Patent Description:
The present disclosure relates to the communication field, and the invention in particular relates to packet processing methods and apparatuses.

Segment routing (segment routing, SR) is a source routing technology. A head node of an SR tunnel specifies a path for a packet, and converts the path into an ordered segment list to encapsulate the ordered segment list into a packet header. An intermediate node on the path needs to perform forwarding only based on the specified path in the packet header. The head node of the SR tunnel is the <NUM>st node encountered after the packet enters the SR tunnel. When the SR is deployed on an Internet Protocol version <NUM> (Internet Protocol version <NUM>, IPv6) data plane, the SR is referred to as segment routing over IPv6 (Segment Routing over IPv6, SRv6 for short). To support a segment routing protocol in IPv6, an extension header, namely, a segment routing header (Segment Routing Header, SRH), is added after a basic IPv6 header, to obtain an SRv6 data packet. The SRH extension header carries an SL (segment list). Each segment is identified by using a <NUM>-bit IPv6 address, and packet forwarding depends on information encoded by using an IPv6 address. In an IPv6 router, a segment list can be represented only by using a segment identifier (Segment Identifier, SID) that is in a form of an IPv6 address. Otherwise, forwarding cannot be performed. Therefore, the SL in the SRH is an explicit segment identifier (SID) stack. An intermediate node continuously updates a destination address and offsets the segment identifier stack, to complete hop-by-hop forwarding. The SRv6 controls, on the head node of the SR tunnel, a forwarding path based on the foregoing processing.

However, a forwarding plane of the SRv6 is IPv6. If there is a non-IPv6 network (for example, a network that supports only IPv4 forwarding), an SRv6 packet needs to traverse the network by using another technology. In an existing related technology, a path selection policy is independently configured on an edge node connected to both the non-IPv6 network and the IPv6 network, to traverse the non-IPv6 network. A plurality of paths may exist on a same edge node. When receiving an IPv6 packet on an edge node, the edge node selects, based on the configured path selection policy, a path to traverse an IPv4 network.

In the existing related technology, because the independent path selection policy further needs to be deployed on the edge node when the packet traverses the non-IPv6 network, resources are wasted, and the head node of the SR tunnel cannot control an end-to-end forwarding path.

<CIT> relates to techniques for providing control plane messaging in an active-active (or all-active) configuration of a multi-homed EVPN environment. In some examples, the techniques include receiving a control plane message comprising at least one address that identifies that second PE network device. The techniques may include configuring, based at least in part on the control plane message, a forwarding plane of a first PE network device to identify network packets having respective destination addresses that match the at least one address. The techniques may include determining that at least one address of the network packet matches the at least one address that identifies the second PE network device. The techniques may also include, responsive to the determination, skipping a decrement of the Time-To-Live (TTL) value of the network packet, and forwarding the network packet to the second PE network device.

The object of the present invention is to provide packet processing methods and apparatuses to implement end-to-end transmission control on an IPv6 packet. This object is solved by the attached independent claims and further embodiments and improvements of the invention are listed in the attached dependent claims. Hereinafter, up to the "brief description of the drawings", expressions like ". aspect according to the invention", "according to the invention", or "the present invention", relate to technical teaching of the broadest embodiment as claimed with the independent claims. Expressions like "implementation", "design", "optionally", "preferably", "scenario", "aspect" or similar relate to further embodiments as claimed, and expressions like "example", ". aspect according to an example", "the disclosure describes", or "the disclosure" describe technical teaching which relates to the understanding of the invention or its embodiments, which, however, is not claimed as such.

The following describes the present invention in detail with reference to the accompanying drawings and specific embodiments. However, it should be noted that the following embodiments are only examples for ease of understanding of the technical solutions, but are not intended to limit the present invention.

The embodiments of this application are mainly applied to a scenario in which a packet is transmitted by using a traversal technology. Generally, when a second network different from a first network exists in the first network for packet transmission, the traversal technology needs to be used to traverse the second network, to complete packet transmission. In the embodiments of this application, when the network needs to be traversed, a node in the first network determines a packet transmission path, where the packet transmission path includes a transmission path in the first network and a path traversing the second network. The node in the first network in the embodiments of this application is a head node of an SR tunnel established in the first network. The node in the first network adds end-to-end path information to a packet based on the determined path. The path information includes traversal indication information, used to indicate an ingress node and an egress node of the packet in the second network. After receiving the packet, the ingress node in the second network encapsulates the packet based on the traversal indication information in the packet, to change a format of the packet to a format supported by the second network, and routes the encapsulated packet to the specified egress node, to complete traversal. In this way, the node in the first network selects a tunnel exit in the second network, and the ingress node in the second network is indicated by the traversal indication information to perform routing based on the specified egress node, so that independent deployment of a routing policy on the ingress node in the second network is avoided. This reduces resource overheads. In addition, the node in the first network further controls the end-to-end forwarding path.

In a specific embodiment, the node in the first network may not only indicate the ingress node and the egress node in the second network by using the traversal indication information, but also indicate, by using the traversal indication information, a tunnel encapsulation type that needs to be used. After receiving the packet, the ingress node in the second network encapsulates the packet based on the tunnel encapsulation type specified in the traversal indication information. The node in the first network may further copy information from the packet before encapsulation to a packet after encapsulation by using the traversal indication information. Specifically, the node in the first network may indicate, in the traversal indication information, the information that needs to be copied. When encapsulating the packet, the ingress node in the second network copies the information that is specified in the traversal indication information and that needs to be copied.

An implementation process of the embodiments of this application is described in detail below by using an example in which an IPv4 network that needs to be traversed exists in an IPv6 network.

In the implementation process of the embodiments of this application, packet changing is involved. Therefore, for ease of understanding, a format of a packet transmitted in the IPv6 network is first described briefly.

The packet transmitted in the IPv6 network is an IPv6 packet that uses an IPv6 protocol or an SRv6 packet obtained through extension of an IPv6 packet. The solution provided in the embodiments of this application may be implemented based on the SRv6 packet. The IPv6 packet includes a standard IPv6 header, an extension header (<NUM>. n), and a payload. To implement SRv6 based on an IPv6 forwarding plane, an IPv6 extension header, which is referred to as a segment routing header (Segment Routing Header, SRH), is newly added. The extension header specifies an explicit IPv6 path, and stores information about an IPv6 segment list (Segment List). A head node of an SRv6 tunnel adds an SRH extension header to an IPv6 packet (to obtain the SRv6 packet), and an intermediate node can perform forwarding based on path information included in the SRH extension header. <FIG> shows a format of an SRH extension header according to an embodiment of this application.

Each field in the SRH extension header shown in <FIG> is explained as follows:
Next Header field: A length of the Next Header field is <NUM> bits, and the Next Header field is used to identify a type of a packet header following the SRH.

Hdr Ext Len field: A length of the Hdr Ext Len field is <NUM> bits, and the Hdr Ext Len field is used to indicate a length of the SRH extension header, which is a length from a segment list [<NUM>] to a segment list [n].

Routing Type field: A length of the Routing Type field is <NUM> bits, and the Routing Type field is used to identify a type of a routing header, where an SRH type is <NUM>.

Segments Left field: A length of the Segments Left field is <NUM> bits, and the Segments Left field is used to indicate a quantity of intermediate nodes that still need to be accessed before a destination node is reached.

Last Entry field: A length of the Last Entry field is <NUM> bits, and the Last Entry field is used to indicate an index of the last element in a segment list.

Flags field: A length of the Flags field is <NUM> bits, and the Flags field indicates some identifiers of data packets.

Tag field: A length of the Tag field is <NUM> bits, and the Tag field identifies data packets in a same group.

Segment List [n] field: A length of the Segment List [n] field is <NUM>*n bits, this field forms a segment list, and the segment list is encoded from the last segment of a path. The segment list is in a form of an IPv6 address.

For ease of describing a forwarding principle, the SRH extension header shown in <FIG> may be abstracted into a form shown in <FIG>.

Each field in <FIG> is described as follows: IPv6 Destination Address field: The IPv6 Destination Address field indicates a destination address of an IPv6 packet, and is referred to as an IPv6 DA for short. In a common IPv6 packet, an IPv6 DA is fixed. In an SRv6 packet, an IPv6 DA identifies only a next node of the current packet, and is changeable.

<Segment List [<NUM>], Segment List [<NUM>], Segment List [<NUM>],. , Segment List [n]> field: The <Segment List [<NUM>], Segment List [<NUM>], Segment List [<NUM>],. , Segment List [n]> field indicates segment lists of an SRv6 packet, where the segment lists are generated on an ingress node. A segment list [<NUM>] is the <NUM>st SRv6 segment that needs to be processed on an SRv6 path, a segment list [<NUM>] is the <NUM>nd, a segment list [<NUM>] is the <NUM>rd,. , and a segment list [n] is the (n+<NUM>)th.

As shown in <FIG>, each time when an SRv6 node is passed through, a Segments Left (SL) in an SRv6 packet is decreased by one, and IPv6 DA information is changed for one time. The IPv6 DA information is determined by the Segments Left field and a Segment List field together. If a value of the SL field is n (that is, n-<NUM>), a value of the IPv6 DA is a value of the segments list [<NUM>].

If a value of the SL field is n-<NUM>, a value of the IPv6 DA is a value of the segments list [<NUM>];
if a value of the SL field is n-<NUM>,
a value of the IPv6 DA is a value of the segments list [<NUM>];
if a value of the SL field is <NUM> (n-n=<NUM>),
a value of the IPv6 DA is a value of the segments list [n].

It should be noted that the field or the packet structure in the foregoing embodiments is merely intended to describe the SRv6 packet and a rule thereof. This application is not limited thereto. During specific practice, some specific-implementation-level changes that do not change a basic principle may be made based on different implementation scenarios.

The segment list in the segment list field is in a form of an IPv6 address, and generally, may also be referred to as an SID (Segment Identifier). <FIG> is a schematic diagram of a format of an SRv6 SID according to an embodiment of this application. The SID includes a Locator field (Locator) and a Function field (Function), and a corresponding format is Locator: Function. The Locator field occupies a high bit of an IPv6 address, and the Function part occupies a remaining part of the IPv6 address.

The Locator field has a locating function, and therefore needs to be unique in an SR domain. After a node configures the Locator field, a system generates a Locator network segment route, and propagates the Locator network segment route in the SR domain by using an IGP. Another node in the network may locate the node by using the Locator network segment route, and all SRv6 SIDs advertised by the node are reachable by using the Locator network segment route. The Function field represents an instruction (Instruction) of a device. The instruction may be preset by the device. The Function part is used to indicate a node that generates the SID to perform a corresponding function operation. An optional parameter segment field (Arguments) may further be separated from the Function part. In this case, the format of the SRv6 SID is changed to Locator: Function: Arguments. The Arguments field occupies a low bit of the IPv6 address, and can be used to define some information such as a packet flow and a service. Both the Function field and the Arguments field can be defined.

There are many types of SRv6 SIDs, and different types of SRv6 SIDs represent different functions.

An embodiment of this application proposes a new SRv6 SID function, that is, proposes a new SID type, to indicate behavior of a new network node. The new SID type defined in this embodiment of this application may be represented as: End. Encaps, where a full name of End. Encaps is that Endpoint encapsulates the original SRv6 packet into an IPv4 tunnel. During specific implementation, a new bit may be defined in a Function part of an SID to represent the new network behavior. The newly defined bit and a meaning represented by the bit may be advertised by a control plane to each node on a forwarding plane, so that the node on the forwarding plane can identify and use the new type of SID. The network behavior defined by the newly defined SID in this embodiment of this application is a network traversal behavior. Traversal indication information may be included, and is used to indicate a behavior of an edge node, corresponding to the SID, in an IPv4 network when an SRv6 packet traverses the IPv4 network and when the edge node receives the SRv6 packet. Specifically, the traversal indication information in the SID may indicate an egress node when the packet traverses the IPv4 network, and may further indicate a tunnel encapsulation type used when the packet traverses the IPv4 network, or indicate information that needs to be copied to the packet, encapsulated to change a format of the packet to an IPv4 format, when the packet traverses the IPv4 network.

The following describes in detail application of the new SID with reference to an application scenario. <FIG> is a schematic diagram of a scenario to which an embodiment of this application is applied. As shown in <FIG>, there are three segments of networks, namely, two segments of IPv6 networks and one segment of IPv4 network, in a network. The IPv6 network is a first network in this embodiment of this application, and the IPv4 network is a second network that needs to be traversed in this embodiment of this application. An SRv6 packet sent by R1 needs to pass through the intermediate IPv4 network and reach R7. Three network devices, namely, R3, R4, and R5, are edge nodes in the IPv4 network, and support IPv4/IPv6 dual stack. A tunnel exists both between R3 and R4 and between R3 and R5. When the SRv6 packet reaches R3, R4 or R5 may be selected as a tunnel exit.

In this embodiment of this application, when advertising an SID of the edge node, the edge node may use the SID newly defined in this embodiment of this application. For example, R3 in <FIG> may advertise two SIDs: an SID <NUM> and an SID <NUM>. A Function part of the SID <NUM> indicates that an egress node when the packet traverses the IPv4 network is R5. A Function part of the SID <NUM> indicates that an egress node when the packet traverses the IPv4 network is R4. During specific implementation, the edge node may further indicate, in the Function part of the SID, a tunnel encapsulation type used during traversal, content that needs to be copied to the encapsulated packet during traversal, or the like.

The following describes, by using the scenario shown in <FIG> as an example, a method in which an SRv6 packet traverses an IPv4 network according to an embodiment of this application. <FIG> is a flowchart of processing a packet by a head node of an SRv6 tunnel in an IPv6 network according to an embodiment of this application. As shown in <FIG>, a processing process of the head node includes the following steps.

S601: After receiving a packet, a head node in the IPv6 network determines an end-to-end path for transmitting the packet.

The IPv6 network is an SRv6 network in which SR is deployed. The head node in the IPv6 network is the head node of the SRv6 tunnel established in the IPv6 network, namely, the <NUM>st node (that is, an ingress node of the packet in the SRv6 network) encountered after the packet enters the SRv6 tunnel, for example, the node R1 in <FIG>.

After receiving the packet, the head node selects the end-to-end transmission path for the packet, where the end-to-end path includes a transmission path in the SRv6 network and a path traversing an IPv4 network. The path traversing the IPv4 network may be a tunnel by which an ingress node and an egress node in the IPv4 network are determined. Using <FIG> as an example, R1 may select R3 as the ingress node in the IPv4 network, and select R5 as the egress node in the IPv4 network.

It should be noted that the ingress node and the egress node in the IPv4 network are edge nodes connected to both the IPv4 network and the IPv6 network, and support IPv4/IPv6 dual stack.

S602: The head node in the IPv6 network adds path information to an extension header of the packet based on the end-to-end path. The path information includes traversal indication information, and the traversal indication information is used to indicate the ingress node and the egress node of the packet in the IPv4 network.

The path information may exist in a form of a segment list in an SRv6 packet format. Specifically, the head node may add the path information to an SRH extension header of the packet, and store, in a segment list in the SRH extension header, an SID of an intermediate node on the end-to-end path. An SID that is carried in the packet and that is of the ingress node in the IPv4 network may be an SID having a newly added function provided in this embodiment of this application. The traversal indication information is carried in the SID, and is used to specify behavior of the ingress node in the IPv4 network.

It should be noted that the ingress node in the IPv4 network may advertise a plurality of SIDs, and different SIDs carry different traversal indication information. For example, in <FIG>, R3 advertises an SID <NUM> and an SID <NUM>. Traversal indication information in the SID <NUM> indicates that an egress node when the packet traverses the IPv4 network is R5. Traversal indication information in the SID <NUM> indicates that an egress node when the packet traverses the IPv4 network is R4. When adding the end-to-end path information to the packet, the head node may use an SID corresponding to the path that is determined by the head node based on the traversal indication information and that traverses the second network as the SID of the ingress node in the IPv4 network, and adds the SID to the end-to-end path information. For example, in this embodiment, for the path that is determined by the head node and that traverses the IPv4 network, R3 is used as the ingress node in the IPv4 network, and R5 is used as the egress node in the IPv4 network. Therefore, the head node may select the SID <NUM> as the SID of the ingress node in the IPv4 network, and add the SID <NUM> to the path information.

In this embodiment, the traversal indication information may further indicate a tunnel type used when the packet traverses the IPv4 network. For example, the tunnel type is NVO3.

S603: The head node in the IPv6 network sends the packet to which the path information is added to a next node.

For example, the head node R1 in <FIG> sends, to an intermediate node R2, the packet to which the path information is added. After receiving the packet, the intermediate node R2 continues to send the packet to the next node R3 based on a node address in the segment list in the packet. Till this step, an existing processing process may be used, and details are not described herein again.

The foregoing process is the processing process performed by the head node for transmitting the packet. In this process, aside from having a capability of selecting the path in the IPv6 network (where the capability is implemented by using the SRv6 SRH), the head node in the IPv6 network further needs to have a capability of selecting a tunnel exit for traversing the IPv4 network. The ingress node in the IPv4 network is indicated by the traversal indication information to perform routing based on the specified egress node, so that independent deployment of a routing policy on the ingress node in the IPv4 network is avoided. This reduces resource overheads. In addition, the head node further controls the end-to-end forwarding path.

The following further describes the processing process performed by the ingress node in the IPv4 network. <FIG> is a flowchart of processing performed by an ingress node in an IPv4 network according to an embodiment of this application. The processing process includes the following steps.

S701: After receiving a packet from an IPv6 network, the ingress node in the IPv4 network updates a segment left (Segment Left, SL) field and an IPv6 destination address (IPv6 DA) field in the IPv6 packet.

After receiving the packet, if determining that a next packet header in the packet is an SRH, and that a value of the SL field is greater than zero, the ingress node performs the update operation. The update operation includes: subtracting the value of the SL field by one, and replacing an address in the IPv6 DA field by using an SRH [SL]. For the update process, refer to the descriptions in <FIG>.

It should be noted that if the value of the SL field is equal to <NUM>, it indicates that the packet has reached a destination node, and a packet transmission process ends. However, in this embodiment, the ingress node is not the destination node.

The scenario shown in <FIG> is still used as an example. When receiving the packet, the ingress node R3 modifies the value of the SL field to <NUM>, and modifies the address in the IPv6 DA field to an address corresponding to an SRH [<NUM>].

S702: The ingress node encapsulates the packet, to change a format of the packet to a format supported by the IPv4 network, sets, in an encapsulation process based on traversal indication information, a source address of the packet as an address corresponding to the ingress node, and sets a destination address of the packet as an address corresponding to an egress node in the traversal indication information.

Specifically, after updating the IPv6 packet, the ingress node encapsulates an IPv4 packet header at an outer layer of the IPv6 packet, so that the packet can be transmitted in the IPv4 network. In the encapsulation process, the ingress node sets, based on the traversal indication information in the SID, a source address of the IPv4 packet header as an IPv4 address of the ingress node or an IPv4 address of an interface corresponding to the ingress node, and sets a destination address of the IPv4 packet header as an IPv4 address of the egress node in the traversal indication information or an IPv4 address of an interface corresponding to the egress node.

When the packet traverses the IPv4 network, a tunnel technology may be used for traversal. Different tunnel technologies have different encapsulation manners. That is, different tunnel encapsulation types may be used when the packet is encapsulated. The tunnel encapsulation type may be specified in the traversal indication information. In this embodiment, the traversal indication information indicates that an NVO3 tunnel encapsulation type is used. When the Network Virtualization over Layer <NUM> (NVO3) tunnel encapsulation type is used, the IPv6 packet may traverse the IPv4 network through an overlay network, for example, a Layer <NUM> tenant network. An overlay tunnel is established between the ingress node and the egress node in the IPv4 network, and the IPv6 packet completes traversal by using the overlay tunnel. An encapsulation manner of the NVO3 tunnel encapsulation type may include a virtual extensible local area network (Virtual eXtensible Local Area Network, VXLAN), a generic protocol extension for a virtual extensible local area network (generic protocol extension for a virtual extensible local area network, VXLAN-GPE), generic network virtualization encapsulation (Generic Network Virtualization Encapsulation, GENEVE), or the like.

To implement NVO3 tunnel encapsulation, the ingress node may further encapsulate a UDP header at the outer layer of the packet, and set an overlay header and a UDP destination port that corresponds to an overlay protocol header. The process may specifically include the following steps.

Set a UDP port number, where a destination port number is a port number corresponding to the overlay header, for example, VXLAN (<NUM>), VXLAN-GPE (<NUM>), or GENEVE (<NUM>).

Fill a virtual network ID field based on an indication of the SID, for example, VNI=<NUM> in <FIG>.

Set a Next-header field in the overlay header, for example, next protocol=IPv6 in <FIG>.

Both the process of encapsulating the UDP header and the process of encapsulating the overlay header may be implemented by using an existing implementation, and details are not described herein.

It should be noted that some processing, involved in the encapsulation process, in a conventional technology is not changed in this embodiment of this application, and therefore is not listed herein one by one. For example, a hop limit of an inner IPv6 packet is decreased by one during encapsulation.

S703: The ingress node routes, through the established tunnel, the packet to the egress node that is indicated in the traversal indication information and that is in the IPv4 network.

After the packet reaches the egress node, the egress node decapsulates the packet and exposes the original IPv6 packet. Then, the egress node continues to perform forwarding in the IPv6 network according to an existing IPv6 or SRv6 forwarding process until the packet reaches the destination node.

For example, in <FIG>, after the packet reaches the egress node R5, the egress node R5 decapsulates the packet and continues to forward the packet to a next node R6 until the packet reaches a destination node R7.

Examples in which the IPv4 network is traversed in different encapsulation manners, namely, the VXLAN, the VXLAN-GPE, and the GENEVE, are used for description below.

<FIG> is a diagram of an application scenario in which a packet traverses an IPv4 network by using a VXLAN-GPE according to an embodiment of this application. The following describes, by using <FIG>, a processing process in the application scenario shown in <FIG>. <FIG> is a flowchart of a method in which an SRv6 packet traverses an IPv4 network by using a VXLAN-GPE according to an embodiment of this application.

S901: Ahead node (a node E) in an IPv6 network encapsulates, into an SRH header of the SRv6 packet, an SID advertised by an ingress node (a node <NUM>) in an IPv4 network. In this embodiment, the head node in the IPv6 network is a head node of an SRv6 tunnel established in the IPv6 network, namely, the <NUM>st node (namely, an ingress node of the packet in the SRv6 network) encountered after the packet enters the SRv6 tunnel, for example, the node E in <FIG> or the node R1 in <FIG>.

The SID of the node <NUM> uses the new SID type provided in this embodiment of this application. An example of the SID is shown in <FIG>. For a process in which the node E encapsulates the SID, refer to the embodiment shown in <FIG>.

S902: When the packet passes through a non-edge node (for example, a node <NUM> in <FIG>), perform forwarding according to a common IPv6 or SRv6 forwarding process.

It should be noted that, in this embodiment of this application, an edge node is a node that supports IPv6/IPv4 dual stack, and is connected to both the IPv6 network and the IPv4 network. The <NUM>st edge node reached by the packet in the transmission process is the ingress node in the IPv4 network.

S903: Determine whether the packet reaches the edge node (the node <NUM> in <FIG>), and if the packet does not reach the edge node, perform step S902, or if the packet reaches the edge node (that is, reaches the ingress node in the IPv4 network), perform steps S904 to S908.

Step S904: The edge node encapsulates an IPv4 packet header, a UDP header, and a VXLAN-GPE header outside an IPv6 packet header based on an indication of the SID.

As shown in <FIG>, when the packet reaches the node <NUM>, the original packet is encapsulated based on the indication of the corresponding SID in the SRH (that is, an indication of traversal indication information in the SID) by using the VXLAN-GPE tunnel, and the IPv4 header and the UDP header are added before the VXLAN-GPE header, to traverse the IPv4 network between the node <NUM> and the node <NUM>. A source address and a destination address of the IPv4 packet header may be respectively set to an interface address corresponding to the node <NUM> and an interface address corresponding to the node <NUM>, a UDP destination port number is <NUM>, the VNI is set based on an indication of the SID (for example, VNI=<NUM> in <FIG>), and the next protocol field in the VXLAN-GPE is set to "0x2" corresponding to the IPv6. <FIG> shows a format of a packet encapsulated in a manner of this embodiment. For a specific implementation of an encapsulation process, refer to step S702 in the embodiment shown in <FIG>.

S905: Forward the encapsulated packet in the IPv4 network according to an existing IPv4 forwarding process.

For a specific implementation, refer to an existing IPv4 forwarding processing manner.

S906: When the packet reaches a peer-end edge node (for example, the node <NUM> in <FIG>) indicated by the IPv4 destination address, the peer-end edge node decapsulates the IPv4 packet header, the UDP header, and the VXLAN-GPE header, to obtain the original IPv6 packet.

S907: Continue to forward the decapsulated packet in the IPv6 network according to the existing IPv6 or SRv6 forwarding process.

S908: Determine whether the packet reaches a target node (a node F in <FIG>), and if the packet does not reach the target node, continue to perform step S907; or if the packet reaches the target node, end the packet forwarding process.

The foregoing is the embodiment in which the VXLAN-GPE is used to traverse the IPv4 network.

In another embodiment, the GENEVE may alternatively be used as an encapsulation manner to traverse the IPv4 network. A difference between a case in which the GENEVE is used as the encapsulation manner to traverse the IPv4 network and a case in which the VXLAN-GPE is used to traverse the IPv4 network lies in that when encapsulation in step S904 is performed, the overlay header is a GENEVE header, the destination port of the UDP header is <NUM>, and a protocol type field in the GENEVE header is set to 0x86DD. <FIG> shows a format of a packet encapsulated by using GENEVE as an encapsulation manner.

In another embodiment, the VXLAN may alternatively be used as an encapsulation manner to traverse the IPv4 network. A difference between a case in which the VXLAN is used as the encapsulation manner to traverse the IPv4 network and a case in which the VXLAN-GPE is used to traverse the IPv4 network lies in that when encapsulation in step S904 is performed, the overlay header is a VXLAN header, and the destination port of the UDP header is <NUM>.

There is no Next protocol field in the VXLAN. By default, the packet header following the VXLAN header is an Ethernet header, and a source MAC address and a destination MAC address may be respectively set to an interface MAC address corresponding to the device <NUM> and an interface MAC address corresponding to the device <NUM>. <FIG> shows a format of a packet encapsulated by using a VXLAN as an encapsulation manner.

In another embodiment, NVGRE may alternatively be used as an encapsulation manner to traverse the IPv4 network. A difference between a case in which the NVGRE is used as the encapsulation manner to traverse the IPv4 network and a case in which the VXLAN-GPE is used to traverse the IPv4 network lies in that when encapsulation in step S904 is performed, the overlay header is an NVGRE header, and there is no UDP header. <FIG> shows a format of a packet encapsulated by using NVGRE as an encapsulation manner.

In this embodiment of this application, the new type of SID is extended to carry the traversal indication information, so that the head node not only has a capability of selecting the path in the IPv6 network (where the capability is implemented by using the SRv6 SRH), but also has a capability of selecting the exit of the tunnel in the IPv4 network. Therefore, the end-to-end path is controlled.

The new type of SID extended in this embodiment of this application can implement not only controlling on the end-to-end path by the head node, but also copying between the IPv6 packet and the IPv4 packet. The following uses an example, in which an in-situ Operation, Administration, and Maintenance in-situ Operation, Administration, and Maintenance (IOAM) header (where IOAM is sometimes also referred to as in-band Operation, Administration, and Maintenance in-band OAM, and this is not limited in this embodiment of this application) and/or a priority is copied, for description.

In an embodiment in which an IOAM header is copied between an IPv6 packet and an IPv4 packet, the IPv6 packet carries the IOAM header. A difference between this embodiment and the embodiment shown in <FIG> lies in that, in the packet forwarding process in step S902, information needs to be further collected along the path based on an indication of the IOAM header. In the packet encapsulation process in step S904, the edge node (the node <NUM>) further copies the IOAM header in the IPv6 extension header to the IPv4 extension header or the overlay header. In the forwarding process in step S905, information is further collected along the path based on the indication of the IOAM header. In the decapsulation process in step S906, the IOAM header, in the IPv4 extension header or the overlay header, is further copied to the IPv6 extension header, and in the forwarding process in step S907, information is further collected along the path based on the indication of the IOAM header.

In the foregoing embodiment, before the IPv6/SRv6 header is encapsulated into the overlay tunnel, a part of information may be copied into the IPv4/overlay header. For example, IOAM information in IPv6/SRv6 header can be copied to the IPv4 header or the overlay header. When forwarding is performed in an IPv4 domain, a network device adds to-be-collected information to an IOAM field. The data collected by IOAM field can be copied back into the IPv6/SRv6 header at the exit of the overlay tunnel. In this way, IOAM data can be collected on the end-to-end path.

In an embodiment in which a priority is copied, an IPv6 packet carries an APP-ID. The APP-ID may be mapped to different SR policies to ensure service level agreements Service Level Agreements (SLAs) of different applications. When the IPv6/SRv6 packet is forwarded in an IPv4 network, to ensure an SLA of an application in an IPv4 domain, the APP-ID can be mapped to a DSCP field in an IPv4 packet header, to indicate a forwarding priority in the IPv4 domain. Specifically, in a packet encapsulation process, an ingress node in the IPv4 network may set, in the DSCP field in the IPv4 packet header, APP-ID information carried in an IPv6 Hop-by-hop header or an SRH header. When the packet is forwarded in the IPv4 network, a priority is matched based on DSCP.

By using the copy function provided in this embodiment of this application, a feature of the packet in the IPv6 network is retained when the packet traverses the IPv4 network.

It should be noted that all nodes in this embodiment of this application are network devices, and may be switches, routers, or the like in a network.

<FIG> is a schematic diagram of a structure of a packet processing apparatus according to an embodiment of this application. The packet processing apparatus may be the node in the first network or the ingress node in the second network in any one of the foregoing embodiments. The node in the first network in the embodiments of this application is a head node of an SR tunnel established in the first network. The packet processing apparatus <NUM> may be a switch, a router, or another network device that forwards a packet. In this embodiment, the packet processing apparatus <NUM> includes a main control board <NUM>, an interface board <NUM>, and an interface board <NUM>. When there are a plurality of interface boards, a switching board (not shown in the figure) may be included. The switching board is configured to exchange data between the interface boards (where the interface board is also referred to as a line card or a service board).

The main control board <NUM> is configured to complete functions such as system management, device maintenance, and protocol processing. The interface boards <NUM> and <NUM> are configured to provide various service interfaces (for example, a POS interface, a GE interface, and an ATM interface), and forward a packet. The main control board <NUM> mainly includes three types of function units: a system management and control unit, a system clock unit, and a system maintenance unit. The main control board <NUM>, the interface board <NUM>, and the interface board <NUM> are connected to a system backboard by using a system bus to implement interworking. The interface board <NUM> includes one or more processors <NUM>. The processor <NUM> is configured to control and manage the interface board, communicate with a central processing unit on the main control board, and forward a packet. A memory <NUM> on the interface board <NUM> is configured to store a forwarding entry, and the processor <NUM> forwards a packet by searching the forwarding entry stored in the memory <NUM>.

The interface board <NUM> includes one or more network interfaces <NUM>, configured to receive a probe packet sent by a previous-hop network node, and send a processed probe packet to a next-hop network node based on an indication of the processor <NUM>. For a specific implementation process, refer to steps S601 and S603 in the embodiment shown in <FIG>, steps S701 and S703 in the embodiment shown in <FIG>, or steps S902, S905, and S907 in the embodiment shown in <FIG>.

The processor <NUM> is configured to perform processing steps and functions of the node in the first network or the ingress node in the second network described in the foregoing method embodiments. For details, refer to steps S601 and S602 in the embodiment shown in <FIG>, steps S701 and S702 in the embodiment shown in <FIG>, or steps S901 to S908 in the embodiment shown in <FIG>. Details are not described herein one by one again.

It should be noted that, as shown in <FIG>, this embodiment includes a plurality of interface boards, and uses a distributed forwarding mechanism. In this mechanism, operations on the interface board <NUM> are basically similar to operations on the interface board <NUM>. For brevity, details are not described again.

In addition, it should be noted that the processor <NUM> on the interface board <NUM> and/or the processor <NUM> in <FIG> may be dedicated hardware or a chip, for example, a network processor or an application-specific integrated circuit (application-specific integrated circuit), to implement the foregoing functions. This implementation is generally referred to as a manner of using dedicated hardware or a chip for processing on a forwarding plane. For a specific implementation of using the network processor, namely, the dedicated hardware or the chip, refer to descriptions of an embodiment shown in <FIG>. In another implementation, the processor <NUM> and/or <NUM> may alternatively be a general-purpose processor, for example, a general-purpose CPU, to implement the foregoing described functions. For an implementation of the general-purpose CPU, refer to descriptions in embodiments shown in <FIG>.

In addition, it should be noted that there may be one or more main control boards, and when there are a plurality of main control boards, the main control boards may include an active main control board and a standby main control board. There may be one or more interface boards, and a device having a stronger data processing capability provides more interface boards. If there are a plurality of interface boards, the plurality of interface boards can communicate with each other by using one or more switching boards, and the plurality of interface boards can jointly implement load sharing and redundancy backup. In a centralized forwarding architecture, the device may not need the switching board, and the interface board provides a function of processing service data of an entire system. In a distributed forwarding architecture, the device includes a plurality of interface boards. Data exchange between the plurality of interface boards may be implemented by using a switching board, and the plurality of interface boards can provide a large-capacity data exchange and processing capability. Therefore, a data access and processing capability of a network device in the distributed architecture is better than that of a device in the centralized architecture. A specific architecture that is to be used depends on a specific networking deployment scenario. This is not limited herein.

In a specific embodiment, the memory <NUM> may be a read-only memory (read-only memory, ROM), another type of static storage device that can store static information and instructions, a random access memory (random access memory, RAM), or another type of dynamic storage device that can store information and instructions, or may be an electrically erasable programmable read-only memory (electrically erasable programmable read-only memory, EEPROM), a compact disc read-only memory (compact disc read-only memory, CD-ROM) or another compact disc storage, an optical disc storage (including a compact optical disc, a laser disc, an optical disc, a digital versatile disc, a Blu-ray disc, and the like), a magnetic disk storage medium or another magnetic storage device, or any other medium that can be used to carry or store expected program code in a form of an instruction or a data structure and that can be accessed by a computer. However, the memory is not limited thereto. The memory <NUM> may exist independently, and is connected to the processor <NUM> by using a communication bus. The memory <NUM> may alternatively be integrated with the processor <NUM>.

The memory <NUM> is configured to store program code, and execution is controlled by the processor <NUM>, to perform the packet processing method provided in the foregoing embodiment. The processor <NUM> is configured to execute the program code stored in the memory <NUM>. The program code may include one or more software modules. The one or more software modules may be a software module provided in an embodiment in any one of <FIG>.

In a specific embodiment, the network interface <NUM> may be an apparatus that uses any transceiver, and is configured to communicate with another device or a communication network, for example, the Ethernet, a radio access network (radio access network, RAN), or a wireless local area network (wireless local area network, WLAN).

<FIG> is another schematic diagram of a structure of a packet processing apparatus according to an embodiment of this application. The packet processing apparatus may be the node in the first network or the ingress node in the second network in any one of the foregoing embodiments. The node in the first network in the embodiments of this application is a head node of an SR tunnel established in the first network. The packet processing apparatus <NUM> may be a switch, a router, or another network device that forwards a packet. In this embodiment, the packet processing apparatus <NUM> includes a main control board <NUM>, an interface board <NUM>, a switching board <NUM>, and an interface board <NUM>. The main control board <NUM> is configured to complete functions such as system management, device maintenance, and protocol processing. The switching board <NUM> is configured to exchange data between the forwarding boards (the forwarding board is also referred to as a line card or a service board). The interface boards <NUM> and <NUM> are configured to provide various service interfaces (for example, a POS interface, a GE interface, and an ATM interface), and forward a data packet. A control plane includes management and control units on the main control board <NUM> and management and control units on the interface board <NUM> and the interface board <NUM>. The main control board <NUM> mainly includes three types of function units: a system management and control unit, a system clock unit, and a system maintenance unit. The main control board <NUM>, the interface boards <NUM> and <NUM>, and the switching board <NUM> are connected to a system backboard by using a system bus to implement interworking. A central processing unit <NUM> on the interface board <NUM> is configured to control and manage the interface board, and communicate with a central processing unit on a main control board. A forwarding entry memory <NUM> on the interface board <NUM> is configured to store a forwarding entry, and a network processor <NUM> forwards a packet by searching the forwarding entry stored in the forwarding entry memory <NUM>.

The interface board <NUM> includes one or more network interfaces <NUM>, configured to receive a probe packet sent by a previous-hop network node, and send a processed probe packet to a next-hop network node based on an indication of the processor <NUM>. For a specific implementation process, refer to steps S601 and S603 in the embodiment shown in <FIG>, steps S701 and S703 in the embodiment shown in <FIG>, or steps S902, S905, and S907 in the embodiment shown in <FIG>. Details are not described herein one by one again.

It should be noted that, as shown in <FIG>, this embodiment includes a plurality of interface boards, and uses a distributed forwarding mechanism. In this mechanism, operations on the interface board <NUM> are basically similar to operations on the interface board <NUM>. For brevity, details are not described again. In addition, as described above, functions of the network processors <NUM> and <NUM> in <FIG> may be replaced with that of an application-specific integrated circuit (application-specific integrated circuit).

In addition, it should be noted that there may be one or more main control boards, and when there are a plurality of main control boards, the main control boards may include an active main control board and a standby main control board. There may be one or more interface boards, and a device having a stronger data processing capability provides more interface boards. There may also be one or more physical interface cards on the interface board. There may be no switching board or one or more switching boards. When there are a plurality of switching boards, load sharing and redundancy backup may be implemented together. In a centralized forwarding architecture, the device may not need the switching board, and the interface board provides a function of processing service data of an entire system. In a distributed forwarding architecture, the device may include at least one switching board, and data exchange between a plurality of interface boards is implemented by using the switching board, to provide a large-capacity data exchange and processing capability. Therefore, a data access and processing capability of a network device in the distributed architecture is better than that of a device in the centralized architecture. A specific architecture that is to be used depends on a specific networking deployment scenario. This is not limited herein.

Refer to <FIG>. An embodiment of this application further provides a packet processing apparatus <NUM>. The apparatus may be used in a node in a network. The node is a head node of an SR tunnel established in the network. For example, the node may implement a function of the head node of the SR tunnel shown in <FIG> or <FIG>. In a specific embodiment, the packet processing apparatus includes a determining unit <NUM>, a packet processing unit <NUM>, and a packet sending unit <NUM>.

The determining unit <NUM> is configured to perform step S601 in the embodiment shown in <FIG>, that is, determine an end-to-end transmission path for a packet, where the transmission path includes a transmission path in a first network and a path traversing a second network.

The packet processing unit <NUM> is configured to perform step S602 in the embodiment shown in <FIG>, that is, add end-to-end path information to the packet based on the determined transmission path, where the path information includes traversal indication information, and the traversal indication information indicates an egress node of the packet in the second network.

The packet sending unit <NUM> is specifically configured to send the packet processed by the packet processing unit <NUM>. Specifically, the packet sending unit <NUM> may send, to an ingress node in the second network through the first network, the packet to which the traversal indication information is added, to indicate the ingress node in the second network to encapsulate and transmit the packet based on the egress node that is specified in the traversal indication information and that is located in the second network. For a specific implementation process, refer to step S601 in the embodiment shown in <FIG> and step S901 in the embodiment shown in <FIG>.

In a specific implementation, the packet processing apparatus <NUM> may further include a receiving unit <NUM>, configured to receive at least one SID advertised by the ingress node in the second network, where different SIDs advertised by the ingress node carry different traversal indication information.

When adding the end-to-end path information to the packet, the packet processing unit <NUM> uses an SID corresponding to the path that is determined by the determining unit based on the traversal indication information and that traverses the second network as the SID of the ingress node in the second network, and adds the SID to the end-to-end path information.

For a specific implementation process of the receiving unit <NUM> and the packet processing unit <NUM>, refer to the descriptions of the processing process of R3 node in the embodiment shown in <FIG> and the descriptions of step S901 in the embodiment shown in <FIG>.

Refer to <FIG>. An embodiment of this application further provides a packet processing apparatus <NUM>. The apparatus may be used in an edge node in a network, and the node may implement a function of the ingress node shown in <FIG> or <FIG>.

In a specific embodiment, the packet processing apparatus includes a packet obtaining unit <NUM>, a packet processing unit <NUM>, and a packet sending unit <NUM>.

The packet obtaining unit <NUM> is configured to receive a packet from a first network, where the packet carries traversal indication information, and the traversal indication information indicates an egress node of the packet in a second network. For a specific implementation process, refer to specific descriptions in the embodiments shown in <FIG> and <FIG>.

The packet processing unit <NUM> is configured to encapsulate the packet based on the traversal indication information, to change a format of the packet to a format supported by the second network, where a destination address of the encapsulated packet is the egress node indicated in the traversal indication information. For a specific implementation process, refer to step <NUM> in the embodiment shown in <FIG>.

The packet sending unit <NUM> is configured to route the encapsulated packet to the egress node.

In a specific implementation, the packet processing apparatus <NUM> may further include an advertising unit <NUM>, configured to advertise at least one SID, where the SID carries the traversal indication information, and when a plurality of SIDs are advertised, different SIDs carry different traversal indication information. For a specific implementation process, refer to the descriptions of the processing process of R3 node in the embodiment shown in <FIG> and the descriptions of step S901 in the embodiment shown in <FIG>.

Refer to <FIG>. An embodiment of this application provides a packet processing apparatus <NUM>. The packet processing apparatus <NUM> may implement the function of the head node of the SR tunnel in the embodiments shown in <FIG> and <FIG>. The packet processing apparatus includes at least one processor <NUM> and at least one communication interface <NUM>.

In addition, a memory <NUM> may be further included, configured to store instructions. The memory <NUM> may be a cache memory inside the processor, or may be a memory outside the processor. When the units described in the embodiment of <FIG> are implemented by using software, software or program code required for performing the functions of the packet processing unit <NUM> and the packet sending unit <NUM> in <FIG> is stored in the memory <NUM>.

The processor <NUM> is configured to execute the instructions in the memory <NUM>, to perform the foregoing processing steps applied to the head node of the SR tunnel in the embodiment shown in <FIG> or <FIG>.

The communication interface <NUM> is configured to perform communication.

The memory <NUM> (when the processor is external), the processor <NUM>, and the communication interface <NUM> are connected to each other by using a bus <NUM>. The bus <NUM> may be a peripheral component interconnect (peripheral component interconnect, PCI for short) bus, an extended industry standard architecture (extended industry standard architecture, EISA for short) bus, or the like. Buses may be classified into an address bus, a data bus, a control bus, and the like. For ease of representation, only one thick line is used to represent the bus in <FIG>, but this does not mean that there is only one bus or only one type of bus.

In a specific embodiment, the processor <NUM> is configured to determine an end-to-end transmission path for a packet, add end-to-end path information to the packet based on the determined transmission path, and send, to an ingress node in the second network through the communication interface <NUM>, the packet to which traversal indication information is added. For a specific process, refer to specific descriptions in <FIG> and <FIG>.

Refer to <FIG>. An embodiment of this application provides a packet processing apparatus <NUM>. The packet processing apparatus <NUM> may implement the function of the ingress node in the embodiments shown in <FIG> and <FIG>. The packet processing apparatus includes at least one processor <NUM> and at least one communication interface <NUM>.

The processor <NUM> is configured to execute the instructions in the memory <NUM>, to perform the foregoing processing steps applied to the ingress node in the embodiments shown in <FIG> and <FIG>.

In a specific embodiment, the processor <NUM> is configured to receive a packet from a first network; encapsulate the packet based on traversal indication information in the packet, to change a format of the packet to a format supported by a second network; set a destination address of the encapsulated packet as an egress node indicated in the traversal indication information; and route the encapsulated packet to the egress node. For a specific process, refer to specific descriptions in the embodiments shown in <FIG> and <FIG>.

The communication interface <NUM> is configured to send and receive a packet. For a specific process, refer to specific descriptions in the embodiments shown in <FIG> and <FIG>.

The memory <NUM> or the memory <NUM> may be a random access memory (random access memory, RAM), a flash (flash), a read-only memory (read-only memory, ROM), an erasable programmable read-only memory (erasable programmable read-only memory, EPROM), an electrically erasable programmable read-only memory (electrically erasable programmable read-only memory, EEPROM), a register (register), a hard disk, a removable hard disk, a CD-ROM, or any other form of storage medium known to a person skilled in the art, or may be a cache in a processor.

The processor <NUM> or the processor <NUM> may be, for example, a central processing unit (central processing unit, CPU), a network processor, a general-purpose processor, a digital signal processor (digital signal processor, DSP), an application-specific integrated circuit (application specific integrated circuit, ASIC), a field programmable gate array (field programmable gate array, FPGA), or another programmable logic component, a transistor logic device, a hardware component, or any combination thereof. The processing module may implement or execute various example logical blocks, modules, and circuits described with reference to content disclosed in this application. Alternatively, the processor may be a combination of processors implementing a computing function, for example, a combination of one or more microprocessors, or a combination of a DSP and a microprocessor.

The communication interface <NUM> or the communication interface <NUM> may be, for example, an interface card, and may be an Ethernet (Ethernet) interface or an asynchronous transfer mode (asynchronous transfer mode, ATM) interface.

An embodiment of this application further provides a chip. The chip is disposed in the packet processing apparatus shown in <FIG> or <FIG>. The packet processing apparatus is the head node of the SR tunnel in the method embodiment. The chip includes a processor and an interface circuit.

The interface circuit is configured to receive instructions and transmit the instructions to the processor.

The processor is configured to receive the instructions from the interface circuit, and execute the foregoing processing steps that are applied to the head node of the SR tunnel in the embodiments shown in <FIG> and <FIG>.

In a specific embodiment, the processor is configured to determine an end-to-end transmission path for a packet, add end-to-end path information to the packet based on the determined transmission path, and send, to an ingress node in a second network through the communication interface <NUM>, the packet to which traversal indication information is added. For a specific process, refer to specific descriptions in <FIG> and <FIG>.

An embodiment of this application further provides a chip. The chip is disposed in the packet processing apparatus shown in <FIG> or <FIG>. The packet processing apparatus is the ingress node in the method embodiment. The chip includes a processor and an interface circuit.

The processor is configured to receive the instructions from the interface circuit, and execute the foregoing processing steps that are applied to the ingress node in the embodiments shown in <FIG> and <FIG>.

In a specific embodiment, the processor is configured to receive a packet from a first network; encapsulate the packet based on traversal indication information in the packet, to change a format of the packet to a format supported by a second network; set a destination address of the encapsulated packet as an egress node indicated in the traversal indication information; and route the encapsulated packet to the egress node. For a specific process, refer to specific descriptions in the embodiments shown in <FIG> and <FIG>.

An embodiment of this application further provides a network system. The network system includes a device in a first network and a device in a second network. The device in the first network includes a node, and the device in the second network includes an edge node connected to the first network. The edge node is also located in the first network, and supports transmission protocols of the first network and the second network. A packet sent by the node in the first network passes through the edge node in the second network and reaches a destination node through the second network. The node in the first network in the embodiments of this application is a head node of an SR tunnel established in the first network.

The node in the network system may perform steps of the head node of the SR tunnel in the embodiments shown in <FIG> and <FIG>, and details are not described herein again. Alternatively, correspondingly, the node in the network system is the packet processing apparatus <NUM> or <NUM> in the embodiment shown in <FIG> or <FIG>.

The edge node in the network system may perform steps of the ingress node in the embodiments shown in <FIG> and <FIG>, and details are not described herein again. Alternatively, correspondingly, the edge node in the network system is the packet processing apparatus <NUM> or <NUM> in the embodiment shown in <FIG> or <FIG>.

An embodiment of this application further provides a computer-readable storage medium, including instructions. When the instructions are run on a computer, the computer is enabled to perform the foregoing packet processing method applied to the packet processing apparatus <NUM>.

An embodiment of this application further provides a computer-readable storage medium, including instructions. When the instructions are run on a computer, the computer is enabled to perform the packet processing method applied to the packet processing apparatus <NUM>.

It may be clearly understood by a person skilled in the art that, for purpose of convenient and brief description, for a detailed working process of the foregoing system, apparatus, and unit, refer to a corresponding process in the foregoing method embodiments, and details are not described herein again.

In the several embodiments provided in this application, it should be understood that the disclosed system, apparatus and method may be implemented in other manners. For example, the unit division is merely logical service division and may be other division in actual implementation. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections may be implemented through some interfaces.

A part or all of the units may be selected based on an actual requirement to achieve the objectives of the solutions of the embodiments.

In addition, service units in the embodiments of this application may be integrated into one processing unit, or each of the units may exist alone physically, or two or more units are integrated into one unit. The integrated unit may be implemented in a form of hardware, or may be implemented in a form of a software service unit.

When the service unit is implemented in the form of a software functional unit and sold or used as an independent product, the integrated unit may be stored in a computer-readable storage medium. Based on such an understanding, the technical solutions of this application essentially, or the part contributing to the conventional technology, or all or some of the technical solutions may be implemented in the form of a software product. The software product is stored in a storage medium and includes a plurality of instructions for instructing a computer device (which may be a personal computer, a server, or a network device) to perform all or some of the steps of the methods described in the embodiments of this application. The storage medium includes any medium that can store program code, such as a USB flash drive, a removable hard disk, a read-only memory (Read-Only Memory, ROM), a random access memory (Random Access Memory, RAM), a magnetic disk, or an optical disc.

Persons skilled in the art should be aware that in the foregoing one or more examples, the services described in the present invention may be implemented by using hardware, software, firmware, or any combination thereof. When the present invention is implemented by software, the services may be stored in a computer-readable medium or transmitted as one or more instructions or code in the computer-readable medium. The computer-readable medium includes a computer storage medium and a communication medium, where the communication medium includes any medium that facilitates transmission of a computer program from one place to another. The storage medium may be any available medium accessible to a general-purpose or dedicated computer.

Claim 1:
A packet processing method, comprising:
determining (S601), by a node in a first network, where the node in the first network is a head node of a segment routing, SR, tunnel established in the first network, a transmission path for a packet, wherein the transmission path comprises a path in the first network and a path traversing a second network;
adding (S602), by the node in the first network, path information to the packet based on the determined transmission path, wherein the path information comprises traversal indication information, and the traversal indication information indicates an ingress node and an egress node of the packet in the second network; and
sending (S603), by the node in the first network based on the path information, the packet to an ingress node in the second network through the first network, to indicate the ingress node in the second network to transmit the packet by using the egress node specified in the traversal indication information, wherein after receiving the packet, the ingress node in the second network encapsulates (S702) the packet based on the traversal indication information in the packet to change a format of the packet to a format supported by the second network; wherein
the first network is an IPv6 network, the second network is an IPv4 network, and the packet is an IPv6 packet.