Method for synchronizing topology information in SFC network, and routing network element

1. A method implemented by a first network element in a service function chain (SFC) network and serving as a first service function forwarder (SFF), the method comprising:

establishing a first Border Gateway Protocol (BGP) connection to a second network element;

sending a first BGP update message to the second network element, wherein the first BGP update message comprises network layer reachability information (NLRI), wherein the NLRI comprises a type field, service function (SF) information about an SF connected to the first network element, and an identifier of the first network element, wherein the type field indicates that the NLRI comprises the SF information, and wherein the SF information comprises an identifier of the SF and a service type of the SF;

establishing a second BGP connection to an upper-level SFF;

determining that topology information in a first subdomain is synchronized, wherein the first network element is a top-level classifier (CF) in the first subdomain;

generating a service digest of the first subdomain based on topology information of routing network elements in the first subdomain, wherein the service digest comprises an identifier of the first subdomain and a service type of the first subdomain; and

sending a fourth BGP update message to the upper-level SFF,

wherein the fourth BGP update message comprises the service digest.

2. The method of claim 1 , wherein the first network element is configured as a route reflector (RR), and wherein the method further comprises:

receiving a second BGP update message from a network element A, wherein the second BGP update message comprises second topology information of the network element A; and

sending a third BGP update message to a network element B, wherein the third BGP update message comprises the second topology information.

3. The method of claim 1 , wherein the SFC network further comprises a first autonomous system (AS) domain and a second AS domain, wherein the first network element is a first top-level classifier (CF) in the first AS domain, and wherein the method further comprises:

establishing a second BGP connection to a second top-level CF in the second AS domain;

determining that topology information in the first AS domain is successfully synchronized;

generating a service digest of the first AS domain based on topology information of routing network elements in the first AS domain, wherein the service digest comprises an identifier of the first AS domain and a service type of the first AS domain; and

sending a fifth BGP update message to the second top-level CF, wherein the fifth BGP update message comprises the service digest.

4. The method of claim 1 , wherein the NLRI is SFC NLRI.

5. The method of claim 1 , wherein the second network element is a second SFF.

6. The method of claim 1 , wherein the second network element is a classifier (CF).

7. The method of claim 1 , wherein the second network element is a controller.

8. The method of claim 1 , wherein the SF provides an antivirus function, a firewall function, an application caching and acceleration function, or a web page optimization function.

9. A first network element in a service function chain (SFC) network, serving as a first service function forwarder (SFF), and comprising:

a processor configured to:

establish a first Border Gateway Protocol (BGP) connection to a second network element;

establish a second BGP connection to an upper-level SFF;

determine that topology information in a first subdomain is synchronized, wherein the first network element is a top-level classifier (CF) in the first subdomain; and

generate a service digest of the first subdomain based on topology information of routing network elements in the first subdomain, wherein the service digest comprises an identifier of the first subdomain and a service type of the first subdomain; and

a network interface coupled to the processor and configured to:

send a first BGP update message to the second network element, wherein the first BGP update message comprises network layer reachability information (NLRI), wherein the NLRI comprises a type field, service function (SF) information about an SF connected to the first network element, and an identifier of the first network element, wherein the type field indicates that the NLRI comprises the SF information, and wherein the SF information comprises an identifier of the SF and a service type of the SF; and

send a fourth BGP update message to the upper-level SFF,

wherein the fourth BGP update message comprises the service digest.

10. The first network element of claim 9 , wherein the first network element is configured as a route reflector (RR), and wherein the network interface is further configured to:

receive a second BGP update message from a network element A, wherein the second BGP update message comprises second topology information of the network element A; and

send a third BGP update message to a network element B, wherein the third BGP update message comprises the second topology information.

11. The first network element of claim 9 , wherein the SFC network further comprises a first autonomous system (AS) domain and a second AS domain, wherein the first network element is a first top-level classifier (CF) in the first AS domain, and wherein the processor is further configured to:

establish a second BGP connection to a second top-level CF in the second AS domain;

determine that topology information in the first AS domain is successfully synchronized; and

generate a service digest of the first AS domain based on topology information of routing network elements in the first AS domain after determining that the topology information in the first AS domain is successfully synchronized, wherein the service digest comprises an identifier of the first AS domain and a service type of the first AS domain,

wherein the network interface is further configured to send a fifth BGP update message to the second top-level CF, and wherein the fifth BGP update message comprises the service digest.

12. The first network element of claim 9 , wherein the NLRI is SFC NLRI.

13. The first network element of claim 9 , wherein the second network element is a second SFF.

14. The first network element of claim 9 , wherein the second network element is a classifier (CF) or a controller.

15. The first network element of claim 9 , wherein the SF provides an antivirus function, a firewall function, an application caching and acceleration function, or a web page optimization function.

16. A computer program product comprising instructions that are stored on a non-transitory computer-readable medium and that, when executed by a processor, cause a first network element serving as a first service function forwarder (SFF) to:

establish a first Border Gateway Protocol (BGP) connection to a second network element;

send a first BGP update message to the second network element, wherein the first BGP update message comprises network layer reachability information (NLRI), wherein the NLRI comprises a type field, service function (SF) information about an SF connected to the first network element, and an identifier of the first network element, wherein the type field indicates that the NLRI comprises the SF information, and wherein the SF information comprises an identifier of the SF and a service type of the SF;

establish a second BGP connection to an upper-level SFF;

determine that topology information in a first subdomain is synchronized, wherein the first network element is a top-level classifier (CF) in the first subdomain;

generate a service digest of the first subdomain based on topology information of routing network elements in the first subdomain, wherein the service digest comprises an identifier of the first subdomain and a service type of the first subdomain; and

send a fourth BGP update message to the upper-level SFF,

wherein the fourth BGP update message comprises the service digest.

17. The computer program product of claim 16 , wherein the first network element is configured as a route reflector (RR), and wherein the instructions, when executed by the processor, further cause the first network element to:

receive a second BGP update message from a network element A, wherein the second BGP update message comprises second topology information of the network element A; and

send a third BGP update message to a network element B, wherein the third BGP update message comprises the second topology information.

18. The computer program product of claim 16 , wherein the NLRI further comprises an identifier of the first network element.

19. The computer program product of claim 16 , wherein the SF provides an antivirus function, a firewall function, an application caching and acceleration function, or a web page optimization function.

20. The computer program product of claim 16 , wherein the NLRI is SFC NLRI.