METHODS AND SYSTEMS WITH ENHANCED ROBUSTNESS FOR MULTI-CHASSIS LINK AGGREGATION GROUP

• US 20140369186A1
• Filed: 06/17/2013
• Published: 12/18/2014
• Est. Priority Date: 06/17/2013
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Carvalho, Allwyn, Ernstrom, Lars, Gorla, Veeranjaneyulu, Wang, Anjing, Sasidharan Pillai, Kiran, Renganathan, Chezhian
• Granted Patent: US 9,264,302 B2
• Time in Patent Office: Days
• US Class Current: 370/228
• CPC Class Codes: H04L 41/0668 by dynamic selection of recovery network elements, e.g. replacement by the most appropriate element after failure
• CPC Class Codes: H04L 45/586 of virtual routers
• CPC Class Codes: H04L 49/55 Prevention, detection or correction of errors

Abstract

A method implemented for a link aggregation group is disclosed. The link aggregation group contains a local interface and a remote interface. The local interface is a logical interface formed by a plurality of network elements including a local network element and a peer network element. The local network element communicates with the peer network element through an inter-peer link. The method starts with determining that the local network element is active by checking that an aggregate state of the links coupled to the local network element is active. The method continues with detecting an anomaly of the active links and sending a notification to the peer network element about the anomaly. Then method continues with receiving an activation confirmation that the peer network element is ready for switching and switching traffic from the active links to the inter-peer link in response to receiving the activation confirmation.

Claims

1. A method implemented for a link aggregation group, wherein the link aggregation group contains a local interface and a remote interface, wherein the local interface is a logical interface formed by a plurality of network elements, wherein the logical interface includes a local network element and a peer network element, wherein the remote interface is at a remote network element coupled to the link aggregation group through links of the link aggregation group, wherein the local network element communicates with the peer network element through an inter-peer link, and wherein the method implemented at the local network element, the method comprising:

determining that the local network element is active by checking that an aggregate state of the links coupled to the local network element is active, wherein the aggregate state of the links being active indicates that a number of the links are up and transmitting traffic of the link aggregation group;

detecting an anomaly of the active links of the link aggregation group;

sending a notification to the peer network element about the anomaly;

receiving an activation confirmation that the peer network element is ready for switching; and

switching traffic of the link aggregation group from the active links to the inter-peer link in response to receiving the activation confirmation.

2. The method of claim 1, wherein determining links coupled to the local network element being active further determines an aggregate state of links coupled to the peer network element.

3. The method of claim 1, wherein the aggregate state of the links can further be standby or down, wherein the standby links are up but not transmitting traffic of the link aggregation group, and wherein down links do not carry traffic.

4. The method of claim 1, wherein a policy is placed to determine the aggregate state of the links coupled to the local network element.

5. The method of claim 1, wherein the switched traffic is forwarded based on matching an IP address prefix of one of a static route and a route learned dynamically through a protocol exchange.

6. The method of claim 1, wherein the confirmation is sent by the peer network element, and the peer network element performs:

activating links of the link aggregation group coupled to the peer network element after receiving the notification about the anomaly; and

sending the activation confirmation to the local network element after activation of the links of the link aggregation group completes.

7. The method of claim 1, wherein detecting the anomaly of active links of the link aggregation group is based on a threshold number of links of the active links malfunctioning.

8. The method of claim 7, wherein the threshold number of links of the active links for detecting the anomaly is configurable.

9. The method of claim 1, wherein determining the local network element being active is performed through a protocol exchange with the peer network element of the link aggregation group.

10. The method of claim 9, wherein the protocol exchange complies with an implementation of inter-chassis control protocol (ICCP), and wherein the protocol exchange is performed through the inter-peer link.

11. A method implemented for a link aggregation group, wherein the link aggregation group contains a local interface and a remote interface, wherein the local interface is a logical interface formed by a plurality of network elements, wherein the logical interface includes a local network element and a peer network element, wherein the remote interface is at a remote network element coupled to the link aggregation group through links of the link aggregation group, wherein the local network element communicates with the peer network element through an inter-peer link, and wherein the method implemented at the local network element, the method comprising:

determining that the local network element is active or standby by checking that an aggregate state of the links coupled to the local network element is active or standby, wherein the aggregate state of the links being active indicates that a number of the links are up and transmitting traffic of the link aggregation group, and wherein the aggregate state of the links being standby indicates that a number of the links are up but not transmitting traffic of the link aggregation group;

upon the local network element being active,

setting a primary next-hop interface address of the local network element to be an IP address belonging to a subnet of the link aggregation group; and

setting a backup next-hop interface address of the local network element to be an IP address of the peer network element, wherein the primary and backup next-hop interface addresses are used for resolving addresses for routing traffic; and

upon the local network element being standby,

setting the primary next-hop interface address of the local network element to be IP address of the peer network element; and

setting the backup next-hop interface address of the local network element to be the IP address belonging to the subnet of the link aggregation group.

12. The method of claim 11, wherein determining the local network element being active or standby further includes determining the peer network element being active or standby.

13. The method of claim 11, wherein the aggregate state of the links further includes down, wherein down links do not carry traffic, and wherein no setting of next-hop interface address at the network element coupled to the down links is performed.

14. The method of claim 11, wherein a policy is placed to determine the aggregate state of the links coupled to the local network element.

15. The method of claim 11, further comprising:

setting an IP subnet prefix for the local interface.

16. The method of claim 15, further comprising synchronizing settings to the peer network element by a protocol exchange between the local network element and the peer network element, the setting including at least one of:

the IP address settings;

link aggregation states; and

the IP subnet prefix.

17. The method of claim 16, wherein the local network element contains at least one of a routing information base (RIB) and forwarding information base (FIB), wherein the RIB contains routing information to aid the local network element to route traffic through an implementation of Internet Protocol (IP) using IP addresses, wherein the FIB contains forwarding information to aid the local network element to forward traffic at a faster speed than routing based on the RIB, wherein the protocol exchange passes information within at least one of the FIB and RIB associated with the local network element and the peer network element.

18. The method of claim 11, further comprising:

receiving a packet after the determination that the local network element is standby; and

upon determining that the primary next-hop specified by the primary next-hop interface address works properly,

sending an address resolution request to resolve an address for the packet to a destination specified by the primary next-hop interface address of the local network element;

receiving a reply to the address resolution request; and

routing the packet and following packets addressed to the address using the information embedded in the reply to the address resolution request.

19. The method of claim 18, further comprising:

upon determining that the primary next-hop specified by the primary next-hop interface address does not work properly,

sending the address resolution request to a destination specified by the backup next-hop interface address of the local network element;

receiving a reply to the address resolution request; and

routing the packet and following packets addressed to the address using the information embedded in the reply to the address resolution request.

20. The method of claim 18, wherein the address resolution request complies with one of an address resolution protocol (ARP) and a neighbor discovery (ND) protocol.

21. A network element communicatively coupled with aggregation ports through links of a link aggregation group, wherein the link aggregation group contains a local interface and a remote interface, wherein the local interface is a logical interface formed by a plurality of network elements, wherein the logical interface includes the network element and a peer network element, wherein the remote interface is at a remote network element coupled to the link aggregation group through links of the link aggregation group, wherein the network element communicates with the peer network element through an inter-peer link, the network element comprising:

an aggregation interface configured to interact with links of the link aggregation group and detect anomalies of the links; and

a link aggregation group processor, including;

a link state checker configured to determine that the network element is active by checking that an aggregate state of the links coupled to the network element is active, wherein the aggregate state of the links being active indicates that a number of the links are up and transmitting traffic of the link aggregation group;

an event handler configured to send a notification to the peer network element when an anomaly is detected at the aggregation interface;

the event handler further configured to receive an activation confirmation that the peer network element is ready for switching; and

the event handler further configured to switch traffic of the link aggregation group from the active links to the inter-peer link in response to receiving the activation confirmation.

22. The network element of claim 21, wherein determining links coupled to the network element being active further determines an aggregate state of links coupled to the peer network element.

23. The network element of claim 21, wherein the aggregate state of the links can further be standby or down, wherein the standby links are up but not transmitting traffic of the link aggregation group, and wherein down links do not carry traffic.

24. The network element of claim 21, wherein the link aggregation group further comprises a policy controller configured to place a policy to determine the aggregate state of the links coupled to the network element.

25. The network element of claim 21, wherein the event handler is further configured to forward the switched traffic based on matching an IP address prefix of one of a static route and a route learned dynamically through a protocol exchange.

26. The network element of claim 21, wherein the confirmation is sent by the peer network element, and the peer network element performs:

activating links of the link aggregation group coupled to the peer network element after receiving the notification about the anomaly; and

sending the activation confirmation to the network element after activation of the links of the link aggregation group completes.

27. The network element of claim 21, wherein detecting the anomaly of active links of the link aggregation group is based on a threshold number of links of the active links malfunctioning.

28. The network element of claim 27, wherein the threshold number of links of the active links for detecting the anomaly is configurable.

29. The network element of claim 21, wherein determining the network element being active is performed through a protocol exchange with the peer network element of the link aggregation group.

30. The network element of claim 29, wherein the protocol exchange complies with an implementation of inter-chassis control protocol (ICCP), and wherein the protocol exchange is performed through the inter-peer link.

31. A network element communicatively coupled with aggregation ports through links of a link aggregation group, wherein the link aggregation group contains a local interface and a remote interface, wherein the local interface is a logical interface formed by a plurality of network elements, wherein the logical interface includes the network element and a peer network element, wherein the remote interface is at a remote network element coupled to the link aggregation group through links of the link aggregation group, wherein the network element communicates with the peer network element through an inter-peer link, the network element comprising:

a storage device configured to store a forwarding information base (FIB), wherein the FIB contains forwarding information to aid the network element to forward traffic; and

a link aggregation group processor, including;

a link state checker configured to determine that the network element is active or standby by checking that an aggregate state of the links coupled to the network element is active or standby, wherein the aggregate state of the links being active indicates that a number of the links are up and transmitting traffic of the link aggregation group, and wherein the aggregate state of the links being standby indicates that a number of the links are up but not transmitting traffic of the link aggregation group; and

a route controller configured to set a primary next-hop interface address of the network element to be an IP address belonging to a subnet of the link aggregation group and to set a backup next-hop interface address of the network element to be an IP address of the peer network element in the FIB upon the link state checker determines the network element being active;

the route controller further configured to set the primary next-hop interface address of the network element to be IP address of the peer network element and set the backup next-hop interface address of the network element to be the IP address belonging to the subnet of the link aggregation group in the FIB upon the link state checker determines that the network element being standby.

32. The network element of claim 31, wherein determining the network element being active or standby further includes determining the peer network element being active or standby.

33. The network element of claim 31, wherein the aggregate state of the links further includes down, wherein down links do not carry traffic, and wherein no setting of next-hop interface address at the network element coupled to the down links is performed.

34. The network element of claim 31, wherein the link aggregation group processor further comprises a policy controller, the policy controller being configured to determine the aggregate state of the links coupled to the network element.

35. The network element of claim 31, wherein the route controller is further configured to set an IP subnet prefix for the local interface.

36. The network element of claim 35, wherein the route controller is further configured to synchronize settings to the peer network element by a protocol exchange between the network element and the peer network element, the setting including at least one of:

the IP address settings;

link aggregation states; and

the IP subnet prefix.

37. The network element of claim 31, further comprising a storage device configured to store a routing information base (RIB), wherein the RIB contains routing information to aid the network element to route traffic through an implementation of Internet Protocol (IP) using IP addresses.

38. The network element of claim 31, further comprising:

an aggregation interface configured to receive a packet; and

the route controller is further configured to send an address resolution request to resolve an address for the packet to a destination specified by the primary next-hop interface address of the network element upon determining that the primary next-hop specified by the primary next-hop interface address works properly, and

the route controller is further configured to receive a reply to the address resolution request, wherein the reply to the address resolution request helps traffic forwarder to forward the packet.

39. The network element of claim 38, further comprising:

the route controller is further configured to send the address resolution request to a destination specified by the backup next-hop interface address of the network element upon determining that the primary next-hop specified by the primary next-hop interface address does not work properly,

the route controller is further configured to receive a reply to the address resolution request, and

the route controller is further configured to receive a reply to the address resolution request, wherein the reply to the address resolution request helps traffic forwarder to forward the packet.

40. The network element of claim 38, wherein the address resolution request complies with one of an address resolution protocol (ARP) and a neighbor discovery (ND) protocol.