Dual-homing layer 2 switch

Abstract

One embodiment relates to a method of providing dual-homing in a layer 2 switch. A determination is made as to whether a link is available to an upstream network on for a currently active port. If the link is unavailable, then the layer 2 switch a) performs a switchover such that the currently active port becomes a newly passive port, and a currently passive port becomes a newly active port, b) clears entries in an address table of the layer 2 switch, and c) spoofs MAC addresses out of the newly active link. Other embodiments are also disclosed.

What is claimed is: 
     
       1. A method of providing dual-homing in a layer 2 switch, the method comprising:
 determining whether a link is available to an upstream network on a currently active port; and 
 if the link is unavailable, then a) performing a switchover such that the currently active port becomes a newly passive port, and a currently passive port becomes a newly active port, b) clearing entries in an address table of the layer 2 switch, and c) spoofing MAC addresses out of the newly active port, wherein spoofing MAC addresses out of the newly active port comprises sending broadcast or multicast packets out of the newly active port and formatting the packets such that addresses of the downstream nodes are adopted as MAC addresses of the packets, wherein the packets are configured to instruct upstream devices that packets directed to the addresses of the downstream nodes should be sent to the newly active port. 
 
     
     
       2. The method of  claim 1 , wherein the determination of whether the link is available is performed by detecting a presence or an absence of an ethernet link signal. 
     
     
       3. The method of  claim 1 , wherein the determination of whether the link is available is performed by detecting a presence or an absence of a heartbeat type signal. 
     
     
       4. The method of  claim 1 , wherein the determination of whether the link is available is performed by detecting a presence or an absence of traffic through the link. 
     
     
       5. The method of  claim 1 , wherein the switchover is performed by setting the currently active port to drop traffic and by setting the currently passive port to not drop traffic. 
     
     
       6. The method of  claim 1 , wherein the switchover is performed by dropping a link signal on the currently active port and by turning on the link signal on the currently passive port. 
     
     
       7. The method of  claim 1 , wherein the clearing of entries in the address table is performed while moving addresses for downstream nodes coupled to the switch from being associated with the newly passive port to being associated with the newly active port. 
     
     
       8. The method of  claim 1 , wherein the clearing of entries in the address table forces the switch to re-learn addresses for downstream nodes coupled to the switch. 
     
     
       9. The method of  claim 1 , wherein said spoofing comprises copying addresses of downstream nodes coupled to the switch and sending broadcast or multicast packets out of the newly active port. 
     
     
       10. The method of  claim 1 , wherein said spoofing comprises sending a suitably coded protocol packet out of the newly active port so as to instruct the upstream network devices to learn a correct path for the addresses of the downstream nodes. 
     
     
       11. A network apparatus with layer 2 switching capabilities configured to provide dual-homing via two ports, the apparatus comprising:
 a currently active port and a newly passive port;  
 processor-executable code configured to determine whether a link is available to an upstream network on a the currently active port; and 
 processor-executable code configured, if the link is unavailable, to a) perform a switchover such that the currently active port becomes a the newly passive port, and a the currently passive port becomes a newly active port, b) clear entries in an address table of the layer 2 switch, and c) spoof MAC addresses out of the newly active port, wherein the processor-executable code is configured to spoof MAC addresses out of the newly active port by sending broadcast or multicast packets out of the newly active port and formatting the packets such that addresses of the downstream nodes are adopted as MAC addresses of the packets, wherein the packets are configured to instruct upstream devices that packets directed to the addresses of the downstream nodes should be sent to the newly active port. 
 
     
     
       12. The apparatus of  claim 11 , wherein the determination of whether the link is available is performed by detecting a presence or an absence of an ethernet link signal. 
     
     
       13. The apparatus of  claim 11 , wherein the determination of whether the link is available is performed by detecting a presence or an absence of a heartbeat type signal. 
     
     
       14. The apparatus of  claim 11 , wherein the determination of whether the link is available is performed by detecting a presence or an absence of traffic through the link. 
     
     
       15. The apparatus of  claim 11 , wherein the switchover is performed by setting the currently active port to drop traffic and by setting the currently passive port to not drop traffic. 
     
     
       16. The apparatus of  claim 11 , wherein the switchover is performed by dropping a link signal on the currently active port and by turning on the link signal on the currently passive port. 
     
     
       17. The apparatus of  claim 11 , wherein the clearing of entries in the address table is performed while moving addresses for downstream nodes coupled to the switch from being associated with the newly passive port to being associated with the newly active port. 
     
     
       18. The apparatus of  claim 11 , wherein the clearing of entries in the address table forces the switch to re-learn addresses for downstream nodes coupled to the switch. 
     
     
       19. The apparatus of  claim 11 , wherein said spoofing comprises copying addresses of downstream nodes coupled to the switch and sending broadcast or multicast packets out of the newly active port. 
     
     
       20. The apparatus of  claim 11 , wherein said spoofing comprises sending a suitably coded protocol packet out of the newly active port so as to instruct the upstream network devices to learn a correct path for the addresses of the downstream nodes. 
     
     
       21. The method of  claim 1 , wherein an entire address table of the layer 2 switch is cleared if the link to the upstream network is unavailable. 
     
     
       22. The network apparatus of  claim 11 , wherein the network apparatus comprises infrastructure equipment and does not comprise terminal equipment. 
     
     
       23. A network apparatus with layer 2 switching capabilities, the apparatus comprising:
 a currently active port and a newly passive port;   a switching device configured to:
 determine whether the link is available to an upstream network on a currently active port; and 
 if the link is unavailable, to:
 switch ports such that the currently active port becomes the newly passive port, and the currently passive port becomes the newly active port, 
 modify entries in an address table of the layer 2 switch by performing at least one of clearing the entries or moving one or more entries from the newly passive port to the newly active port, and 
 spoof MAC addresses out of the newly active port, wherein the switching device is configured to spoof MAC addresses out of the newly active port by sending broadcast or multicast packets out of the newly active port and formatting the packets such that addresses of the downstream nodes are adopted as MAC addresses of the packets, wherein the packets are configured to instruct upstream devices that packets directed to the addresses of the downstream nodes should be sent to the newly active port.  
 
   
     
     
       24. The apparatus of claim 23, wherein the determination of whether the link is available is performed by detecting a presence or an absence of an ethernet link signal.  
     
     
       25. The apparatus of claim 23, wherein the determination of whether the link is available is performed by detecting a presence or an absence of a heartbeat type signal.  
     
     
       26. The apparatus of claim 23, wherein the determination of whether the link is available is performed by detecting a presence or an absence of traffic through the link.  
     
     
       27. The apparatus of claim 23, wherein the ports are switched by setting the currently active port to drop traffic and by setting the currently passive port to not drop traffic.  
     
     
       28. The apparatus of claim 23, wherein the ports are switched by dropping a link signal on the currently active port and by turning on the link signal on the currently passive port.  
     
     
       29. The apparatus of claim 23, wherein the modifying of entries in the address table is performed while moving addresses for downstream nodes coupled to the switch from being associated with the newly passive port to being associated with the newly active port.  
     
     
       30. The apparatus of claim 23, wherein the modifying of entries in the address table forces the switch to re-learn addresses for downstream nodes coupled to the switch.  
     
     
       31. The network apparatus of claim 23, wherein the network apparatus comprises infrastructure equipment and does not comprise terminal equipment.  
     
     
       32. A network apparatus with layer 2 switching capabilities, the apparatus comprising:
 a currently active port and a newly passive port;   a switching device configured to:
 determine whether the link is available to an upstream network on a currently active port; and 
 if the link is unavailable, to:
 switch ports such that the currently active port becomes the newly passive port, and the currently passive port becomes the newly active port, 
 modify entries in an address table of the layer 2 switch by performing at least one of clearing the entries or moving one or more entries from the newly passive port to the newly active port, and 
 send packets out of the newly active port to one or more upstream devices in the upstream network, wherein the packets are formatted such that addresses of the downstream nodes are adopted as MAC addresses of the packets, and wherein the packets are configured to inform the upstream devices that packets directed to the addresses of the downstream nodes should be sent to the newly active port.  
 
   
     
     
       33. The apparatus of claim 32, wherein said sending comprises copying the addresses of the downstream nodes and sending broadcast or multicast packets out of the newly active port.  
     
     
       34. The apparatus of claim 32, wherein said sending comprises sending a suitably coded protocol packet out of the newly active port so as to instruct the upstream network devices to learn a correct path for the addresses of the downstream nodes.