Method and apparatus for achieving transparent redundancy at a hierarchical boundary
View Patent ↗Transparent redundancy may be achieved at a MPLS-MPLS hierarchical boundary or a BMA-MPLS hierarchical boundary by utilizing local repair mechanisms extant in each domain to select automatically the same boundary network devices as the primary and secondary boundary network devices. In the MPLS domain, two LERs advertise the ability to forward traffic to a phantom LER and map all traffic originated into that domain as having been on a path originating at the phantom LER. This will cause the LERs to appear as being one hop away from the phantom LER, causing MPLS to assume the real LERs are part of a LSP terminating at the phantom LER. MPLS local repair will thus establish one of the LERs as the primary LER and the other LER as the secondary LER. In an Ethernet domain, each boundary network device is treated analogously to a router in the VRRP scheme for routers.
1. A method of establishing redundant boundary network devices at a hierarchical boundary, the method comprising the steps of:
impersonating, in a first multiprotocol label switching (MPLS) domain, a first label switch router (LSR) by a first label edge router (LER); and
impersonating, in the first MPLS domain, a second LSR by a second LER;
wherein the step of impersonating the first LSR by the first LER comprises advertising an ability to forward traffic to a first phantom LER, and wherein the step of impersonating the second LSR by the second LER comprises advertising an ability to forward traffic to the first phantom LER.
2. The method of claim 1 , wherein the step of impersonating the first LSR by the first LER comprises mapping traffic originated into the MPLS domain through the first LER as being on a first path originating at the first phantom LER, and wherein the step of impersonating the second LSR by the second LER comprises mapping traffic originating into the MPLS domain through the second LER as being on a second path originating at the first phantom LER.
3. The method of claim 2 , wherein the first path is a working path and the second path is a backup path.
4. The method of claim 1 , further comprising the step of communicating, from the first LER to the second LER, information relevant to label switched paths through the first MPLS domain.
5. The method of claim 1 , wherein the step of impersonating the first LSR by the first LER further comprises establishing the first LER as having a preferred route to the first phantom LER.
6. A method of establishing redundant boundary network devices at a hierarchical boundary, the method comprising the steps of:
impersonating, in a first multiprotocol label switching (MPLS) domain, a first label switch router (LSR) by a first label edge router (LER);
impersonating, in the first MPLS domain, a second LSR by a second LER;
impersonating, in a second MPLS domain, a third LSR by a third LER; and
impersonating, in the second MPLS domain, a fourth LSR by a fourth LER.
7. The method of claim 6 , wherein the step of impersonating the third LSR by the third LER comprises advertising an ability to forward traffic to a second phantom LER, and wherein the step of impersonating the fourth LSR by the fourth LER comprises advertising an ability to forward traffic to the second phantom LER.
8. The method of claim 6 , wherein the step of impersonating the third LSR by the third LER comprises mapping traffic originated into the second MPLS domain through the third LER as being on a third path originating at a second phantom LER, and wherein the step of impersonating the fourth LSR by the fourth LER comprises mapping traffic originated into the second MPLS domain through the fourth LER as being on a fourth path originating at the second phantom LER.
9. The method of claim 8 , wherein the third path is a working path and wherein the fourth path is a backup path.
10. The method of claim 6 , further comprising the step of communicating, from the third LER to the fourth LER, information relevant to label switched paths through the second MPLS domain.
11. The method of claim 7 , wherein the step of impersonating the third LSR by the third LER further comprises establishing the third LER as having a preferred route to the second phantom LER.
12. The method of claim 1 , further comprising the step of:
establishing, in a broadcast domain, a redundancy group containing at least a first network device and a second network device.
13. The method of claim 12 , wherein the first network device is the first LER, and wherein the second network device is the second LER.
14. The method of claim 12 , wherein the first network device is a master router and wherein the second network device is a backup router.
15. The method of claim 14 , wherein the master router is hosted on a first platform, and wherein the backup router is hosted on a second platform.
16. The method of claim 15 , wherein the master router and the backup router are virtual routers.
17. The method of claim 16 , wherein the master router has state tables, and wherein the state tables of the master router are replicated to the backup router.
18. The method of claim 12 , further comprising exchanging routing information between the first network device and the second network device.
19. A redundancy group of network devices, comprising:
a first label edge router (LER) having control logic configured to impersonate, in a first multiprotocol label switching (LER) domain, a first label switch router (LSR); and
a second LER having control logic configured to impersonate, in the first MPLS domain, a second LSR;
wherein the control logic of the first LER impersonates the first LSR by advertising an ability to forward traffic to a first phantom LER, and wherein the control logic of the second LER impersonates the second LSR by advertising an ability to forward traffic to the first phantom LER.
20. The redundancy group of claim 19 , wherein the control logic of the first LER impersonates the first LSR by mapping traffic originated into the MPLS domain through the first LER as being on a first path originating at the first phantom LER, and wherein the control logic of the second LER impersonates the second LSR by mapping traffic originated into the MPLS domain through the second LER as being on a second path originating at the first phantom LER.
21. The redundancy group of claim 20 , wherein the first path is a working path and the second path is a backup path.
22. The redundancy group of claim 19 , wherein the control logic of the first LER is further configured to communicate information relevant to label switched paths through the first MPLS domain to the second LER.
23. The redundancy group of claim 19 , wherein the control logic of the first LER is further configured to establish the first LER as having a preferred route to the first phantom LER.
24. A redundancy group of network devices, comprising:
a first label edge router (LER) having control logic configured to impersonate, in a first multiprotocol label switching (MPLS) domain, a first label switch router (LSR); and
a second LER having control logic configured to impersonate, in the first MPLS domain, a second LSR;
wherein the control logic of the first LER is further configured to impersonate a third LSR in a second MPLS domain; and
wherein the control logic of the second LER is further configured to impersonate a fourth LSR in the second MPLS domain.
25. The redundancy group of claim 24 , wherein the control logic of the first LER is configured to impersonate the third LSR by advertising an ability to forward traffic to a second phantom LER, and wherein the control logic of the second LER is configured to impersonate the fourth LSR by advertising an ability to forward traffic to the second phantom LER.
26. The redundancy group of claim 24 , wherein the control logic of the first LER is configured to impersonate the third LSR by mapping traffic originated into the second MPLS domain through the third LER as being on a third path originating at a second phantom LER, and wherein the control logic of the second LER is configured to impersonate the fourth LSR by mapping traffic originated into the second MPLS domain through the fourth LER as being on a fourth path originating at the second phantom LER.
27. The redundancy group of claim 26 , wherein the third path is a working path and wherein the fourth path is a backup path.
28. The redundancy group of claim 24 , wherein the control logic of the third LER is further configured to communicate information relevant to label switched paths through the second MPLS domain to the fourth LER.
29. The redundancy group of claim 25 , wherein the control logic of the third LER is further configured to establish the third LER as having a preferred route to the second phantom LER.
30. The redundancy group of claim 19 ,
wherein the control logic of the first LER is configured to establish itself, in a broadcast domain, as a first member of a redundancy group; and
wherein the control logic of the second LER is configured to establish itself, in the broadcast domain, as a second member of the redundancy group.
31. The redundancy group of claim 30 , wherein the first member is a master router and wherein the second member is a backup router.
32. The redundancy group of claim 31 , wherein the first member and second member are virtual routers.
33. The redundancy group of claim 32 , wherein the first member has state tables, and wherein the state tables of the first member are replicated to the second member.