Establishing label switched paths having refresh interval independent fast reroute facility protection
In one example, techniques of this disclosure may enable a point of local repair (PLR) network device to signal availability of link protection or node protection to a merge point (MP) network device and enable a network device to actively determine whether or not it is a merge point router. Based on whether or not the network device determines it is a MP, the network device may selectively clean up LSP states when there is an upstream link or node failure. The RSVP-TE protocol may be extended to enable a network device to send a tear down message to a downstream router, which may enable the downstream router to conditionally delete locale LSP state information. In some instances, a PLR network device may directly send a tear down message to a MP network device even though the PLR network device may not have a working bypass LSP.
1. A method comprising:
receiving, with a first network device and from a second network device, a first resource reservation path message for establishing a label switched path between the second network device and a third network device, wherein the first resource reservation path message specifies whether local protection is desired for the label switched path; and
responsive to determining that the first resource reservation request message specifies that local protection is desired and responsive to receiving a resource reservation response message from a next hop network device toward the third network device:
establishing, by the first network device, a bypass label switched path between the first network device and a merge point network device along the label switched path; and
sending, by the first network device and to the next hop network device along the label switched path, a second resource reservation path message.
2. The method of claim 1 , wherein the first resource reservation path message further specifies whether node protection is desired, wherein the merge point network device is a first merge point network device, wherein the bypass label switched path between the first network device and the first merge point network device is a first bypass label switched path, and wherein the first bypass label switched path bypasses a protected network link positioned between the first network device and the first merge point network device, the method further comprising:
responsive to determining that the first resource reservation request message specifies that local protection and node protection is desired:
establishing, by the first network device, a second bypass label switched path between the first network device and a second merge point network device, wherein the second bypass label switched path bypasses a protected network device positioned between the first network device and the second merge point network device; and
generating, by the first network device, the second resource reservation path message specifying that node protection is available.
3. The method of claim 1 , wherein the first resource reservation path message includes a local protection flag, and wherein the first resource reservation path message specifies that local protection is desired when the local protection flag is set.
4. The method of claim 1 , wherein the second resource reservation path message that specifies local protection is available by at least including a protection availability flag that is set.
5. The method of claim 1 , further comprising:
sending, by the first network device, a remote resource reservation hello message, wherein a destination address of the remote resource reservation hello message is an address of the merge point network device, wherein the merge point network device is a next next hop of the first network device; and
receiving, by the first network device and from the merge point network device, a remote resource reservation hello message ack message sent in response to the remote resource reservation hello message.
6. The method of claim 1 , wherein the first resource reservation path message includes an enhanced facility protection flag, and wherein the resource reservation response message is a first resource reservation response message, the method further comprising:
determining, by the first network device and based at least in part on the enhanced facility protection flag of the first resource reservation path message, whether the second network device supports enhanced facility protection;
responsive to determining, by the first network device, that the second network device does not support enhanced facility protection, generating, by the first network device, a second resource reservation response message that specifies a refresh time value that is smaller than if the second network device did support enhanced facility protection; and
sending, from the first network device to the second network device, the resource reservation response message.
7. The method of claim 1 , wherein the resource reservation response message is a first resource reservation response message, the method further comprising:
receiving, by the first network device, from the next hop next device, a second resource reservation response message that includes an enhanced facility protection flag;
determining, by the first network device and based at least in part on the enhanced facility protection flag of the second resource reservation response message, whether the next hop network device supports enhanced facility protection;
responsive to determining, by a first network device, that the next hop network device does not support enhanced facility protection fast reroute, generating, by the first network device, a third resource reservation path message that specifies a refresh time value that is smaller than if the second network device did support enhanced facility protection fast reroute; and
sending, from the first network device to the next hop network device, the third resource reservation path message.
8. The method of claim 1 , wherein the resource reservation response message is a first resource reservation response message, the method further comprising:
receiving, by the first network device, from the second network device, a resource reservation hello message that includes an enhanced facility protection flag;
determining, by the first network device and based at least in part on the enhanced facility protection flag of the first resource reservation hello message, whether the second network device supports enhanced facility protection;
responsive to determining, by a first network device, that the second network device does not support enhanced facility protection fast reroute, generating, by the first network device, a second resource reservation response message that specifies a refresh time value that is smaller than if the second network device did support enhanced facility protection fast reroute; and
sending, from the first network device to the second network device, the second resource reservation response message.
9. The method of claim 1 , wherein the resource reservation response message is a first resource reservation response message, the method further comprising:
receiving, by the first network device, from the next hop network device, a resource reservation hello message that includes an enhanced facility protection flag;
determining, by the first network device and based at least in part on the enhanced facility protection flag of the resource reservation hello message, whether the second network device supports enhanced facility protection; and
responsive to determining, by a first network device, that the next hop network device does not support enhanced facility protection fast reroute, generating, by the first network device, the second resource reservation path message such that the second resource reservation path messages specifies a refresh time value that is smaller than if the next hop network device did support enhanced facility protection fast reroute.
10. The method of claim 1 , wherein the first resource reservation path message specifies a refresh interval of at least one minute.
11. The method of claim 1 , wherein the first resource reservation path message further specifies whether node protection is desired, wherein the merge point network device is a first merge point network device, wherein the bypass label switched path between the first network device and the first merge point network device is a first bypass label switched path, and wherein the first bypass label switched path bypasses a protected network link positioned between the first network device and the first merge point network device, the method further comprising:
responsive to determining that the first resource reservation request message specifies that local protection is desired and that node protection is not desired:
establishing, by the first network device, a second bypass label switched path between the first network device and a second merge point network device, wherein the second bypass label switched path bypasses a protected network link positioned between the first network device and the second merge point network device; and
generating, by the first network device, the second resource reservation path message specifying that link protection is available.
12. A first network device comprising:
one or more network interface cards; and
a control unit configured to:
receive, from a second network device using at least one of the one or more network interface cards, a first resource reservation path message for establishing a label switched path between the second network device and a third network device, wherein the first resource reservation request message specifies whether local protection is desired for the label switched path; and
responsive to determining that the first resource reservation request message specifies that local protection is desired and responsive to receiving a resource reservation response message from the next hop network device:
establish a bypass label switched path between the first network device and a merge point network device along the label switched path; and
send, to the next hop network device along the label switched path using at least one of the one or more network interface cards, a second resource reservation path message that specifies that local protection has been established for the label switched path at the first network device.
13. The first network device of claim 12 ,
wherein the first resource reservation path message further specifies whether node protection is desired,
wherein the merge point network device is a first merge point network device,
wherein the bypass label switched path between the first network device and the first merge point network device is a first bypass label switched path,
wherein the first bypass label switched path bypasses a protected network link positioned between the first network device and the merge point network device, and
wherein the control unit is further configured to:
responsive to determining that the first resource reservation request message specifies that local protection and node protection is desired:
establish a second bypass label switched path between the first network device and a second merge point network device, wherein the second bypass label switched path bypasses a protected network device positioned between the first network device and the merge point network device; and
generate the second resource reservation path message specifying that node protection is available; and
responsive to determining that the first resource reservation request message specifies that local protection is desired and that node protection is not desired:
establish the second bypass label switched path between the first network device and the second merge point network device, wherein the second bypass label switched path bypasses a protected network link positioned between the first network device and the second merge point network device; and
generate the second resource reservation path message specifying that link protection is available.
14. The first network device of claim 13 , wherein the first resource reservation path message includes a local protection flag and a node protection flag, wherein the first resource reservation path message specifies that local protection is desired when the local protection flag is set, and wherein the first resource reservation path message specifies that node protection is desired when the node protection flag is set.
15. The first network device of claim 12 , wherein the first resource reservation path message includes a local protection flag, and wherein the first resource reservation path message specifies that local protection is desired when the local protection flag is set.
16. The first network device of claim 12 , wherein the second resource reservation path message that specifies local protection is available by at least including a protection availability flag that is set.
17. The first network device of claim 12 , wherein the control unit is configured to send, using at least one of the one or more network interface cards, a remote resource reservation hello message, wherein a destination address of the remote resource reservation hello message is an address of the merge point network device, wherein the merge point network device is a next hop of the first network device, and receive, from the merge point network device, a remote resource reservation hello message ack message sent in response to the remote resource reservation hello message.
18. The first network device of claim 12 ,
wherein the first resource reservation path message includes an enhanced facility protection flag,
wherein the resource reservation response message is a first resource reservation response message, and
wherein the control unit is configured to:
determine, based at least in part on the enhanced facility protection flag of the first resource reservation path message, whether the second network device supports enhanced facility protection;
responsive to determining that the second network device does not support enhanced facility protection, generate a second resource reservation response message that specifies a refresh time value that is smaller than if the second network device did support enhanced facility protection; and
send, to the second network device and using at least one of the one or more network interface cards, the second resource reservation response message.
19. The first network device of claim 12 ,
wherein the resource reservation response message is a first resource reservation response message, and
wherein the control unit is configured to:
receive, from the next hop next device and using at least one of the one or more network interface cards, a resource reservation response message that includes an enhanced facility protection flag;
determine, based at least in part on the enhanced facility protection flag of the first resource reservation response message, whether the next hop network device supports enhanced facility protection;
responsive to determining that the next hop network device does not support enhanced facility protection fast reroute, generate a second resource reservation path message that specifies a refresh time value that is smaller than if the second network device did support enhanced facility protection fast reroute; and
send, to the next hop network device and using at least one of the one or more network interface cards, the second resource reservation path message.
20. The first network device of claim 12 ,
wherein the resource reservation path message is a first resource reservation path message, and
wherein the control unit is configured to:
receive, from the second network device and using at least one of the one or more network interface cards, a resource reservation hello message that includes an enhanced facility protection flag;
determine, based at least in part on the enhanced facility protection flag of the resource reservation hello message, whether the second network device supports enhanced facility protection;
responsive to determining, by a first network device, that the second network device does not support enhanced facility protection fast reroute, generate a second resource reservation response message that specifies a refresh time value that is smaller than if the second network device did support enhanced facility protection fast reroute; and
send, to the second network device and using at least one of the one or more network interface cards, the second resource reservation response message.