Route recursion control method, device, and system

1. A first network device, comprising:

a processor; and

a memory coupled to the processor and configured to store instructions that, when executed by the processor, cause the first network device to be configured to:

receive Border Gateway Protocol (BGP) routing information from a second network device, wherein the BGP routing information comprises a destination address and a next-hop address for the destination address;

determine a manner of performing route recursion on the next-hop address based on attribute information, wherein the manner of performing route recursion comprises either Internet Protocol (IP) recursion or tunnel recursion, wherein the attribute information comprises a BGP extended communities attribute, wherein the BGP extended communities attribute comprises a type field, a flag field, a first value field, and a second value field, wherein the type field indicates to control the route recursion of the next hop address, wherein the flag field controls the manner of performing the route recursion of the next-hop address, wherein the first value field indicates a first type of the IP recursion, and wherein the second value field indicates a second type of the tunnel recursion;

perform the IP recursion on the next-hop address when the attribute information indicates to perform the IP recursion on the next-hop address, wherein the IP recursion comprises determining a direct next-hop address; and

perform the tunnel recursion on the next-hop address when the attribute information indicates to perform the tunnel recursion, wherein the tunnel recursion comprises determining a tunnel identifier.

2. The first network device of claim 1 , wherein the instructions further cause the first network device to be configured to skip performing the route recursion on the next-hop address when the attribute information indicates not to perform the route recursion.

3. The first network device of claim 1 , wherein the IP recursion comprises common IP recursion or flow specification (FlowSpec) route recursion.

4. The first network device of claim 1 , wherein the tunnel recursion comprises multi-protocol label switching (MPLS) label switched path (LSP) tunnel recursion, resource reservation protocol-traffic engineering (RSVP-TE) tunnel recursion, segment routing-traffic engineering (SR-TE) tunnel recursion, segment routing-best effort (SR-BE) tunnel recursion, generic routing encapsulation (GRE) tunnel recursion, Internet Protocol version 4 (IPv4) tunnel recursion, or Internet Protocol version 6 (IPv6) tunnel recursion.

5. The first network device of claim 1 , wherein the manner of performing route recursion further comprises both the IP recursion and the tunnel recursion, wherein the instructions further cause the first network device to be configured to perform the IP recursion and the tunnel recursion on the next-hop address when the attribute information indicates to perform the IP recursion and the tunnel recursion on the next-hop address, wherein the first type of the IP recursion comprises common IP recursion or FlowSpec route recursion, and wherein the second type of the tunnel recursion comprises multi-protocol label switching (MPLS LSP) tunnel recursion, resource reservation protocol-traffic engineering (RSVP-TE) tunnel recursion, segment routing-traffic engineering (SR-TE) tunnel recursion, segment routing-best effort (SR-BE) tunnel recursion, generic routing encapsulation (GRE) tunnel recursion, Internet Protocol version 4 (IPv4) tunnel recursion, or Internet Protocol version 6 (IPv6) tunnel recursion.

6. The first network device of claim 1 , wherein the IP recursion comprises a common IP recursion type.

7. The first network device of claim 1 , wherein the IP recursion comprises a FlowSpec route recursion type.

8. The first network device of claim 1 , wherein the tunnel recursion comprises a multi-protocol label switching (MPLS LSP) tunnel recursion type.

9. The first network device of claim 1 , wherein the tunnel recursion comprises a resource reservation protocol-traffic engineering (RSVP-TE) tunnel recursion type.

10. The first network device of claim 1 , wherein the tunnel recursion comprises a segment routing-traffic engineering (SR-TE) tunnel recursion type.

11. The first network device of claim 1 , wherein the tunnel recursion comprises an IP tunnel recursion type.

12. A system, comprising:

a first network device comprising:

a first processor and a first memory; and

a second network device comprising:

a second processor; and a second memory coupled to the second processor and configured to store instructions that, when executed by the second processor, cause the second network device to be configured to:

obtain Border Gateway Protocol (BGP) routing information, wherein the BGP routing information comprises a destination address, a next-hop address for the destination address, and attribute information, wherein the attribute information indicates a manner of performing route recursion on the next-hop address by the first network device, wherein the manner of performing route recursion comprises either Internet Protocol (IP) recursion or tunnel recursion, wherein the attribute information comprises a BGP extended communities attribute, wherein the BGP extended communities attribute comprises a type field, a flag field, a first value field, and a second value field, wherein the type field indicates to control the route recursion of the next hop address, wherein the flag field controls the manner of performing the route recursion of the next-hop address, wherein the first value field indicates a first type of the IP recursion, and wherein the second value field indicates a second type of the tunnel recursion; and

send the BGP routing information to the first network device;

wherein the first network device is configured to:

perform the IP recursion on the next-hop address when the attribute information indicates to perform the IP recursion on the next-hop address, wherein the IP recursion comprises determining a direct next-hop address; and

perform the tunnel recursion on the next-hop address when the attribute information indicates to perform the tunnel recursion, wherein the tunnel recursion comprises determining a tunnel identifier.

13. The system of claim 12 , wherein the manner of performing the route recursion on the next-hop address comprises one of:

skipping performing the route recursion on the next-hop address;

performing the IP recursion on the next-hop address, wherein the first type of the IP recursion comprises common IP recursion or FlowSpec route recursion;

performing the tunnel recursion on the next-hop address, wherein the second type of the tunnel recursion comprises multi-protocol label switching (M-PLS) label switched path (LSP) tunnel recursion, resource reservation protocol-traffic engineering (RSVP-TE) tunnel recursion, segment routing-traffic engineering (SR-TE) tunnel recursion, segment routing-best effort (SR-BE) tunnel recursion, generic routing encapsulation (GRE) tunnel recursion, Internet Protocol version 4 (IPv4) tunnel recursion, or Internet Protocol version 6 (IPv6) tunnel recursion; or

performing the IP recursion and the tunnel recursion on the next-hop address.

14. The system of claim 12 , wherein before obtaining the BGP routing information, the instructions further cause the second network device to be configured to obtain policy information, and wherein the policy information indicates for the second network device to add the attribute information to the BGP routing information that is to be advertised to the first network device.

15. The system of claim 14 , wherein the instructions further cause the second network device to be configured to obtain the BGP routing information based on the policy information.

16. The system of claim 14 , wherein the policy information further comprises specified address information, wherein the specified address information indicates an address set, and wherein the policy information indicates for the second network device to add the attribute information to the BGP routing information that comprises the destination address and that is to be advertised to the first network device.

17. The system of claim 16 , wherein the instructions further cause the second network device to be configured to obtain the BGP routing information based on the policy information when the destination address is in the address set.

18. The system of claim 14 , wherein the second network device obtains the policy information by:

obtaining the policy information based on a command line configuration;

receiving a message from a control and management device, wherein the message comprises the policy information; and

running algorithm software to automatically generate the policy information.

19. A system, comprising:

a first network device comprising a first processor and a first memory;

a second network device comprising a second processor and a second memory; and

a control and management device comprising a third processor; and

a third memory coupled to the third processor and configured to store instructions that, when executed by the third processor, cause the control and management device to be configured to:

generate a message comprising policy information, wherein the policy information indicates for the second network device to add attribute information to Border Gateway Protocol (BGP) routing information that is to be advertised to the first network device, wherein the BGP routing information comprises a destination address, a next-hop address for the destination address, and the attribute information, wherein the attribute information indicates a manner of performing route recursion on the next-hop address by the first network device, wherein the manner of performing route recursion comprises either Internet Protocol (IP) recursion or tunnel recursion, wherein the attribute information comprises a BGP extended communities attribute, wherein the BGP extended communities attribute comprises a type field, a flag field, a first value field, and a second value field, wherein the type field indicates to control the route recursion of the next hop address, wherein the flag field controls the manner of performing the route recursion of the next-hop address, wherein the first value field indicates a first type of the IP recursion, and wherein the second value field indicates a second type of the tunnel recursion; and

send the message to the second network device;

where the second network device is configured to send the BGP routing information to the first network device;

wherein the first network device is configured to:

perform the IP recursion on the next-hop address when the attribute information indicates to perform the IP recursion on the next-hop address, wherein the IP recursion comprises determining a direct next-hop address; and

perform the tunnel recursion on the next-hop address when the attribute information indicates to perform the tunnel recursion, wherein the tunnel recursion comprises determining a tunnel identifier.

20. The system of claim 19 , wherein the policy information further comprises specified address information, wherein the specified address information indicates an address set, and wherein the policy information indicates for the second network device to add the attribute information to the BGP routing information that comprises the destination address in the address set and that is to be advertised to the first network device.