer 2 header.
  • the forwarding information is found from the forwarding table; afterwards, the BIER header is encapsulated and forwarded.
  • the packet forwarding module When the packet forwarding module encapsulates the BIER header, the packet type in the BIER header is set to an extended packet type, and the extended packet type is used to indicate that the packet carries the group. Broadcast the global VPN ID of the VRF.
  • the network topology of this embodiment can be seen in FIG.
  • the first embodiment is to describe the bearer method of the multicast VPN from the BFIR side.
  • the bearer method of the multicast VPN is described from the BFER side.
  • Step 210 A BFER accessing a multicast VRF allocates a global VPN identifier to the multicast VRF, and records the global VPN identifier.
  • the forwarding information of the packet is received.
  • Step 220 After receiving the packet with the global VPN identifier, the BFER removes the BIER header of the packet, searches for the forwarding information, and forwards the packet.
  • the packet with the global VPN identifier is the packet of the multicast VRF, because the global VPN identifier is a unique identifier of the multicast VPN.
  • the BFER creates an instance of the multicast VRF, and the global VPN id is used to distinguish the multicast VRF routing table corresponding to different multicast VRF instances.
  • the BFER does not create an instance for the multicast VRF, and after the BFER allocates a global VPN identifier to the multicast VRF, the global VPN identifier is set as a key in the forwarding table. An entry in which the forwarding information of the packet with the global VPN identifier is recorded; and the BFER receives the packet with the global VPN identifier, and removes the BIER header of the packet. And determining, when the packet type in the BIER header is an extended packet type, searching for the forwarding information and forwarding the packet according to the global VPN identifier after the BIER header. The extended packet type is used to indicate the global VPN identifier carrying the multicast VRF in the packet.
  • the BFER performs packet forwarding, including: when the BFER performs Layer 2 encapsulation on the packet, setting a protocol type in the Layer 2 header to an extended protocol type, where the extension The protocol type is used to indicate that there is a global VPN identifier after the Layer 2 header.
  • This embodiment further provides a bit forwarding egress router, as shown in FIG. 5, including:
  • the identifier allocation module 50 is configured to allocate a global VPN identifier to the multicast virtual private network route forwarding VRF accessed by the local forwarding ingress router BFIR;
  • the information recording module 60 is configured to record forwarding information of the packet having the global VPN identifier
  • the packet forwarding module 70 is configured to remove the BIER header of the packet after receiving the packet with the global VPN identifier, and search for the forwarding information and forward the packet.
  • the information recording module records the forwarding information of the packet with the global VPN identifier, and includes: creating an instance of the multicast VRF, where the record has the global in the routing of the multicast VRF routing table corresponding to the instance Forwarding information of the packets marked by the VPN;
  • the packet forwarding module searches for the forwarding information and performs packet forwarding, including: determining that the packet type in the BIER header is an extended packet type, and removing the global VPN identifier after the BIER header. The remaining payloads are forwarded in the multicast VRF routing table, and the extended packet type is used to indicate the global VPN identifier carrying the multicast VRF in the packet.
  • the information recording module records the forwarding information of the packet with the global VPN identifier, and includes: establishing, in the forwarding table, an entry that uses the global VPN identifier as a key value, where the record is recorded in the entry Forwarding information of the packets of the global VPN identifier;
  • the packet forwarding module searches for the forwarding information and forwards the packet, and includes: when determining that the packet type in the BIER header is an extended packet type, according to the global VPN identifier after the BIER header
  • the forwarding table searches for the forwarding information and forwards the packet, and the extended packet type is used to indicate that the packet carries the global VPN identifier of the multicast VRF.
  • the packet forwarding module performs packet forwarding, including: when the packet is encapsulated in Layer 2, the protocol type in the Layer 2 header is set to an extended protocol type, and the extension is performed.
  • the protocol type is used to indicate that there is a global VPN identifier after the Layer 2 header.
  • the router can support the basic functions of the VRF (such as a VRF routing table instance or a forwarding table). Text forwarding. Therefore, the forwarding mechanism is simpler and easier to implement and deploy. Can be used to replace the way upstream MPLS labels are assigned.
  • This embodiment describes the overall flow of the multicast VPN bearer method based on the network topology diagram of the basic multicast VPN scenario.
  • the global VPN id is used by default to distinguish the multicast VRF routing table corresponding to different multicast VRF instances. It is applicable to the nodes that can create multicast VRF instances locally. For example, the ingress PE and egress PE nodes in the basic multicast VPN scenario. ). In general, you only need to assign a globally unique global VPN id to a multicast VRF. However, in order to support more application scenarios, multiple globally unique global VPN ids may be assigned to a multicast VRF. For example, in one example, according to a policy, different I-PMSIs (P-Multicasts) under the multicast VRF are used. Service Interface (Operator Multicast Service Interface) or S-PMSI AD route can use different global VPN ids.
  • P-Multicasts Service Interface
  • S-PMSI AD route can use different global VPN ids.
  • a new function can be introduced for the global VPN id, which is applicable to the nodes that do not create the multicast VRF instance, such as the ASBR node in the option B cross-domain scenario of the multicast VPN, directly in the forwarding table.
  • the global VPN id is used as the key to establish the entry, and the corresponding forwarding information is given in the entry to guide the packet carrying the global VPN id to the next hop.
  • the forwarding table may also be called "global”. VPN id forwarding table.”
  • using the global VPN id to distinguish the entire multicast VPN routing table is the default. You do not need to explicitly configure it. To create an entry with the global VPN id as the key, you need to explicitly configure the global VPN id on the node. The ability of a key to establish an entry (even if it is capable), or "global VPN id forwarding capability.”
  • the BFIR node accessing the VRF multicast source advertises the BGP I-PMSI AD or S-PMSI AD route to the BFER node that accesses the VRF multicast receiver, and the PTA (PMSI Tunnel Attribute, PMSI tunnel attribute) ) contains the information of the global VPN id of the multicast VRF, and sets the tunnel type to "BIER with global VPN" in the PTA, that is, "BIER with global VPN".
  • the tunnel type is different from draft-ietf-bier-mvpn- The type "BIER" defined in 06.
  • Other processing by the BFIR node to advertise the S-PMSI A-D or I-PMSI A-D route may be performed in accordance with the procedure defined in RFC 6513 so that the corresponding set of BFER nodes can be determined for the particular VRF multicast stream on the BFIR node.
  • the BFIR node searches for the S-PMSI AD or I-PMSI AD route to match the packet to be transmitted. If the PTA of the matching route indicates that the tunnel type is BIER with global VPN, the global VPN of the route is used.
  • the id first pushes the (push or insert) packet, such as adding the global VPN id before the original packet, and then encapsulating the BIER header and forwarding it.
  • the packet type encapsulated in the BIER header is set to the extended packet type, that is, "Multicast global VPN".
  • the packet type encapsulated in the BIER header is Multicast global VPN.
  • the BIER header in the text is followed by the global VPN id. After the BFER node removes the BIER header and the global VPN id, the BFER node continues to forward the remaining payloads in the multicast VRF routing table corresponding to the global VPN id.
  • the BFER node receives the BIER-encapsulated packet, removes the BIER header from the packet, and follows the global VPN after the BIER header.
  • the id is searched for the global VPN id forwarding table to obtain the corresponding forwarding information, and the packet is forwarded to the corresponding next hop.
  • This embodiment does not require the forwarding chip to establish a wide variety of context table spaces, but only needs to establish a VRF routing table instance, and establishing a VRF routing table instance is a basic function of the router supporting VRF. Therefore, the forwarding mechanism is simpler and easier to implement and deploy. It can be used to replace the way upstream MPLS labels are distributed and to improve existing standards.
  • FIG. 1 is a network topology diagram of a basic multicast VPN scenario in the embodiment.
  • the BFIR is connected to the VRF_A multicast source S, and the BFER1 to BFER3 are respectively connected to the multicast receiving ends rcv1 to rcv3 of the VRF_A.
  • VRF_A represents a VRF instance named A.
  • step 301 BFIR and BFER1 to BFER3 allocate a globally unique global VPN identifier (denoted as global VPN id 100) to VRF_A, and create an instance of VRF_A, including establishing a multicast VRF routing table of VRF_A.
  • global VPN id 100 globally unique global VPN identifier
  • the BFIR node advertises the BGP I-PMSI A-D or S-PMSI A-D route to each BFER node, and sets the tunnel type to "BIER with global VPN" in the PTA, and includes the global VPN id 100.
  • the other processing of the advertisement route may be performed according to the procedure defined in RFC6513, so that the BFIR node can determine the corresponding multicast receiver set for the specific multicast stream of the VRF_A as ⁇ BFER1, BFER2, BFER3 ⁇ , and the S node also determines that the BFIR is corresponding.
  • Step 303 The BFIR receives the specific multicast stream of the S, and searches for the S-PMSI AD or the I-PMSI AD route in the multicast VRF routing table corresponding to the locally maintained VRF_A instance to match the packet to be transmitted.
  • the PTA of the matched route indicates that the tunnel type is "BIER with global VPN”
  • the global VPN id of the route is first pushed into the packet, and then the BIER header is encapsulated and then forwarded.
  • the message type field encapsulated in the BIER header will be set to "Multicast global VPN", and the BitString in the BIER header will contain BFER1 to BFER3.
  • Step 304 The message is sent to the multicast service layer by locally removing the BIER header on the BFER1 to BFER3 according to the BIER forwarding process.
  • BFER1 knows the value of the packet type field encapsulated by the BIER header, "Multicast global VPN", and knows that the BIER header in the message is the global VPN id, so the BIER header and the global VPN id 100 are removed after the packet is removed. Then, the remaining payloads are forwarded in the multicast VRF routing table corresponding to the global VPN id 100, and the packets are sent to the rcv1 node.
  • BFER2 is similar to the processing of the BFER3 node.
  • FIG. 6 is a network topology diagram of the scenario of the multicast VPN cross-domain option A (option A) in this embodiment.
  • the scenario is actually spliced by two basic multicast VPN topologies.
  • the multicast source S is shown in the figure.
  • PE1 in the AS1 network corresponds to BFIR
  • ASBR1 corresponds to BFER
  • ASBR2 in AS2 network corresponds to BFIR
  • ASBR2 corresponds to BFER.
  • Step 401 PE1, PE2, ASBR1, and ASBR2 allocate a global VPN identifier (denoted as a global VPN id 100) to the VRF_A, and create an instance of the VRF_A, including establishing a multicast VRF routing table of the VRF_A.
  • a global VPN identifier denoted as a global VPN id 100
  • the PE1 advertises the BGP I-PMSI A-D or the S-PMSI A-D route to the ASBR1, and sets the tunnel type to "BIER with global VPN" and includes the global VPN id 100.
  • the other processing may be performed according to the process defined in RFC6513, so that the corresponding multicast receiver set for the specific multicast stream of the VRF_A can be determined as the ⁇ ASBR1 ⁇ on the PE1 node, and the S node also determines that the PE1 is the receiving end of the corresponding multicast stream. one.
  • step 403 the ASBR1 node continues to advertise the BGP I-PMSI A-D or S-PMSI A-D route to the ASBR2 node, and sets the tunnel type to "No tunnel information present" in the PTA (see RFC6514). Other processing may be performed according to the procedure defined in RFC6513, so that the ASBR1 node can determine the corresponding multicast receiver set as ⁇ ASBR2 ⁇ for the specific multicast stream of VRF_A.
  • the PIM protocol can also be enabled between ASBR1 and ASBR2.
  • the ASBR1 node can determine the corresponding multicast receiver set as ⁇ ASBR2 ⁇ for the specific multicast stream of VRF_A. This method is the existing standard content and will not be described again.
  • step 404 the ASBR2 node continues to advertise the BGP I-PMSI A-D or S-PMSI A-D route to the PE2 node, and sets the tunnel type to "BIER with global VPN" and includes the global VPN id 100.
  • Other processing may be performed in accordance with the procedure defined in RFC 6513, so that the ASBR2 node can determine the corresponding multicast receiver set as ⁇ PE2 ⁇ for the specific multicast stream of VRF_A.
  • ASBR2 can independently select the tunnel type, and does not have to be the same as the tunnel type of other domains.
  • ASBR2 has BIER forwarding capability, so the BIER forwarding mechanism is selected.
  • Step 405 PE1 receives the specific multicast stream of the S, and searches for the S-PMSI AD or I-PMSI AD route in the multicast VRF routing table corresponding to the locally maintained VRF_A instance to match the packet to be transmitted, and the matched route. If the PTA indicates that the tunnel type is "BIER with global VPN", the global VPN id of the route is first pushed into the packet, and then the BIER header is encapsulated and then forwarded. The message type field encapsulated in the BIER header will be set to "Multicast global VPN", and the BitString in the BIER header will contain the corresponding bit of ASBR1.
  • Step 406 The packet is sent to the multicast service layer by sending the BIER header locally on the ASBR1 according to the conventional BIER forwarding process.
  • the ASBR1 takes the value of the encapsulated packet type field in the BIER header as "Multicast global VPN". Knowing the BIER header in the message is the global VPN id information.
  • the ASBR1 node removes the BIER header and the global VPN id 100, the ASBR1 node continues to forward the remaining payloads in the multicast VRF routing table corresponding to the global VPN id 100, and the packets are sent to the ASBR2 node.
  • the ASBR2 receives the specific multicast stream of the ASBR1, and searches for the S-PMSI AD or I-PMSI AD route in the multicast VRF routing table corresponding to the locally maintained VRF_A instance to match the packet to be transmitted, and the matched route. If the PTA indicates "BIER with global VPN", the global VPN id of the route is first pushed into the packet, and then the BIER header is encapsulated and then forwarded. The packet type field encapsulated in the BIER header will be set to "Multicast global VPN", and the BitString in the BIER header will contain the corresponding bit of PE2.
  • Step 408 The packet is sent to the multicast service layer by sending the BIER header locally on the PE2 according to the BIER forwarding process.
  • the PE2 knows the packet according to the value of the packet type field encapsulated in the BIER header, Multicast global VPN.
  • the BIER header is followed by the global VPN id information.
  • the PE2 node removes the BIER header and the global VPN id 100, the PE2 node continues to forward the remaining payloads in the multicast VRF routing table corresponding to the global VPN id 100, and the packets are sent to the D node.
  • FIG. 7 is a network topology diagram of the scenario of the multicast VPN cross-domain option B (option B) in this embodiment.
  • no VRF instance is created on the ASBR1 and ASBR2 nodes.
  • step 501 the global VPN identifier is assigned to the VRF_A on the PE1 and the PE2, and is recorded as the global VPN id 100, and the corresponding multicast VRF instance is created.
  • step 502 the "global VPN id forwarding capability" is explicitly configured on the ASBR1 and the ASBR2.
  • the PE1 node advertises the BGP I-PMSI A-D or S-PMSI A-D route to the ASBR1 node, and sets the tunnel type to "BIER with global VPN" in the PTA, and includes the global VPN id 100.
  • the other processing may be performed according to the process defined in RFC6513, so that the corresponding multicast receiver set for the specific multicast stream of the VRF_A can be determined as the ⁇ ASBR1 ⁇ on the PE1 node, and the S node also determines that the PE1 is the receiving end of the corresponding multicast stream. one.
  • step 504 the ASBR1 node continues to advertise the BGP I-PMSI A-D or S-PMSI A-D route to the ASBR2 node, and sets the tunnel type to "No tunnel information present" (refer to RFC6514) and includes the global VPN id 100.
  • Other processing can be performed in accordance with the process defined in RFC6513.
  • the ASBR1 node establishes an entry with the global VPN id 100 as the key value in the "global VPN id forwarding table", and the entry includes the corresponding multicast receiving end set as ⁇ ASBR2 ⁇ .
  • step 505 the ASBR2 node continues to advertise the BGP I-PMSI A-D or S-PMSI A-D route to the PE2 node, and sets the tunnel type to "BIER with global VPN" and includes the global VPN id 100.
  • Other processing can be performed in accordance with the process defined in RFC6513.
  • the ASBR2 node establishes an entry with the global VPN id 100 as the key value in the "global VPN id forwarding table", and the entry includes the corresponding multicast receiving end set as ⁇ PE2 ⁇ .
  • Step 506 PE1 receives the specific multicast stream of the S, and searches for the S-PMSI AD or I-PMSI AD route in the multicast VRF routing table corresponding to the locally maintained VRF_A instance to match the packet to be transmitted, and the matched route. If the PTA indicates that the tunnel type is "BIER with global VPN", the global VPN id of the route is first pushed into the packet, and then the BIER header is encapsulated and then forwarded. The message type field encapsulated in the BIER header will be set to "Multicast global VPN", and the BitString in the BIER header will contain the corresponding bit of ASBR1.
  • Step 507 The packet is sent to the multicast service layer by sending the BIER header locally on the ASBR1 according to the BIER forwarding process.
  • the ASBR1 knows the packet according to the value of the packet type field encapsulated in the BIER header, Multicast global VPN.
  • the BIER header is followed by the global VPN id information.
  • the ASBR1 finds the entry with the global VPN id 100 as the key value in the global VPN id forwarding table according to the global VPN id 100. The next hop is based on the forwarding information of the entry. If the packet is forwarded, the packet will be sent to the ASBR2 node, and the protocol type field in the corresponding Layer 2 encapsulation will be set to Multicast global VPN.
  • Step 508 After receiving the packet, the ASBR2 knows the global VPN id information after the Layer 2 encapsulation in the packet according to the protocol type "Multicast global VPN" in the Layer 2 header.
  • the ASBR2 node removes the packet from the Layer 2 encapsulation and then finds the entry with the global VPN id 100 as the key value in the global VPN id forwarding table according to the global VPN id 100.
  • the BIER header After the BIER header is encapsulated, it is forwarded to PE2.
  • the packet type field encapsulated in the BIER header is set to "Multicast global VPN", and the BitString in the BIER header will contain the corresponding bit of PE2.
  • the packet is sent to the multicast service layer after the BIER header is removed from the local device according to the BIER forwarding process.
  • the PE2 knows the packet according to the value of the encapsulated packet type field in the BIER header.
  • the BIER header is followed by the global VPN id information.
  • the PE2 continues to forward the remaining payloads in the multicast VRF routing table corresponding to the global VPN id 100, and the packets are sent to the D node.
  • FIG 8 is a network topology diagram of the scenario of the multicast VPN cross-domain option C (option C) in this embodiment.
  • the VRF instance is not created on the ASBR1 and ASBR2 nodes, and the VRF_A is directly exchanged between PE1 and PE2.
  • A-D route is directly interacted between PE1 and PE2.
  • a global VPN identifier is assigned to the VRF_A on both the PE1 and the PE2, and is recorded as a global VPN id 100, and a corresponding multicast VRF instance is created.
  • the ASBR2 advertises the BFR prefix and the BFR-id of the PE2 to the ASBR1 through the EBGP (External Border Gateway Protocol).
  • the ASBR1 advertises to the PE1 through the Internal Border Gateway Protocol (IBGP).
  • IBGP Internal Border Gateway Protocol
  • the PE1 node advertises the BGP I-PMSI A-D or S-PMSI A-D route to the PE2 node, and sets the tunnel type to "BIER with global VPN" in the PTA, and includes the global VPN id 100.
  • the other processing may be performed according to the process defined in RFC6513, so that the PE1 node can determine the corresponding multicast receiving end set for the specific multicast stream of the VRF_A as ⁇ PE2 ⁇ , and the S node also determines that the PE1 is the receiving end of the corresponding multicast stream. one.
  • Step 604 The BFIR receives the specific multicast stream of the S, and searches for the S-PMSI AD or I-PMSI AD route in the multicast VRF routing table corresponding to the locally maintained VRF_A instance to match the packet to be transmitted, and the matched route If the PTA indicates "BIER with global VPN", the global VPN id of the route is first pushed into the packet, and then the BIER header is encapsulated and then forwarded.
  • the packet type field encapsulated in the BIER header will be set to "Multicast global VPN", and the BitString in the BIER header will contain the corresponding bit of PE2.
  • Step 605 The packet is sent to the multicast service layer after being removed from the BIER header on the PE2 according to the conventional BIER forwarding process.
  • PE2 takes the value of Multicast global VPN. It is known that the BIER header in the packet is the global VPN id information.
  • the PE2 node After the PE2 node removes the BIER header and the global VPN id100, the PE2 node continues to forward the remaining payloads in the multicast VRF routing table corresponding to the global VPN id 100, and the packets are sent to the D node.
  • the network of Figure 8 corresponds in its entirety to the basic multicast VPN of Figure 1, where PE1 corresponds to BFIR and PE2 corresponds to PFER.
  • the embodiment of the present invention further provides a computer readable storage medium having stored thereon a computer program, which when executed by a processor, implements processing of any of the methods described in the above embodiments of the present invention.
  • Such software may be distributed on a computer readable medium, which may include computer storage media (or non-transitory media) and communication media (or transitory media).
  • computer storage medium includes volatile and nonvolatile, implemented in any method or technology for storing information, such as computer readable instructions, data structures, program modules or other data. Sex, removable and non-removable media.
  • Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridge, magnetic tape, magnetic disk storage or other magnetic storage device, or may Any other medium used to store the desired information and that can be accessed by the computer.
  • communication media typically includes computer readable instructions, data structures, program modules, or other data in a modulated data signal, such as a carrier wave or other transport mechanism, and can include any information delivery media. .
  • the bearer method and device for a multicast virtual private network provided by the embodiments of the present invention have the following beneficial effects: packet forwarding is implemented by using a global VPN identifier.
  • the forwarding mechanism is simpler and easier to implement and deploy.

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Abstract

在本发明实施例中提供了一种组播虚拟专用网络的承载方法和设备，其中，该方法包括：接入VRF的BFIR为组播VRF分配全局VPN标识，向接入组播VRF的BFER通告路由时携带全局VPN标识；BFIR收到组播VRF的报文后，为报文封装BIER头并进行转发，转发的报文中携带全局VPN标识。BFER为组播VRF分配全局VPN标识，并记录具有全局VPN标识的报文的转发信息；BFER收到具有全局VPN标识的报文后，移除报文的BIER头，查找转发信息并进行报文转发。本申请转发机制更简单，更容易实施和部署。

Description

一种组播虚拟专用网络的承载方法和设备 技术领域
本发明涉及数据通信领域，更具体地，涉及一种组播虚拟专用网络的承载方法和设备。
背景技术
BIER(Bit Indexed Explicit Replication，位索引显式复制)描述了组播报文转发的一种新的架构，为组播数据报文在组播域中提供最优路径转发。不需要使用协议建立组播分发树，也不需要中间节点维护任何流状态。当组播报文从域外到达BFIR(Bit-Forwarding Ingress Router，位转发入口路由器)时，BFIR先确定报文将在哪个BIER SD(sub-domain，子域)内发送及发往哪些BFER(Bit-Forwarding Egress Router，位转发出口路由器)，然后在报文头中插入“BIER header”，其中包含一个位串(BitString)，BitString的每一位表示相应BFER的BFR-id(Bit-Forwarding Egress Router Identifier位转发路由器索引)。
标准草案draft-ietf-bier-mvpn-06描述了BIER类型的运营商隧道(P-tunnel)作为组播VPN(Virtual Private Network：虚拟专用网络)的公网承载方法，该方法使用上游分配MPLS标签(upstream-assigned MPLS label)的方式，因为BIER属于P节点复制技术，即BIER封装的组播VRF(Virtual Routing Forwarding,VPN路由转发)标签对于所有出口(egress)PE(Provider Edge，网络侧边缘设备)必须相同。
然而在实际网络部署中，上游分配MPLS(Multi-Protocol Label Switching，多协议标签交换)标签的方式并没有得到广泛应用，主要的原因是许多设备的转发芯片不支持维护种类繁多的特定上下文标签空间，特定上下文标签空间的标识可能是一个隧道标识(tunnel id)、一个IP地址、一个MPLS标签、一个VLAN(Virtual Local Area Network，虚拟局域网)标识，或者draft-ietf-bier-mvpn-06所定义的BFIR标识等等任意信息，取 决于不同的应用场景，这么多的标识信息看似灵活，实际上对于表项空间资源紧张的转发芯片是行不通的。相关技术也缺少对上下文标签空间标识的约束与统一规范，在此前提下，很多设备选择不支持上游分配MPLS标签这种特性，也就无法实现基于BIER的组播VPN方法。
发明内容
本发明实施例提供了一种组播虚拟专用网络VPN的承载方法，包括：
接入组播虚拟专用网络路由转发VRF的位转发入口路由器BFIR为所述组播VRF分配全局VPN标识，向接入所述组播VRF的位转发出口路由器BFER通告路由时携带所述全局VPN标识；所述BFIR收到所述组播VRF的报文后，为所述报文封装位索引显式复制BIER头并进行转发，其中，转发的报文中携带所述全局VPN标识。
本发明实施例还提供了一种位转发入口路由器，包括：标识分配模块，设置为为本位转发入口路由器BFIR接入的组播虚拟专用网络路由转发VRF分配全局VPN标识；路由通告模块，设置为向接入所述组播VRF的位转发出口路由器BFER通告路由，所述路由中携带所述全局VPN标识；报文转发模块，设置为在收到所述组播VRF的报文后，为所述报文封装位索引显式复制BIER头并进行转发，其中，转发的报文中携带所述全局VPN标识。
本发明实施例还提供了一种组播虚拟专用网络VPN的承载方法，包括：接入组播虚拟专用网络路由转发VRF的位转发出口路由器BFER为所述组播VRF分配全局VPN标识，并记录具有所述全局VPN标识的报文的转发信息；所述BFER收到具有所述全局VPN标识的报文后，移除所述报文的BIER头，查找所述转发信息并进行报文转发。
本发明实施例还提供了一种位转发出口路由器，包括：标识分配模块，设置为为本位转发入口路由器BFIR接入的组播虚拟专用网络路由转发VRF分配全局VPN标识；信息记录模块，设置为记录具有所述全局VPN标识的报文的转发信息；报文转发模块，设置为在收到具有所述全局VPN 标识的报文后，移除所述报文的BIER头，查找所述转发信息并进行报文转发。
本发明实施例还提供一种位转发入口路由器，包括存储器、处理器及存储在所述存储器上并可在所述处理器上运行的计算机程序，所述处理器执行所述计算机程序时实现本实施例方法的处理。
本发明实施例还提供了一种计算机可读存储介质，其上存储有计算机程序，所述计算机程序被处理器执行时实现本实施例方法的处理。
上述实施例方案通过全局VPN标识来实现报文转发。转发机制更简单，更容易实施和部署。
附图说明
图1是本发明实施例一基本组播VPN场景的网络拓扑图；
图2是本发明实施例一BFIR侧的组播VPN承载方法的流程图；
图3是本发明实施例一位转发入口路由器的模块图；
图4是本发明实施例二BFER侧的组播VPN承载方法的流程图；
图5是本发明实施例二位转发出口路由器的模块图；
图6是本发明实施例五组播VPN跨域选项A(option A)场景的网络拓扑图；
图7是本发明实施例六组播VPN跨域选项B(option B)场景的网络拓扑图；
图8是本发明实施例七组播VPN跨域选项C(option C)场景的网络拓扑图。
具体实施方式
为使本发明的目的、技术方案和优点更加清楚明白，下文中将结合附图对本发明的实施例进行详细说明。需要说明的是，在不冲突的情况下，本申请中的实施例及实施例中的特征可以相互任意组合。
实施例一
本实施例提供一种组播VPN的承载方法，组播VPN的承载方法涉及组播VPN报文的转发处理，以及为实现报文转发的相关处理，如标识分配、路由通告等。
图1为基本组播VPN场景的网络拓扑图，其中BFIR接入VRF_A组播源S，BFER1～BFER3分别接入VRF_A的组播接收端rcv1～rcv3，图中还示出了位于BFIR和BFER之间的BFR(Bit-Forwarding Router，位转发路由器)。其中，VRF_A表示名称为A的组播VRF实例。图中只是一个示例，在其他示例中，BFIR与S不一定是直连的，BFIR只需要知道其左侧入接口连向组播源即可。BFER与组播接收端的连接也是如此，两者并不一定是直连，BFER只需要知道其右侧出接口连接组播接收端即可。BFIR和BFER均属于接入组播VRF的PE节点。
图2是本实施例BFIR侧的组播VPN承载方法的流程图，包括：
步骤110，接入组播VRF的BFIR为所述组播VRF分配全局VPN标识，向接入所述组播VRF的位转发出口路由器BFER通告路由时携带所述全局VPN标识；
在SDN(Software Defined Network，软件定义网络)中，对组播VPN业务，为各边界PE上相同的组播VRF分配相同的全局VPN标识(global VPN id)。即在接入某一组播VRF的PE上，使用全局VPN标识来唯一标识该组播VRF。组播VPN的全局VPN标识可以通过控制器统一分配并向各边界PE下发，或者由管理员在各边界PE上静态配置，或者其他方式分配。
本实施例中，扩展关于使用BIER作为P-tunnel的BGP(边界网关协议)I-PMSI(Inclusive P-Multicast Service Interface，包含模式运营商组播业务接口)A-D(auto-discovery，自动发现)或S-PMSI(Selective P-Multicast Service Interface，选择性运营商组播业务接口)A-D通告，在通告(或称 为通告消息)中携带组播VRF的全局VPN标识(global VPN id)。在一个示例中，BFIR向接入组播VRF的BFER通告路由时，可以将所述组播VRF的全局VPN标识携带在通告的路由的MPLS标签字段。
本实施例通告的BGP I-PMSI A-D或S-PMSI A-D路由的PMSI(P-Multicast Service Interface，运营商组播业务接口)隧道属性(Tunnel Attribute)包括以下字段：
隧道类型(Tunnel Type)：使用扩展的值表示“BIER with global VPN”类型。
隧道标识(Tunnel Identifier)：包括以下两个信息：BIER sub-domain id,BFIR-Prefix。
MPLS标签(MPLS Label)：该字段在RFC6514中一般设置为某个标签值，本实施例则设置为“global VPN id”。
标志(Flags)：包含两个标志位：1)“Leaf Info Required”标志位，其定义同RFC6514；2)“Leaf Info Required per Flow(LIR-pF)”标志位，其定义同draft-ietf-bess-mvpn-expl-track。
可以看到，本实施例在rfc6514定义的PMSI Tunnel Attribute的基础上，对隧道类型进行了扩展，增加了一种新的隧道类型，本申请称其为“扩展的协议类型”。该扩展的隧道类型用于指示隧道基于使用全局VPN标识的BIER，也即本实施例改进的BIER。该扩展的隧道类型在本实施例称之为“BIER with global VPN”类型，但本申请不局限于此，具体名称完全可以使用其他的名称。“BIER with global VPN”类型可以使用Tunnel Type字段的扩展的值来表示。
步骤120，所述BFIR收到所述组播VRF的报文后，为所述报文封装BIER头并进行转发，其中，转发的报文中携带所述全局VPN标识。
本实施例中，所述BFIR为所述组播VRF创建实例，在该实例对应的组播VRF路由表的路由中，使用扩展的隧道类型指示隧道基于使用全局VPN标识的BIER；所述BFIR收到所述组播VRF的报文后，先从所述组 播VRF路由表中查找到与所述报文匹配的路由，确定所述路由的隧道类型为所述扩展的隧道类型时，将所述全局VPN标识压入所述报文；之后，再为所述报文封装所述BIER头并进行转发。
本实施例中，所述BFIR向接入所述组播VRF的BFER通告路由时，还将所述路由中的隧道类型设置为扩展的隧道类型，所述扩展的隧道类型用于指示隧道基于使用全局VPN标识的BIER。
在另一实施例中，所述BFIR并不为所述组播VRF创建实例，为了实现转发，所述BFIR为所述组播VRF分配全局VPN标识后，在转发表中建立以所述全局VPN标识为键值的表项，在所述表项中记录携带所述全局VPN标识的报文的转发信息；所述BFIR收到所述组播VRF的报文后，移除所述报文的二层头，根据所述二层头中扩展的协议类型确定所述二层头后包括全局VPN标识时，从所述转发表中查找到所述转发信息；之后，再为所述报文封装BIER头并进行转发。在该另一实施例中，所述BFIR向接入所述组播VRF的BFER通告路由时，也可以携带所述全局VPN标识，并将所述路由中的隧道类型设置为上述扩展的隧道类型。
在该另一实施例中，对二层封装的协议类型进行扩展，上游节点(如另一个域的BFER)在向所述BFIR转发所述组播VRF的报文时，在二层头中使用扩展的协议类型来指示二层头后包括全局VPN标识，该扩展的协议类型可以通过协议类型字段扩展的一种取值来表示，该扩展的协议类型可称为“Multicast global VPN”，但本申请对其名称并不做限制。对报文做上述封装后，所述BFIR可根据所述报文二层头中扩展的协议类型确定所述二层头后包括全局VPN标识，此时无需再压入所述全局VPN标识。二层封装是对移除了BIER header后的报文所做的数据链路层的封装，扩展二层头中的协议类型，可以支持封装和解析组播VRF报文的全局VPN标识，下一节点在解析报文的二层头时，根据二层头中的协议类型“Multicast global VPN”就可以知道二层头之后是一个global VPN id。
在本实施例及该另一实施例中，均对BIER头中的报文类型进行扩展， 所述BFIR为所述报文封装BIER头时，将所述BIER头中的报文类型设置为扩展的报文类型，所述扩展的报文类型用于指示报文中携带组播VRF的全局VPN标识。扩展BIER头(header)中的报文类型，可以支持在组播VRF报文中封装和解析组播VRF报文的全局VPN标识。本实施例在draft-ietf-bier-mpls-encapsulation-07中定义的BIER头的基础上，对其中的Proto字段新增一种取值来表示上述扩展的报文类型，该扩展的报文类型可称为“Multicast global VPN”，但本申请并不局限于此。
本实施例还提供一种位转发入口路由器，如图3所示，包括：
标识分配模块10，设置为为本位转发入口路由器BFIR接入的组播虚拟专用网络路由转发VRF分配全局VPN标识；
路由通告模块20，设置为向接入所述组播VRF的位转发出口路由器BFER通告路由，所述路由中携带所述全局VPN标识；
报文转发模块30，设置为在收到所述组播VRF的报文后，为所述报文封装位索引显式复制BIER头并进行转发，其中，转发的报文中携带所述全局VPN标识。
本实施例中，
所述位转发入口路由器还包括：实例创建模块，设置为为所述组播VRF创建实例，在该实例对应的组播VRF路由表的路由中，使用扩展的隧道类型指示隧道基于使用全局VPN标识的BIER；
所述报文转发模块收到所述组播VRF的报文后，还设置为从所述组播VRF路由表中查找到与所述报文匹配的路由，确定所述路由的隧道类型为所述扩展的隧道类型时，将所述全局VPN标识压入所述报文；之后，再为所述报文封装所述BIER头并进行转发。
本实施例中，
所述路由通告模块向接入所述组播VRF的BFER通告路由时，还将 所述路由中的隧道类型设置为所述扩展的隧道类型。
本实施例中，
所述BFIR向接入所述组播VRF的BFER通告路由时，将所述全局VPN标识携带在通告的路由的多协议标签交换MPLS标签字段。
在另一实施例中，
所述位转发入口路由器包括标识分配模块、路由通告模块和报文转发模块，其中，标识分配模块和路由通告模块的功能可以与本实施例相同。所述位转发入口路由器还包括：转发表维护模块，设置为在转发表中建立以所述全局VPN标识为键值的表项，在所述表项中记录携带所述全局VPN标识的报文的转发信息；所述报文转发模块收到所述组播VRF的报文后，移除所述报文的二层头，根据所述二层头中扩展的协议类型确定所述二层头后包括全局VPN标识时，从所述转发表中查找到所述转发信息；之后，再为所述报文封装BIER头并进行转发。
在本实施例及该另一实施例中，
所述报文转发模块为所述报文封装BIER头时，均将所述BIER头中的报文类型设置为扩展的报文类型，所述扩展的报文类型用于指示报文中携带组播VRF的全局VPN标识。
实施例二
本实施例的网络拓扑可参见图1。实施例一是从BFIR侧描述组播VPN的承载方法，本实施例则是从BFER侧来描述组播VPN的承载方法。在理解本实施例方法时，可以参见实施例一中描述的BFIR侧的处理。
本实施例BFER侧的组播VPN承载方法的流程如图4所示，包括：步骤210，接入组播VRF的BFER为所述组播VRF分配全局VPN标识，并记录具有所述全局VPN标识的报文的转发信息；步骤220，所述BFER 收到具有所述全局VPN标识的报文后，移除所述报文的BIER头，查找所述转发信息并进行报文转发。因为所述全局VPN标识是所述组播VPN的唯一标识，上述具有所述全局VPN标识的报文也即所述组播VRF的报文。
本实施例中，所述BFER创建所述组播VRF的实例，global VPN id用于节点内部区分不同组播VRF实例对应的组播VRF路由表。在所述实例对应的组播VRF路由表的路由中记录具有所述全局VPN标识的报文的转发信息；所述BFER查找所述转发信息并进行报文转发，包括：所述BFER确定所述BIER头中的报文类型为扩展的报文类型时，将所述BIER头后的全局VPN标识移除，将剩下的载荷在所述组播VRF路由表中查表转发，所述扩展的报文类型用于指示报文中携带组播VRF的全局VPN标识。
在另一实施例中，所述BFER不为所述组播VRF创建实例，所述BFER为所述组播VRF分配全局VPN标识后，在转发表中建立以所述全局VPN标识为键值的表项，在所述表项中记录带有所述全局VPN标识的报文的转发信息；而所述BFER收到具有所述全局VPN标识的报文后，移除所述报文的BIER头，确定所述BIER头中的报文类型为扩展的报文类型时，根据所述BIER头后的所述全局VPN标识到所述转发表中查找所述转发信息并进行报文转发，所述扩展的报文类型用于指示报文中携带组播VRF的全局VPN标识。在该另一实施例中，所述BFER进行报文转发，包括：所述BFER对所述报文进行二层封装时，将二层头中的协议类型设置为扩展的协议类型，所述扩展的协议类型用于指示二层头之后有一个全局VPN标识。
本实施例还提供了一种位转发出口路由器，如图5所示，包括：
标识分配模块50，设置为为本位转发入口路由器BFIR接入的组播虚拟专用网络路由转发VRF分配全局VPN标识；
信息记录模块60，设置为记录具有所述全局VPN标识的报文的转发信息；
报文转发模块70，设置为在收到具有所述全局VPN标识的报文后，移除所述报文的BIER头，查找所述转发信息并进行报文转发。
本实施例中，
所述信息记录模块记录具有所述全局VPN标识的报文的转发信息，包括：创建所述组播VRF的实例，在所述实例对应的组播VRF路由表的路由中，记录具有所述全局VPN标识的报文的转发信息；
所述报文转发模块查找所述转发信息并进行报文转发，包括：确定所述BIER头中的报文类型为扩展的报文类型时，将所述BIER头后的全局VPN标识移除，将剩下的载荷在所述组播VRF路由表中查表转发，所述扩展的报文类型用于指示报文中携带组播VRF的全局VPN标识。
在另一实施例中，
所述信息记录模块记录具有所述全局VPN标识的报文的转发信息，包括：在转发表中建立以所述全局VPN标识为键值的表项，在所述表项中记录带有所述全局VPN标识的报文的转发信息；
所述报文转发模块查找所述转发信息并进行报文转发，包括：确定所述BIER头中的报文类型为扩展的报文类型时，根据所述BIER头后的所述全局VPN标识到所述转发表中查找所述转发信息并进行报文转发，所述扩展的报文类型用于指示报文中携带组播VRF的全局VPN标识。
在该另一实施例中，所述报文转发模块进行报文转发，包括：对所述报文进行二层封装时，将二层头中的协议类型设置为扩展的协议类型，所述扩展的协议类型用于指示二层头之后有一个全局VPN标识。
本实施例和实施例二描述的上述方案，不需要转发芯片建立种类繁多的上下文表空间，通过全局VPN标识，就可以使用路由器支持VRF的基 本功能(例如VRF路由表实例或转发表)实现报文转发。因此转发机制更简单，更容易实施和部署。可以用于替代上游分配MPLS标签的方式。
实施例三
本实施例基于基本组播VPN场景的网络拓扑图，对组播VPN承载方法的整体流程进行描述。
第一步
在接入组播VRF的PE节点(包括BFIR与BFER)上，通过控制器或者静态配置为所述组播VRF分配global VPN id；
global VPN id一般默认用于节点内部区分不同组播VRF实例对应的组播VRF路由表，适用于那些能够本地创建组播VRF实例的节点(如基本组播VPN场景下的ingress PE与egress PE节点)。一般情况下，仅需要为一个组播VRF分配一个全局唯一的global VPN id。不过为了支持更多的应用场景，也可以为一个组播VRF分配多个全局唯一的global VPN id，比如在一个示例中，根据策略，所述组播VRF下不同的I-PMSI(P-Multicast Service Interface，运营商组播业务接口)或S-PMSI A-D route可以使用不同的global VPN id。
在另一实施例中，可以为global VPN id引入新的功能，适用于那些不创建组播VRF实例的节点(如组播VPN的option B跨域场景下的ASBR节点)，在转发表中直接以global VPN id为键值建立表项，表项中给出相应的转发信息，以指导携带有global VPN id的报文向相应的下一跳转发，该转发表也可以称之为“global VPN id转发表”。global VPN id的这两个功能一般是互斥的。
在一个示例中，用global VPN id区分整张组播VPN路由表是默认的，无需显式配置，而要以global VPN id为键值建立表项，则需要在节点上显式配置以global VPN id为键值建立表项的能力(即使能该能力)，或称为 “global VPN id转发能力”。
第二步
接入所述VRF组播源的BFIR节点向其它接入所述VRF组播接收者的BFER节点通告BGP I-PMSI A-D或S-PMSI A-D路由，在其中的PTA(PMSI Tunnel Attribute，PMSI隧道属性)中包含组播VRF的global VPN id的信息，并在PTA中设置tunnel type为“BIER with global VPN”即“使用全局VPN的BIER”，该tunnel type有别于draft-ietf-bier-mvpn-06中定义的类型“BIER”。
BFIR节点通告S-PMSI A-D或I-PMSI A-D路由的其它处理可按照RFC6513定义的流程执行，使得BFIR节点上可以为特定的VRF组播流确定相应的BFER节点集合。
第三步
报文转发时，BFIR节点查找S-PMSI A-D或I-PMSI A-D路由以匹配需要传输的报文，如果匹配的路由的PTA表明隧道类型是“BIER with global VPN”，则将该路由的global VPN id先压入(push或Insert)报文，如在原报文前添加global VPN id，然后再封装BIER header后转发。其中，BIER header中所封装的报文类型设置为扩展的报文类型，即“Multicast global VPN”。
第四步
BFER节点收到BIER封装的报文时，如果发现报文需要在本地移除BIER header后上送至组播业务层，则根据BIER header中封装的报文类型为“Multicast global VPN”，知道报文中BIER header之后就是global VPN id。BFER节点将报文移除BIER header与global VPN id后，继续将剩下的载荷在该global VPN id对应的组播VRF路由表中查表转发。
在另一实施例中，如果BFER节点上显式配置了“global VPN id转发能力”，则BFER节点收到BIER封装的报文，将报文移除BIER header后，根据BIER header后的global VPN id查找“global VPN id转发表”获取相 应的转发信息，将报文向相应的下一跳转发。
本实施例不需要转发芯片建立种类繁多的上下文表空间，只是需要建立VRF路由表实例，而建立VRF路由表实例是路由器支持VRF的基本功能。因此转发机制更简单，更容易实施和部署。可以用于替代上游分配MPLS标签的方式，完善现有标准。
实施例四
图1为本实施例基本组播VPN场景的网络拓扑图，其中BFIR接入VRF_A组播源S，BFER1～BFER3分别接入VRF_A的组播接收端rcv1～rcv3。其中，VRF_A表示名称为A的VRF实例。
本实施例方法的主要步骤如下：
步骤301，BFIR与BFER1～BFER3为VRF_A分配全局唯一的全局VPN标识(记为global VPN id 100)，并创建VRF_A的实例，包括建立VRF_A的组播VRF路由表。
步骤302，BFIR节点向各BFER节点通告BGP I-PMSI A-D或S-PMSI A-D路由，在其中的PTA中设置tunnel type为“BIER with global VPN”，并包含global VPN id 100。通告路由的其它处理可按照RFC6513定义的流程执行，使得BFIR节点上可以为VRF_A的特定组播流确定相应的组播接收端集合为{BFER1,BFER2,BFER3}，另外S节点也确定BFIR是相应的组播流的接收端之一。
步骤303，BFIR收到S的特定组播流，在本地维护的VRF_A实例对应的组播VRF路由表中查找S-PMSI A-D或I-PMSI A-D路由以匹配需要传输的报文，本实施例中，匹配到的路由的PTA表明隧道类型是“BIER with global VPN”，则将该路由的global VPN id先压入报文，然后再封装BIER header后转发。BIER header中所封装的报文类型字段将设置为“Multicast global VPN”，BIER header中的BitString中将包含 BFER1～BFER3。
步骤304，报文按照BIER转发流程，分别在BFER1～BFER3上本地移除BIER header后上送至组播业务层。以BFER1为例，BFER1根据BIER header封装的报文类型字段的取值“Multicast global VPN”，知道报文中BIER header之后就是global VPN id，于是将报文移除BIER header与global VPN id 100后，继续将剩下的载荷在global VPN id 100对应的组播VRF路由表中查表转发，报文将发给rcv1节点。BFER2与BFER3节点的处理类似。
实施例五
图6所示是本实施例组播VPN跨域选项A(option A)场景的网络拓扑图，该场景实际上是由两个基本组播VPN拓扑拼接起来，图中示出了组播源S、组播接收端D，自治系统(Autonomous System，AS)的两个边缘设备节点PE1和PE2，以及两个ASBR(Autonomous System Boundary Router，自治系统边界路由器)节点：ASBR1与ASBR2，ASBR1与ASBR2互为对方的VRF_A客户。图中，AS1网络中的PE1对应于BFIR，ASBR1对应于BFER；AS2网络中的ASBR2对应BFIR，ASBR2对应于BFER。
本实施例组播VPN的承载方法包括：
步骤401，PE1、PE2、ASBR1、ASBR2为VRF_A分配全局VPN标识(记为global VPN id 100)，并创建VRF_A的实例，包括建立VRF_A的组播VRF路由表。
步骤402，PE1向ASBR1通告BGP I-PMSI A-D或S-PMSI A-D路由，在其中的PTA中设置tunnel type为“BIER with global VPN”，并包含global VPN id 100。其它处理可按照RFC6513定义的流程执行，使得PE1节点上可以为VRF_A的特定组播流确定相应的组播接收端集合为{ASBR1}，另外S节点也确定PE1是相应的组播流的接收端之一。
步骤403，ASBR1节点继续向ASBR2节点通告BGP I-PMSI A-D或 S-PMSI A-D路由，在其中的PTA中设置tunnel type为“No tunnel information present”(参见RFC6514)。其它处理可按照RFC6513定义的流程执行，使得ASBR1节点上可以为VRF_A的特定组播流确定相应的组播接收端集合为{ASBR2}。
ASBR1与ASBR2之间也可以使能PIM协议，通过发送相应的PIM消息使得ASBR1节点上可以为VRF_A的特定组播流确定相应的组播接收端集合为{ASBR2}。这种方式是现有标准内容，不再赘述。
步骤404，ASBR2节点继续向PE2节点通告BGP I-PMSI A-D或S-PMSI A-D路由，在其中的PTA中设置tunnel type为“BIER with global VPN”，并包含global VPN id 100。其它处理可按照RFC6513定义的流程执行，使得ASBR2节点上可以为VRF_A的特定组播流确定相应的组播接收端集合为{PE2}。
需要说明的是，ASBR2可以独立自主的选择tunnel type，不一定要与其它域的tunnel type相同。本实施例中ASBR2具有BIER转发能力，所以选择BIER转发机制。
步骤405，PE1收到S的特定组播流，在本地维护的VRF_A实例对应的组播VRF路由表中查找S-PMSI A-D或I-PMSI A-D路由以匹配需要传输的报文，匹配到的路由的PTA表明隧道类型是“BIER with global VPN”，则将该路由的global VPN id先压入报文，然后再封装BIER header后转发。BIER header中所封装的报文类型字段将设置为“Multicast global VPN”，BIER header中的BitString中将包含ASBR1相应的位。
步骤406，报文按照常规的BIER转发流程，在ASBR1上本地移除BIER header后上送至组播业务层，ASBR1根据BIER header中的封装的报文类型字段取值为“Multicast global VPN”，知道报文中BIER header之后就是global VPN id信息。ASBR1节点于是将报文移除BIER header与global VPN id 100后，继续将剩下的载荷在global VPN id 100对应的组播VRF路由表中查表转发，报文将发给ASBR2节点。
报文从ASBR1向ASBR2转发时，是传统的三层组播IP转发，不需要BIER封装。
步骤407，ASBR2收到ASBR1的特定组播流，在本地维护的VRF_A实例对应的组播VRF路由表中查找S-PMSI A-D或I-PMSI A-D路由以匹配需要传输的报文，匹配的路由的PTA表明是“BIER with global VPN”，则将该路由的global VPN id先压入报文，然后再封装BIER header后转发。BIER header中所封装的报文类型字段将设置为“Multicast global VPN”，BIER header中的BitString中将包含PE2相应的位。
步骤408，报文按照BIER转发流程，在PE2上本地移除BIER header后上送至组播业务层，PE2根据BIER header中封装的报文类型字段的取值“Multicast global VPN”，知道报文中BIER header之后就是global VPN id信息。PE2节点于是将报文移除BIER header与global VPN id 100后，继续将剩下的载荷在global VPN id 100对应的组播VRF路由表中查表转发，报文将发给D节点。
实施例六
图7所示是本实施例组播VPN跨域选项B(option B)场景的网络拓扑图，该场景中，ASBR1与ASBR2节点上将不创建VRF实例。
本实施例组播VPN的承载方法包括：
步骤501，PE1、PE2节点上均为VRF_A分配全局VPN标识，记为global VPN id 100，并创建相应的组播VRF实例。
步骤502，ASBR1、ASBR2节点上分别显式配置“global VPN id转发能力”。
本步骤中，可以在设备上通过命令配置打开使能“global VPN id”转发能力的开关，来实现显式配置“global VPN id转发能力”。
步骤503，PE1节点向ASBR1节点通告BGP I-PMSI A-D或S-PMSI A-D路由，在其中的PTA中设置tunnel type为“BIER with global VPN”，并包含global VPN id 100。其它处理可按照RFC6513定义的流程执行，使得PE1节点上可以为VRF_A的特定组播流确定相应的组播接收端集合为{ASBR1}，另外S节点也确定PE1是相应的组播流的接收端之一。
步骤504，ASBR1节点继续向ASBR2节点通告BGP I-PMSI A-D或S-PMSI A-D路由，在其中的PTA中设置tunnel type为“No tunnel information present”(参考RFC6514)，并包含global VPN id 100。其它处理可按照RFC6513定义的流程执行。
本实施例中，ASBR1节点在“global VPN id转发表”中建立以global VPN id 100为键值的表项，表项中包含相应的组播接收端集合为{ASBR2}。
步骤505，ASBR2节点继续向PE2节点通告BGP I-PMSI A-D或S-PMSI A-D路由，在其中的PTA中设置tunnel type为“BIER with global VPN”，并包含global VPN id 100。其它处理可按照RFC6513定义的流程执行。
本实施例中，ASBR2节点在“global VPN id转发表”中建立以global VPN id 100为键值的表项，表项中包含相应的组播接收端集合为{PE2}。
步骤506，PE1收到S的特定组播流，在本地维护的VRF_A实例对应的组播VRF路由表中查找S-PMSI A-D或I-PMSI A-D路由以匹配需要传输的报文，匹配到的路由的PTA表明隧道类型是“BIER with global VPN”，则将该路由的global VPN id先压入报文，然后再封装BIER header后转发。BIER header中所封装的报文类型字段将设置为“Multicast global VPN”，BIER header中的BitString中将包含ASBR1相应的位。
步骤507，报文按照BIER转发流程，在ASBR1上本地移除BIER header后上送至组播业务层，ASBR1根据BIER header中封装的报文类型字段的取值“Multicast global VPN”，知道报文中BIER header之后就是global VPN id信息。ASBR1节点将报文移除BIER header后，根据global  VPN id 100在“global VPN id转发表”中查找到以global VPN id 100为键值的表项，根据该表项的转发信息向下一跳转发，报文将发给ASBR2节点，且相应二层封装中的协议类型字段将设置为“Multicast global VPN”。
步骤508，ASBR2收到报文后，根据二层头中的协议类型“Multicast global VPN”，知道报文中二层封装之后就是global VPN id信息。ASBR2节点将报文移除二层封装后，根据global VPN id 100在“global VPN id转发表”中查找到以global VPN id 100为键值的表项，根据该表项的转发信息，为报文封装BIER header后向PE2转发。BIER header中所封装的报文类型字段设置为“Multicast global VPN”，BIER header中的BitString中将包含PE2相应的位。
步骤509，报文按照BIER转发流程，在PE2本地移除BIER header后上送至组播业务层，PE2根据BIER header中的封装的报文类型字段的取值“Multicast global VPN”，知道报文中BIER header之后就是global VPN id信息。PE2将报文移除BIER header与global VPN id 100后，继续将剩下的载荷在global VPN id 100对应的组播VRF路由表中查表转发，报文将发给D节点。
实施例七
图8所示是本实施例组播VPN跨域选项C(option C)场景的网络拓扑图，该场景中，ASBR1与ASBR2节点上将不创建VRF实例，直接在PE1与PE2之间交互VRF_A对应的S-PMSI A-D或I-PMSI A-D路由。A-D route是直接在PE1与PE2之间交互。
本实施例组播VRF的承载方法包括：
步骤601，PE1与PE2节点上均为VRF_A分配全局VPN标识，记为global VPN id 100，并创建相应的组播VRF实例。
步骤602，ASBR2将PE2的BFR prefix以及BFR-id通过EBGP (External Border Gateway Protocol：外部边界网关协议)通告给ASBR1，ASBR1继续通过IBGP(Internal Border Gateway Protocol，内部边界网关协议)通告给PE1。
步骤603，PE1节点向PE2节点通告BGP I-PMSI A-D或S-PMSI A-D路由，在其中的PTA中设置tunnel type为“BIER with global VPN”，并包含global VPN id 100。其它处理可按照RFC6513定义的流程执行，使得PE1节点上可以为VRF_A的特定组播流确定相应的组播接收端集合为{PE2}，另外S节点也确定PE1是相应的组播流的接收端之一。
步骤604，BFIR收到S的特定组播流，在本地维护的VRF_A实例对应的组播VRF路由表中查找S-PMSI A-D或I-PMSI A-D路由以匹配需要传输的报文，匹配的路由的PTA表明是“BIER with global VPN”，则将该路由的global VPN id先压入报文，然后再封装BIER header后转发。BIER header中所封装的报文类型字段将设置为“Multicast global VPN”，BIER header中的BitString中将包含PE2相应的位。
步骤605，报文按照常规的BIER转发流程，在PE2上本地移除BIER header后上送至组播业务层。PE2根据BIER header中的封装的报文类型字段取值为“Multicast global VPN”，知道报文中BIER header之后就是global VPN id信息。PE2节点于是将报文移除BIER header与global VPN id100后，继续将剩下的载荷在global VPN id 100对应的组播VRF路由表中查表转发，报文将发给D节点。
图8的网络整体上对应于图1中的基本组播VPN，其中的PE1对应于BFIR，PE2对应于PFER。
本发明实施例还提供了一种计算机可读存储介质，其上存储有计算机程序，所述计算机程序被处理器执行时实现如本发明上述实施例所述的任一方法的处理。
本领域普通技术人员可以理解，上文中所公开方法中的全部或某些步骤、系统、装置中的功能模块/单元可以被实施为软件、固件、硬件及其适当的组合。在硬件实施方式中，在以上描述中提及的功能模块/单元之间的划分不一定对应于物理组件的划分；例如，一个物理组件可以具有多个功能，或者一个功能或步骤可以由若干物理组件合作执行。某些物理组件或所有物理组件可以被实施为由处理器，如中央处理器、数字信号处理器或微处理器执行的软件，或者被实施为硬件，或者被实施为集成电路，如专用集成电路。这样的软件可以分布在计算机可读介质上，计算机可读介质可以包括计算机存储介质(或非暂时性介质)和通信介质(或暂时性介质)。如本领域普通技术人员公知的，术语计算机存储介质包括在用于存储信息(诸如计算机可读指令、数据结构、程序模块或其他数据)的任何方法或技术中实施的易失性和非易失性、可移除和不可移除介质。计算机存储介质包括但不限于RAM、ROM、EEPROM、闪存或其他存储器技术、CD-ROM、数字多功能盘(DVD)或其他光盘存储、磁盒、磁带、磁盘存储或其他磁存储装置、或者可以用于存储期望的信息并且可以被计算机访问的任何其他的介质。此外，本领域普通技术人员公知的是，通信介质通常包含计算机可读指令、数据结构、程序模块或者诸如载波或其他传输机制之类的调制数据信号中的其他数据，并且可包括任何信息递送介质。
工业实用性
如上所述，本发明实施例提供的一种组播虚拟专用网络的承载方法和设备具有以下有益效果：通过全局VPN标识来实现报文转发。转发机制更简单，更容易实施和部署。

Claims (22)

  1. 一种组播虚拟专用网络VPN的承载方法，包括：
    接入组播虚拟专用网络路由转发VRF的位转发入口路由器BFIR为所述组播VRF分配全局VPN标识，向接入所述组播VRF的位转发出口路由器BFER通告路由时携带所述全局VPN标识；
    所述BFIR收到所述组播VRF的报文后，为所述报文封装位索引显式复制BIER头并进行转发，其中，转发的报文中携带所述全局VPN标识。
  2. 如权利要求1所述的方法，其中：
    所述BFIR向接入所述组播VRF的BFER通告路由时携带所述全局VPN标识，包括：所述BFIR向接入所述组播VRF的BFER通告路由时，将所述全局VPN标识携带在通告的路由的多协议标签交换MPLS标签字段。
  3. 如权利要求1所述的方法，其中：
    所述方法还包括：所述BFIR为所述组播VRF创建实例，在所述实例对应的组播VRF路由表的路由中，使用扩展的隧道类型指示隧道基于使用全局VPN标识的BIER；
    所述BFIR收到所述组播VRF的报文后，所述方法还包括：所述BFIR从所述组播VRF路由表中查找到与所述报文匹配的路由，确定所述路由的隧道类型为所述扩展的隧道类型时，将所述全局VPN标识压入所述报文；之后，再为所述报文封装所述BIER头并进行转发。
  4. 如权利要求3所述的方法，其中：
    所述BFIR向接入所述组播VRF的BFER通告路由时，还将所述路由中的隧道类型设置为所述扩展的隧道类型。
  5. 如权利要求1所述的方法，其中：
    所述BFIR分配所述全局VPN标识后，所述方法还包括：所述BFIR 在转发表中建立以所述全局VPN标识为键值的表项，在所述表项中记录携带所述全局VPN标识的报文的转发信息；
    所述BFIR收到所述组播VRF的报文后，所述方法还包括：所述BFIR移除所述报文的二层头，根据所述二层头中扩展的协议类型确定所述二层头后包括全局VPN标识时，从所述转发表中查找到所述转发信息；之后，再为所述报文封装BIER头并进行转发。
  6. 如权利要求5所述的方法，其中：
    所述BFIR显式配置以全局VPN标识为键值建立表项的能力。
  7. 如权利要求1-6中任一所述的方法，其中：
    所述BFIR为所述报文封装BIER头，包括：将所述BIER头中的报文类型设置为扩展的报文类型，所述扩展的报文类型用于指示报文中携带组播VRF的全局VPN标识。
  8. 一种位转发入口路由器，包括：
    标识分配模块，设置为为本位转发入口路由器BFIR接入的组播虚拟专用网络路由转发VRF分配全局VPN标识；
    路由通告模块，设置为向接入所述组播VRF的位转发出口路由器BFER通告路由，所述路由中携带所述全局VPN标识；
    报文转发模块，设置为在收到所述组播VRF的报文后，为所述报文封装位索引显式复制BIER头并进行转发，其中，转发的报文中携带所述全局VPN标识。
  9. 如权利要求8所述的位转发入口路由器，其中：
    所述位转发入口路由器还包括：实例创建模块，设置为为所述组播VRF创建实例，在该实例对应的组播VRF路由表的路由中，使用扩展的隧道类型指示隧道基于使用全局VPN标识的BIER；
    所述报文转发模块收到所述组播VRF的报文后，还设置为从所述组 播VRF路由表中查找到与所述报文匹配的路由，确定所述路由的隧道类型为所述扩展的隧道类型时，将所述全局VPN标识压入所述报文；之后，再为所述报文封装所述BIER头并进行转发。
  10. 如权利要求9所述的位转发入口路由器，其中：
    所述路由通告模块向接入所述组播VRF的BFER通告路由时，还将所述路由中的隧道类型设置为所述扩展的隧道类型。
  11. 如权利要求8所述的位转发入口路由器，其中：
    所述位转发入口路由器还包括：转发表维护模块，设置为在转发表中建立以所述全局VPN标识为键值的表项，在所述表项中记录携带所述全局VPN标识的报文的转发信息；
    所述报文转发模块收到所述组播VRF的报文后，移除所述报文的二层头，根据所述二层头中扩展的协议类型确定所述二层头后包括全局VPN标识时，从所述转发表中查找到所述转发信息；之后，再为所述报文封装BIER头并进行转发。
  12. 如权利要求8-11中任一所述的位转发入口路由器，其中：
    所述报文转发模块为所述报文封装BIER头时，将所述BIER头中的报文类型设置为扩展的报文类型，所述扩展的报文类型用于指示报文中携带组播VRF的全局VPN标识。
  13. 一种组播虚拟专用网络VPN的承载方法，包括：
    接入组播虚拟专用网络路由转发VRF的位转发出口路由器BFER为所述组播VRF分配全局VPN标识，并记录具有所述全局VPN标识的报文的转发信息；
    所述BFER收到具有所述全局VPN标识的报文后，移除所述报文的BIER头，查找所述转发信息并进行报文转发。
  14. 如权利要求13所述的方法，其中：
    所述BFER记录具有所述全局VPN标识的报文的转发信息，包括：所述BFER创建所述组播VRF的实例，在所述实例对应的组播VRF路由表的路由中，记录具有所述全局VPN标识的报文的转发信息；
    所述BFER查找所述转发信息并进行报文转发，包括：所述BFER确定所述BIER头中的报文类型为扩展的报文类型时，将所述BIER头后的全局VPN标识移除，将剩下的载荷在所述组播VRF路由表中查表转发，所述扩展的报文类型用于指示报文中携带组播VRF的全局VPN标识。
  15. 如权利要求13所述的方法，其中：
    所述BFER记录具有所述全局VPN标识的报文的转发信息，包括：所述BFER在转发表中建立以所述全局VPN标识为键值的表项，在所述表项中记录带有所述全局VPN标识的报文的转发信息；
    所述BFER查找所述转发信息并进行报文转发，包括：所述BFER确定所述BIER头中的报文类型为扩展的报文类型时，根据所述BIER头后的所述全局VPN标识到所述转发表中查找所述转发信息并进行报文转发，所述扩展的报文类型用于指示报文中携带组播VRF的全局VPN标识。
  16. 如权利要求15所述的方法，其中：
    所述BFER进行报文转发，包括：所述BFER对所述报文进行二层封装时，将二层头中的协议类型设置为扩展的协议类型，所述扩展的协议类型用于指示二层头之后有一个全局VPN标识。
  17. 一种位转发出口路由器，包括：
    标识分配模块，设置为为本位转发入口路由器BFIR接入的组播虚拟专用网络路由转发VRF分配全局VPN标识；
    信息记录模块，设置为记录具有所述全局VPN标识的报文的转发信息；
    报文转发模块，设置为在收到具有所述全局VPN标识的报文后，移除所述报文的BIER头，查找所述转发信息并进行报文转发。
  18. 如权利要求17的位转发入口路由器，其中：
    所述信息记录模块记录具有所述全局VPN标识的报文的转发信息，包括：创建所述组播VRF的实例，在所述实例对应的组播VRF路由表的路由中，记录具有所述全局VPN标识的报文的转发信息；
    所述报文转发模块查找所述转发信息并进行报文转发，包括：确定所述BIER头中的报文类型为扩展的报文类型时，将所述BIER头后的全局VPN标识移除，将剩下的载荷在所述组播VRF路由表中查表转发，所述扩展的报文类型用于指示报文中携带组播VRF的全局VPN标识。
  19. 如权利要求17的位转发入口路由器，其中：
    所述信息记录模块记录具有所述全局VPN标识的报文的转发信息，包括：在转发表中建立以所述全局VPN标识为键值的表项，在所述表项中记录带有所述全局VPN标识的报文的转发信息；
    所述报文转发模块查找所述转发信息并进行报文转发，包括：确定所述BIER头中的报文类型为扩展的报文类型时，根据所述BIER头后的所述全局VPN标识到所述转发表中查找所述转发信息并进行报文转发，所述扩展的报文类型用于指示报文中携带组播VRF的全局VPN标识。
  20. 如权利要求19的位转发入口路由器，其中：
    所述报文转发模块进行报文转发，包括：对所述报文进行二层封装时，将二层头中的协议类型设置为扩展的协议类型，所述扩展的协议类型用于指示二层头之后有一个全局VPN标识。
  21. 一种位转发入口路由器，包括存储器、处理器及存储在所述存储器上并可在所述处理器上运行的计算机程序，所述处理器执行所述计算机程序时实现如权利要求1-7中任一所述的方法的处理。
  22. 一种位转发出口路由器，包括存储器、处理器及存储在所述存储器上并可在所述处理器上运行的计算机程序，所述处理器执行所述计算机程序时实现如权利要求13-16中任一所述的方法的处理。
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