Method and Apparatus Providing Delayed Path Calculations Based on Service Type

1. A computer-implemented method in which a computer system performs operations comprising: sending, by a first network device to at least one of a plurality of other network devices in a network, link state information directing receivers of said link state information, when computing routes transiting though said first network device, to refrain from using said first network device on at least one of the group consisting of per Network Layer Protocol Identifier (NLPID), per address family, and per service within an address family; wherein said link state information comprises a Type Length Value (TLV) that is flooded to all devices in said network; wherein calculation of routes through said first network device are delayed as long as said TLV value indicates that routes should not be calculated through said first network device; and wherein said TLV indicates to other network devices not to use said first network device for Layer 2 (L2) routing but said first network device can be used for L3 routing.

2. The method of claim 1 wherein said TLV contains at least one sub-TLV to provide control of said route calculations.

3. The method of claim 1 further comprising withdrawing link state information to at least one of said other network devices to use said first network device in route calculations.

4. The method of claim 3 wherein said link state information comprises a Type Length Value (TLV) that is withdrawn and flooded to all devices in said network.

5. The method of claim 4 further comprising said at least one of said other network device updating a routing table to indicate said first network device is available for routing calculations.

6. A non-transitory computer readable storage medium having computer readable code thereon for providing delayed path calculations based on service type, the medium including instructions in which a computer system performs operations comprising: sending, by a first network device to at least one of a plurality of other network devices in a network, link state information directing receivers of said link state information, when computing routes transiting though said first network device, to refrain from using said first network device on at least one of the group consisting of per Network Layer Protocol Identifier (NLPID), per address family, and per service within an address family; wherein said link state information comprises a Type Length Value (TLV) that is flooded to all devices in said network; wherein calculation of routes through said first network device are delayed as long as said TLV value indicates that routes should not be calculated through said first network device; and wherein said TLV indicates to other network devices not to use said first network device for Layer 2 (L2) routing but said first network device can be used for L3 routing.

7. The non-transitory computer readable storage medium of claim 6 further comprising instructions wherein said TLV contains at least one sub-TLV to provide control of said route calculations.

8. The non-transitory computer readable storage medium of claim 6 further comprising instructions for withdrawing link state information to at least one of said other network devices to use said first network device in route calculations.

9. The non-transitory computer readable storage medium of claim 8 further comprising instructions wherein said link state information comprises a Type Length Value (TLV) that is withdrawn and flooded to all devices in said network.

10. The non-transitory computer readable storage medium of claim 9 further comprising instructions wherein said at least one of said other network device updating a routing table to indicate said first network device is available for routing calculations.

11. A network device comprising: a memory; a processor; a communications interface; an interconnection mechanism coupling the memory, the processor and the communications interface; and wherein the memory is encoded with an application providing delayed path calculations based on service type, that when performed on the processor, provides a process for processing information, the process causing the network device to perform the operations of: sending, by said network device to at least one of a plurality of other network devices in a network, link state information directing receivers of said link state information, when computing routes transiting though said first network device, to refrain from using said first network device on at least one of the group consisting of per Network Layer Protocol Identifier (NLPID), per address family, and per service within an address family; wherein said link state information comprises a Type Length Value (TLV) that is flooded to all devices in said network; wherein calculation of routes through said first network device are delayed as long as said TLV value indicates that routes should not be calculated through said first network device; and wherein said TLV indicates to other network devices not to use said first network device for Layer 2 (L2) routing but said first network device can be used for L3 routing.

12. The network device of claim 11 wherein said TLV contains at least one sub-TLV to provide control of said route calculations.

13. The network device of claim 11 further comprising withdrawing link state information to at least one of said other network devices to use said first network device in route calculations.

14. The network device of claim 13 wherein said link state information comprises a Type Length Value (TLV) that is withdrawn and flooded to all devices in said network.

15. The method of claim 1 wherein when L2 information is synchronized, said first network device withdraws said TLV such that other nodes can now use said network device for L2 and Layer 3 (L3) routing.

16. The computer readable storage medium of claim 6 wherein when L2 information is synchronized, said first network device withdraws said TLV such that other nodes can now use said network device for L2 and Layer 3 (L3) routing.

17. The network device of claim 11 wherein when L2 information is synchronized, said first network device withdraws said TLV such that other nodes can now use said network device for L2 and Layer 3 (L3) routing.