Hierarchical label distribution protocol for computer networks
First Claim
1. A method comprising:
- receiving a label mapping message at an ingress router within a first routing domain of a network for establishing an inter-routing domain label switched path (LSP), wherein the label mapping message identifies within a first portion of the label mapping message a first label to be used for forwarding network traffic to an intermediate router of the LSP, and identifies within a second portion of the label mapping message a second label to be used for forwarding network traffic to an egress router of the LSP within a second routing domain of the network;
parsing the first portion and the second portion of the label mapping message to identify the first label and the second label;
installing first forwarding state at the ingress router identifying the first label to be used for forwarding network traffic to the intermediate router; and
installing second forwarding state at the ingress router identifying a two-label stack to be used for forwarding network traffic on the inter-routing domain LSP to the egress router, the two-label stack comprising the first label as an outer label and the second label as an inner label.
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Abstract
Techniques are described for providing routing scalability within a protocol such as a label distribution protocol. A method comprises receiving a label mapping message at an ingress router for establishing a label switched path (LSP) that identifies within a first portion a first label to be used for forwarding network traffic to an intermediate router of the LSP, and identifies within a separate portion a second label to be used for forwarding network traffic to an egress router of the LSP. The method further comprises parsing the first and separate portions, installing first forwarding state at the ingress router identifying the first label for forwarding network traffic to the intermediate router, and installing second forwarding state at the ingress router identifying a two-label stack comprising the first label as an outer label and the second label as an inner label for forwarding network traffic to the egress router.
154 Citations
35 Claims
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1. A method comprising:
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receiving a label mapping message at an ingress router within a first routing domain of a network for establishing an inter-routing domain label switched path (LSP), wherein the label mapping message identifies within a first portion of the label mapping message a first label to be used for forwarding network traffic to an intermediate router of the LSP, and identifies within a second portion of the label mapping message a second label to be used for forwarding network traffic to an egress router of the LSP within a second routing domain of the network; parsing the first portion and the second portion of the label mapping message to identify the first label and the second label; installing first forwarding state at the ingress router identifying the first label to be used for forwarding network traffic to the intermediate router; and installing second forwarding state at the ingress router identifying a two-label stack to be used for forwarding network traffic on the inter-routing domain LSP to the egress router, the two-label stack comprising the first label as an outer label and the second label as an inner label. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for distributing labels for establishing an inter-domain label switched path (LSP) for forwarding network traffic, comprising:
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executing a routing protocol to maintain routing information for a first routing domain of a network partitioned into a plurality of routing domains; receiving a label mapping message at a border router of the first routing domain, the label mapping message identifying a first label to be used for forwarding network traffic to a first egress router within a second one of the routing domains of a network; with the border router, allocating a second label to advertise to neighboring routers in the first routing domain to be used for forwarding network traffic to the first egress router; with the border router, allocating a third label to advertise to neighboring routers the first routing domain to be used for forwarding network traffic to the border router; generating a second label mapping message that includes at least both;
(i) a required portion of the second label mapping message identifying the third label to be used for forwarding network traffic to the border router, and (ii) a separate optional portion identifying the second label to be used for forwarding network traffic to the first egress router; andadvertising the second label mapping message to one or more neighboring routers within the first routing domain of the network. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A router comprising:
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an interface configured to receive a label mapping message at an ingress router within a first routing domain of a network for establishing an inter-routing domain label switched path (LSP), wherein the label mapping message identifies within a first portion of the label mapping message a first label to be used for forwarding network traffic to an intermediate router of the LSP, and identifies within a second portion of the label mapping message a second label to be used for forwarding network traffic to an egress router of the LSP within a second routing domain of the network; a control unit configured to the first portion and the second portion of the label mapping message to identify the first label and the second label; and forwarding information that associates network destinations with specific next hops and corresponding interfaces, wherein the control unit is configured to install first forwarding state to the forwarding information identifying the first label to be used for forwarding network traffic to the intermediate router, and wherein the control unit is configured to install second forwarding state to the forwarding information identifying a two-label stack to be used for forwarding network traffic on the inter-routing domain LSP to the egress router, the two-label stack comprising the first label as an outer label and the second label as an inner label. - View Dependent Claims (23, 24, 25, 26)
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27. A non-transitory computer-readable medium comprising instructions for causing a programmable processor to:
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receive a label mapping message at an ingress router within a first routing domain of a network for establishing an inter-routing domain label switched path (LSP), wherein the label mapping message identifies within a first portion of the label mapping message a first label to be used for forwarding network traffic to an intermediate router of the LSP, and identifies within a second portion of the label mapping message a second label to be used for forwarding network traffic to an egress router of the LSP within a second routing domain of the network; parse the first portion and the second portion of the label mapping message to identify the first label and the second label; install first forwarding state at the ingress router identifying the first label to be used for forwarding network traffic to the intermediate router; and install second forwarding state at the ingress router identifying a two-label stack to be used for forwarding network traffic on the inter-routing domain LSP to the egress router, the two-label stack comprising the first label as an outer label and the second label as an inner label.
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28. A network system comprising:
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a computer network comprising a plurality of label switching routers, the label switching routers executing a routing protocol that partitions the computer network into a plurality of routing domains, each of the label switching routers maintaining routing information containing full network addresses for the routing domain in which the respective label switching router resides, the label switching routers executing a label distribution protocol to establish a label switched path that spans at least two of the routing domains, the label distribution protocol for at least one of the label switching routers requiring that network addresses advertised by label mapping messages of the label distribution protocol match the full network addresses of the routing information, and at least a first one of the label switching routers in one of the routing domains outputting one of the label mapping messages to include at least;
(i) a first Multi-protocol Label Switching (MPLS) label and a full network address for reaching the first one of the label switching routers, and (ii) one or more additional pairs of MPLS labels and corresponding network addresses for reaching network destinations within the other routing domains. - View Dependent Claims (29, 30, 31, 32, 33)
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34. A method for distributing labels for establishing an inter-area label switched path (LSP) for forwarding network traffic, comprising:
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executing, on a first label switching router, a routing protocol to maintain routing information for a first routing domain of a network partitioned into a plurality of routing domains; and outputting a label mapping message to include at least;
(i) a first Multi-protocol Label Switching (MPLS) label and a full network address of the first label switching router, and (ii) one or more additional pairs of MPLS labels and corresponding network addresses for reaching for reaching label switching routers in other the routing domains of the network,the additional pairs of MPLS labels and corresponding network addresses encoded as one or more sub-fields of the label mapping message, the sub-fields being arranged in a tree-like hierarchical order from one or more parent sub-fields to one or more child sub-fields, and each network address specified by any sub-field within the tree-like hierarchical order being reachable using a label stack comprising the first MPLS label and those MPLS labels defined by sub-fields arranged in the tree-like hierarchical order between one of the parent sub-fields and the child sub-field containing the network address to be reached.
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35. A method comprising:
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receiving a label mapping message at an ingress router within a first routing domain of a network for establishing an inter-routing domain label switched path (LSP), wherein the label mapping message identifies within a first portion of the label mapping message a first label to be used for forwarding network traffic to an intermediate router of the LSP, and identifies within a second portion of the label mapping message a second label to be used for forwarding network traffic to an egress router of the LSP within a second routing domain of the network; parsing the first portion and the second portion of the label mapping message to identify the first label and the second label; and presenting information relating to the LSP to a user, wherein the information includes the first label and the second label.
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Specification