CN101827012A - Packet transmitting network as well as method for bearing services of pure three layers of IP packets and outlet node - Google Patents

Abstract

The invention discloses a method for carrying a pure three-layer IP packet service on a packet transport network, the method comprising: identifying the IP address of the pure three-layer IP packet by an egress node of the packet transport network; the egress node pairs the identified IP address, matching the egress port; wherein, the corresponding relationship between the egress port and the IP address of the downstream device has been pre-configured in the egress node; the egress node forwards the pure layer-3 IP packet through the matched egress port. The invention also discloses a packet transmission network bearing pure three-layer IP packet service and its egress node. Adopting the present invention can realize the carrying of pure three-layer IP packets by the packet transmission network technology that does not support three-layer processing.

Description

Packet transport network and its method for carrying pure three-layer IP packet service, and egress node

technical field

The invention relates to the technical field of communication, in particular to a packet transport network and its method for carrying pure three-layer IP packet services, and an egress node.

Background technique

The existing pure three-layer (L3) IP (Internet Protocol, Internet Protocol) packet service mainly adopts IP/MPLS (Multiprotocol Label Switching, Multi-protocol Label Switching) technology based on three-layer forwarding, through IP IGP (Interior Gateway Protocol, Internal gateway protocol) routing protocol exchange IP routing information, each hop in the IP/MPLS network will decapsulate and encapsulate L2 information again, and directly forward according to the L3IP address information of the message. Figure 1 shows the operation of IP/MPLS technology carrying and forwarding pure layer 3 IP packet services.

PTN (Packet Transport Network, packet transport network) is a multi-service transport network adapted to IP-based packet services, with bandwidth statistical multiplexing and QoS (Quality of Service, quality of service) guarantee, and OAM (Operation Administration and Maintenance, operation, management and maintenance) and protection capabilities, are to support packet features such as multi-level QoS, flexibility and scalability, label forwarding and statistical multiplexing, and end-to-end OAM, reliability, synchronization timing and network management, etc. A network with connection-oriented networking characteristics of transport characteristics.

The packet transport network is based on layer-2 forwarding (only handles layer-2 services, not layer-3 services), and can identify layer-3 IP packets, and IP packets can be used as payloads to realize transparent transmission in the tunnel established by the packet transport network. The packet transport network is used to carry the pure layer 3 IP packet service. For the pure layer 3 IP packet service from the UNI (User Network Interface) side or the NNI (Network-Network Interface, network-network interface) side, first in the packet The carrier network label (i.e. the outer label) is encapsulated at the ingress node of the transport network, then a label switching path is established inside the packet transport network and the service is forwarded through the outer label, and finally the outer label is stripped at the egress node of the packet transport network. At the egress node of the packet transport network, since the pure L3IP packet service (non-L3VPN (Virtual Private Network, virtual private network) service) is addressed according to the IP routing protocol, if the egress node has multiple ports and one or more downstream devices If they are connected, the egress node of the packet transport network must be able to handle layer-3 services (support IP IGP routing function and realize layer-3 forwarding), that is, adopt IP/MPLS technology. Taking the packet transport network technology based on MPLS-TP (Multi Protocol Label Switching-Transport Profile, Multi Protocol Label Switching-Transport) as an example, the illustration of its carrying pure three-layer IP packet service is shown in Figure 2.

Using IP/MPLS technology based on layer 3 processing to carry pure layer 3 IP packet services has higher power consumption (about an order of magnitude higher under the same capacity) and higher failure rate than using packet transport network based on layer 2 processing to carry services (Under the same capacity, about 5 to 8 times higher) disadvantages. In addition, the use of IP/MPLS technology can handle pure three-layer IP packet services, while the use of packet transport network technology only handles two-layer services. Therefore, relatively speaking, the complexity of implementing IP/MPLS equipment is much greater than that of packet transport networks.

In some application situations, as long as the network can transparently transmit and identify pure layer-3 IP packets without implementing layer-3 processing (such as IP routing), it is a better choice to use packet transport network technology. For example, in a metropolitan area network, it is only necessary to process pure layer-3 IP packets at the service control sub-layer at the core layer, but not at the convergence and access layers.

The disadvantage of the existing technology is: at present, the solution of using packet transport network technology to carry pure three-layer IP packet service, when the egress node corresponds to multiple routers or other devices that support three-layer processing, if IP/MPLS technology is not supported , routing and forwarding cannot be performed.

Contents of the invention

An embodiment of the present invention provides a method for carrying a pure layer-3 IP packet service on a packet transport network, so as to realize a solution for carrying a pure layer-3 IP packet through a packet transport network technology that does not support layer-3 processing. The method includes:

The egress node of the packet transmission network identifies the IP address of the pure layer 3 IP packet;

The egress node matches the identified IP address with an egress port; wherein, the correspondence between the egress port and the IP address of the downstream device has been pre-configured in the egress node;

The egress node forwards the pure layer-3 IP packet through the matching egress port.

The embodiment of the present invention also provides an egress node of a packet transport network that carries pure three-layer IP packet services, so as to realize a solution for carrying pure three-layer IP packets by a packet transport network technology that does not support three-layer processing. The egress node includes:

Identification module, used to identify the IP address of the pure three-layer IP packet;

A matching module, configured to match an outgoing port to the identified IP address; wherein, the correspondence between the outgoing port and the IP address of the downstream device has been pre-configured at the exit node;

The forwarding module is configured to forward the pure layer-3 IP packet through the matched egress port.

The embodiment of the present invention also provides a packet transport network carrying pure three-layer IP packet services, which is used to realize the solution of carrying pure three-layer IP packets by packet transport network technology that does not support three-layer processing. The packet transport network includes:

An ingress node, located at the ingress of the packet transmission network, is used to receive and forward pure three-layer IP packets;

An internal node, located inside the packet transmission network, is used to receive and forward pure three-layer IP packets;

The egress node, located at the egress of the packet transport network, is used to identify the IP address of the pure three-layer IP packet; for the identified IP address, match the egress port; wherein, the correspondence between the egress port and the IP address of the downstream device has been described in the The egress node is pre-configured; the pure layer-3 IP packet is forwarded through the matching egress port.

In the embodiment of the present invention, the egress node of the packet transmission network identifies the IP address of the pure three-layer IP packet; the egress node matches the identified IP address to the outgoing port; wherein, the corresponding relationship between the outgoing port and the IP address of the downstream device has been Preconfigured at the egress node; the egress node forwards the pure layer-3 IP packet through the matching egress port, so that the egress node of the packet transmission network does not need to support the IP/MPLS routing function, and only needs to process the layer-2 information It can realize the bearer of pure three-layer IP packet service, which can reduce the implementation complexity of equipment; and, compared with the IP/MPLS technology based on three-layer forwarding, the embodiment of the present invention uses the packet transport network based on two-layer forwarding to carry pure three-layer Layer IP packet service, low power consumption and low failure rate.

Description of drawings

Fig. 1 is the operation schematic diagram of carrying and forwarding pure three-layer IP packet service in IP/MPLS technology in the background technology;

Fig. 2 is the schematic diagram of pure three-layer IP packet service carried by the packet transport network based on MPLS-TP in the background technology;

Fig. 3 is the flow chart of the method for carrying pure three-layer Ip packet service in the packet transport network in the embodiment of the present invention;

Fig. 4 is the schematic diagram of a specific example of adopting MPLS-TP-based packet transport network to carry the pure three-layer IP packet service from UNI interface in the embodiment of the present invention;

FIG. 5 is a schematic diagram of a specific example of using an MPLS-TP-based packet transport network to carry a pure three-layer IP packet service from an NNI interface in an embodiment of the present invention;

6 is a schematic diagram of a specific example of using a PBT-based packet transport network to carry a pure three-layer IP packet service from a UNI interface in an embodiment of the present invention;

7 is a schematic diagram of a specific example of using a PBT-based packet transport network to carry a pure three-layer IP packet service from an NNI interface in an embodiment of the present invention;

FIG. 8 is a schematic structural diagram of an egress node of a packet transport network carrying a pure three-layer IP packet service in an embodiment of the present invention;

FIG. 9 is a schematic structural diagram of a packet transport network carrying pure three-layer IP packet services in an embodiment of the present invention.

Detailed ways

Embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

As shown in Figure 3, in the embodiment of the present invention, the method flow of the packet transport network carrying pure three-layer IP packet service may include:

Step 301, the egress node of the packet transmission network identifies the IP address of the pure layer-3 IP packet.

Step 302, the egress node matches the identified IP address with an egress port; wherein, the correspondence between the egress port and the IP address of the downstream device has been pre-configured in the egress node.

Step 303, the egress node forwards the pure layer-3 IP packet through the matched egress port.

As can be seen from the process shown in Figure 3, in the embodiment of the present invention, at the egress node of the packet transport network that does not support IP/MPLS technology, the egress port is associated with the IP address of the downstream device through pre-static configuration, and the egress node identifies the three The IP address of the layer IP packet is matched to the outgoing port for forwarding. The downstream device of the packet transport network may be a peer router of the UNI interface, a peer router of the NNI interface, or other devices supporting layer-3 processing.

Packet transport network technology includes two known mainstream technologies: MPLS-TP technology, PBT (Provider Backbone Transport, operator backbone transport) technology, and other technologies with packet transport network characteristics. The following are MPLS-TP technology , PBT technology as an example, describe the specific implementation of the solution of the present invention in detail.

MPLS-TP originates from the layer-1 transmission technology and the layer-3 IP/MPLS technology, and enhances the carrying capacity of transmission equipment for data packet services by introducing MPLS label technology. The packet transport network technology using MPLS-TP is logically divided into three layers: PW (Pseudowire, pseudowire) layer, LSP (Label Switched Path, label switched path) layer and section layer (Section). At the pseudowire layer, encapsulate the PW label and use PW technology to realize multi-service bearer such as L2 Ethernet and IP/MPLS, and ensure the transparency of the user layer; at the LSP layer, encapsulate the LSP label and implement forwarding based on Layer 2; at the segment layer It can be transmitted by various physical layer media such as Ethernet. If the Ethernet physical layer is used, the second layer MAC (Media Access Control, Media Access Control) needs to be encapsulated.

When the packet transport network based on MPLS-TP is used to carry the pure layer 3 IP packet service from the UNI interface, before the egress node identifies the IP address of the pure layer 3 IP packet, it may also include: For the pure layer 3 IP packet service from the UNI interface The ingress node of the packet transport network encapsulates the PW label and the LSP label; the internal node of the packet transport network establishes a label switching path LSP, and uses the LSP label to perform layer-2 forwarding.

A specific example of using MPLS-TP-based packet transport network to carry the pure three-layer IP packet service from the UNI interface is shown in Figure 4. In this example, CE1 (Customer Equipment, user terminal) and CE2 are located at the user (User Equipment) of the UNI interface. User) side, PTN1 and PTN3 are located on the Network side of the UNI interface. For the pure layer 3 IP packet service from CE1, the PW label and LSP label are first encapsulated at the ingress node PTN1 of the packet transport network (at this time, the physical layer MAC address L2 on the UNI side can be reserved or stripped). Establish a label switched path (LSP) inside the packet transport network (PTN1->PTN2->PTN3), and use the LSP label to implement forwarding based on the second layer. If the physical layer uses Ethernet media, each hop in the packet transport network It is also necessary to encapsulate the MAC address (such as L21 and L22) at the outermost of the pure three-layer IP packet. Finally, at the egress node PTN3 of the packet transport network, the IP address of the layer-3 IP packet is identified to match the outgoing port to achieve forwarding. The premise is that the outgoing port of PTN3 corresponds to the IP address of the peer CE2 device of the UNI through pre-static configuration. .

When the packet transport network based on MPLS-TP is used to carry the pure layer 3 IP packet service from the NNI interface, before the egress node identifies the IP address of the pure layer 3 IP packet, it may also include: For the pure layer 3 IP packet service from the NNI interface , the internal nodes of the IP/MPLS network perform three-layer forwarding according to the routing and forwarding mechanism of IP/MPLS; the ingress nodes of the packet transport network encapsulate PW labels and LSP labels; the internal nodes of the packet transport network establish label switching paths LSP , and LSP labels are used for Layer 2 forwarding.

A specific example of using an MPLS-TP-based packet transport network to carry pure three-layer IP packet services from the NNI interface is shown in Figure 5. In this example, P2 and P3 are located on the IP/MPLS network side of the NNI interface, and PTN1 and PTN3 Located on the MPLS-TP-based PTN network side of the NNI interface. For the pure layer 3 IP packet service from CE1, within the IP/MPLS network, follow the IP/MPLS routing and forwarding mechanism to implement layer 3 forwarding. The PW label and the LSP label are encapsulated at the ingress node PTN1 of the packet transport network (at this time, the physical layer MAC address L23 on the NNI side can be reserved or stripped). Establish a label switched path (LSP) inside the packet transport network (PTN1->PTN2->PTN3), and use the LSP label to implement forwarding based on the second layer. If the physical layer uses Ethernet media, each hop in the packet transport network It is also necessary to encapsulate the MAC address (such as L24 and L25) at the outermost of the pure three-layer IP packet. Finally, at the egress node PTN3 of the packet transport network, the IP address of the layer-3 IP packet is identified to match the outgoing port for forwarding. The premise is that the outgoing port of PTN3 corresponds to the IP address of the peer P3 device of the NNI through pre-static configuration. .

PBT is derived from Layer 2 Ethernet technology, removes the connectionless feature of Ethernet, and strengthens carrier-class capabilities such as OAM and protection of Ethernet devices. Using PBT packet transport network technology, if the physical layer is an Ethernet medium, it is logically divided into two layers: the inner layer (encapsulating the MAC address of the user layer) and the outer layer (ie the tunnel layer, encapsulating the MAC address of the operator layer). The inner layer naturally supports Ethernet services, and can also use Pseudowire (PW) technology to carry other services (such as IP/MPLS services) and ensure the transparency of the user layer. In the outer layer, the forwarding based on the second layer is realized through the carrier layer MAC address and VLAN (Virtual Local Area Network, virtual local area network) ID (identification).

When the PBT-based packet transport network is used to bear the pure layer 3 IP packet service from the UNI interface, before the egress node identifies the IP address of the pure layer 3 IP packet, it may also include: for the pure layer 3 IP packet service from the UNI interface The ingress node of the packet transport network encapsulates the inner layer information and the outer layer information; the internal node of the packet transport network establishes a label switching path, and uses the layer 2 information to perform layer 2 forwarding. The inner layer information may include a user layer MAC address; and/or the outer layer information may include an operator MAC address.

A specific example of using a PBT-based packet transport network to carry pure three-layer IP packet services from the UNI interface is shown in Figure 6. In this example, CE1 and CE2 are located on the user (User) side of the UNI interface, and PTN1 and PTN3 are located on the UNI interface. The Network side of the interface. For the pure three-layer IP packet service from CE1, the inner layer information such as the user layer MAC address and the outer layer information such as the operator MAC address are first encapsulated at the ingress node PTN1 of the packet transport network. Establish a label switching path inside the packet transport network (PTN1->PTN2->PTN3), and use L2 information such as the outer layer MAC address to implement layer-2 forwarding. Finally, at the egress node PTN3 of the packet transport network, the IP address of the layer-3 IP packet is identified to match the outgoing port to achieve forwarding. The premise is that the outgoing port of PTN3 corresponds to the IP address of the peer CE2 device of the UNI through pre-static configuration. .

When the PBT-based packet transport network is used to carry the pure layer 3 IP packet service from the NNI interface, before the egress node identifies the IP address of the pure layer 3 IP packet, it may also include: for the pure layer 3 IP packet service from the NNI interface, The internal nodes of the IP/MPLS network perform three-layer forwarding according to the routing and forwarding mechanism of IP/MPLS; the entry nodes of the packet transport network encapsulate inner layer information and outer layer information; the internal nodes of the packet transport network establish label switching paths , and uses Layer 2 information for Layer 2 forwarding. The inner layer information may include a user layer MAC address; and/or the outer layer information may include an operator MAC address.

A specific example of using a PBT-based packet transport network to carry pure three-layer IP packet services from the NNI interface is shown in Figure 7. In this example, P2 and P3 are located at the IP/MPLS network side of the NNI interface, and PTN1 and PTN3 are located at the NNI PBT-based PTN network side of the interface. For the pure layer 3 IP packet service from CE1, within the IP/MPLS network, follow the IP/MPLS routing and forwarding mechanism to implement layer 3 forwarding. The inner layer information such as the user layer MAC address and the outer layer information such as the operator MAC address are encapsulated at the ingress node PTN1 of the packet transport network. Establish a label switching path inside the packet transport network (PTN1->PTN2->PTN3), and use L2 information such as the outer layer MAC address to implement layer-2 forwarding. Finally, at the egress node PTN3 of the packet transport network, the IP address of the layer-3 IP packet is identified to match the outgoing port for forwarding. The premise is that the outgoing port of PTN3 corresponds to the IP address of the peer P3 device of the NNI through pre-static configuration. .

Those skilled in the art can understand that all or part of the steps in the methods of the above embodiments can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium, and the storage medium can include: ROM, RAM, Disk or CD etc.

Based on the same inventive concept, an embodiment of the present invention also provides an egress node of a packet transport network that carries pure three-layer IP packet services. Its structure is shown in FIG. 8 and may include:

Identification module 801, used to identify the IP address of the pure three-layer IP packet;

The matching module 802 is used to match the identified IP address with the outgoing port; wherein, the corresponding relationship between the outgoing port and the IP address of the downstream device has been pre-configured at the exit node;

The forwarding module 803 is configured to forward the pure layer-3 IP packet through the matched egress port.

Based on the same inventive concept, the embodiment of the present invention also provides a packet transport network carrying pure three-layer IP packet services, the structure of which is shown in Figure 9, which may include:

An ingress node 901, located at the ingress of the packet transport network, is used to receive and forward pure layer 3 IP packets;

Internal node 902, located inside the packet transport network, for receiving and forwarding pure layer 3 IP packets;

Egress node 903, located at the egress of the packet transmission network, is used to identify the IP address of the pure three-layer IP packet; for the identified IP address, match the egress port; wherein, the corresponding relationship between the egress port and the IP address of the downstream device is already in the The egress node is pre-configured; the pure layer-3 IP packet is forwarded through the matching egress port.

In one embodiment, the ingress node 901 can also be used to identify the identity of the pure layer 3 IP packet at the egress node when the packet transport network is based on MPLS-TP and carries the pure layer 3 IP packet service from the UNI or NNI interface. Before the IP address, the PW label and the LSP label are encapsulated; the internal node 902 can also be used to establish a label switching path LSP, and use the LSP label to perform layer-2 forwarding.

In one embodiment, the ingress node 901 can also be used to identify the IP address of the pure layer 3 IP packet at the egress node when the packet transport network is based on PBT and carries the pure layer 3 IP packet service from the UNI or NNI interface Before, the inner layer information and the outer layer information are encapsulated; the inner node 902 can also be used to establish a label switching path, and use the layer 2 information to perform layer 2 based forwarding.

In the embodiment of the present invention, the egress node of the packet transmission network identifies the IP address of the pure three-layer IP packet; the egress node matches the identified IP address to the outgoing port; wherein, the corresponding relationship between the outgoing port and the IP address of the downstream device has been Pre-configured at the egress node; the egress node forwards the pure layer-3 IP packet through the matching egress port, so that the egress node of the packet transport network does not need to support IP/MPLS routing functions, and only needs to process layer-2 information ( No need to forward and process three-layer information) can realize the bearing of pure three-layer IP packet service, which can reduce the implementation complexity of equipment; and, compared with the IP/MPLS technology based on three-layer forwarding, the embodiment of the present invention uses Layer-forwarded packet transport network carries pure three-layer IP packet services, with low power consumption (tested or verified on the live network, under the same capacity, about an order of magnitude lower), and low failure rate (tested or verified on the live network, in Under the same capacity, it is about 5-8 times lower).

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and equivalent technologies, the present invention also intends to include these modifications and variations.

Claims (12)

1. a Packet Transport Network carries the method for pure three-layer network border protocol IP bag business, it is characterized in that this method comprises:

The IP address of the Egress node identification pure three layers of IP bag of Packet Transport Network;

The IP address of described Egress node to identifying matches port; Wherein, the corresponding relation of outbound port and upstream device IP address is pre-configured at described Egress node;

Described Egress node is transmitted described pure three layers of IP bag by the outbound port of coupling.

2. the method for claim 1, it is characterized in that, described Packet Transport Network based on multi protocol label exchange-transmission aspect MPLS-TP carrying from the pure three layers of IP bag of User Network Interface uni interface when professional, before the IP address of described Egress node identification pure three layers of IP bag, further comprise:

For the pure three layers of IP bag business from uni interface, the Ingress node of described Packet Transport Network encapsulates pseudo-line PW label and label switching path LSP label;

The internal node of described Packet Transport Network is set up label switching path LSP, and employing LSP label carries out the forwarding based on two layers.

3. the method for claim 1 is characterized in that, described Packet Transport Network when professional, before the IP address of described Egress node identification pure three layers of IP bag, further comprises from the pure three layers of IP bag of Network-Network interface NNI interface based on MPLS-TP carrying:

For the pure three layers of IP bag business from the NNI interface, the internal node of IP/MPLS network carries out three layers of forwarding by route and the forwarding mechanism of IP/MPLS;

The Ingress node encapsulation PW label and the LSP label of described Packet Transport Network;

The internal node of described Packet Transport Network is set up label switching path LSP, and employing LSP label carries out the forwarding based on two layers.

4. as claim 2 or 3 described methods, it is characterized in that,, then jump, in the outermost packaged media access control MAC address of described pure three layers of IP bag in each of described Packet Transport Network inside if physical layer adopts the Ethernet media.

5. the method for claim 1 is characterized in that, described Packet Transport Network transmits the PBT carrying based on operator backbone and, before the IP address of described Egress node identification pure three layers of IP bag, further comprises when professional from the pure three layers of IP bag of uni interface:

For the pure three layers of IP bag business from uni interface, the Ingress node encapsulate inner layer information of described Packet Transport Network and outer information;

The internal node of described Packet Transport Network is set up label switched path, and adopts two layers of information to carry out forwarding based on two layers.

6. the method for claim 1 is characterized in that, described Packet Transport Network when professional, before the IP address of described Egress node identification pure three layers of IP bag, further comprises from the pure three layers of IP bag of NNI interface based on PBT carrying:

For the pure three layers of IP bag business from the NNI interface, the internal node of IP/MPLS network carries out three layers of forwarding by route and the forwarding mechanism of IP/MPLS;

The Ingress node encapsulate inner layer information of described Packet Transport Network and outer information;

The internal node of described Packet Transport Network is set up label switched path, and adopts two layers of information to carry out forwarding based on two layers.

7. as claim 5 or 6 described methods, it is characterized in that described internal layer information comprises the client layer MAC Address; And/or described outer information comprises operator's MAC Address.

8. the method for claim 1 is characterized in that, described upstream device comprises: the end-to-end router of the end-to-end router of uni interface, NNI interface or other are supported the equipment of three layers of processing.

9. an Egress node that carries the Packet Transport Network of pure three layers of IP bag business is characterized in that, comprising:

Identification module is used to discern the IP address of pure three layers of IP bag;

Matching module is used for the IP address to identifying, and matches port; Wherein, the corresponding relation of outbound port and upstream device IP address is pre-configured at described Egress node;

Forwarding module is used for the outbound port by coupling, transmits described pure three layers of IP bag.

10. a Packet Transport Network that carries pure three layers of IP bag business is characterized in that, comprising:

Ingress node is positioned at described Packet Transport Network inlet, is used for receiving and transmitting the pure three layers of IP bag;

Internal node is positioned at described Packet Transport Network inside, is used for receiving and transmitting the pure three layers of IP bag;

Egress node is positioned at described Packet Transport Network outlet, is used to discern the IP address of pure three layers of IP bag; IP address to identifying matches port; Wherein, the corresponding relation of outbound port and upstream device IP address is pre-configured at described Egress node; By the outbound port of coupling, transmit described pure three layers of IP bag.

11. Packet Transport Network as claimed in claim 10, it is characterized in that, described Ingress node be further used for described Packet Transport Network based on MPLS-TP, carrying from the pure three layers of IP bag of UNI or NNI interface when professional, before the IP address of described Egress node identification pure three layers of IP bag, encapsulation PW label and LSP label;

Described internal node is further used for setting up label switching path LSP, and employing LSP label carries out the forwarding based on two layers.

12. Packet Transport Network as claimed in claim 10, it is characterized in that, described Ingress node be further used for described Packet Transport Network based on PBT, carrying from the pure three layers of IP bag of UNI or NNI interface when professional, before the IP address of described Egress node identification pure three layers of IP bag, encapsulation encapsulate inner layer information and outer information;

Described internal node is further used for setting up label switched path, and adopts two layers of information to carry out forwarding based on two layers.

Images