# US 11,451,471 B2 · Using PCE as SDN controller

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- Number: US 11,451,471 B2
- Document ID: US11451471B2
- Status: Granted
- Kind: B2
- Application number: 17/107,670
- Filed: 2020-11-30
- Published: 2021-06-03
- Granted: 2022-09-20
- Earliest claimed: 2013-10-11
- Assignees: Futurewei Technologies, Inc.
- Applicants: Futurewei Technologies, Inc.
- Inventors: Qianglin Quintin Zhao; Katherine Zhao; Bisong Tao
- Web page: https://patentgrep.com/patent/US11451471B2

## CPC

- H04L 45/50: using label swapping, e.g. multi-protocol label switch [MPLS]
- H04L 45/028: Dynamic adaptation of the update intervals, e.g. event-triggered updates
- H04L 45/42: Centralised routing
- H04L 45/507: {Label distribution}
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

Embodiments relate generally to systems and methods for transitioning a system from a tradition network to a Software Defined Network (SDN) enabled network. In some embodiments, the systems and methods may comprise the use of a Path Computation Element (PCE) as a central controller. Smooth transition between traditional network and the new SDN enabled network, especially from a cost impact assessment perspective, may be accomplished using the existing PCE components from the current network to function as the central controller of the SDN network is one choice, which not only achieves the goal of having a centralized controller to provide the functionalities needed for the central controller, but also leverages the existing PCE network components.

## Claims

### Claim 1

A method for using a path computation element (PCE) as a central controller in a network, the method comprising:
receiving, by the PCE, a path computation request from a path computation client (PCC), the path computation request requesting computation for a path from a head end node to a tail end node;
computing, by the PCE, the path from the head end node to the tail end node in response to the path computation request, wherein the calculated path comprises a plurality of nodes;
allocating, by the PCE, a first node segment identity (ID) for a first node of the plurality nodes, wherein the first node segment ID is associated with a global label range;
allocating, by the PCE, a second node segment ID for a second node of the plurality nodes, wherein the second node segment ID is associated with the global label range;
sending, by the PCE, the first node segment ID to the head end node; and
sending, the second node segment ID to the head end node, wherein the second segment ID is sent along with the first node segment ID in a label stack.

### Claim 2 (depends on 1)

The method of claim 1, wherein the global label range is negotiated.

### Claim 3

A method for using a path computation element (PCE) as a central controller in a network, the method comprising:
receiving, by the PCE, a path computation request from a path computation client (PCC), the path computation request requesting computation for a path from a head end node to a tail end node;
computing, by the PCE, the path from the head end node to the tail end node in response to the path computation request, wherein the calculated path comprises a plurality of nodes;
allocating, by the PCE, adjacency segment IDs for each link between the plurality of nodes, wherein each adjacency segment ID is associated with a local label range or a global label range; and
sending, by the PCE, the adjacency segment IDs to the headend node,
wherein the adjacency segment IDs are sent as a label stack.

### Claim 4

A Path Computation Element (PCE) as a central controller in a network, the PCE comprising:
a receiver configured to receive a path computation request from a path computation client (PCC), the path computation request requesting computation for a path from a head end node to a tail end node;
a processor, coupled to the receiver, configured to compute the path from the head end node to the tail end node in response to the path computation request, wherein the calculated path comprises a plurality of nodes;
allocate a first node segment identity (ID) for a first node of the plurality nodes, wherein the first node segment ID is associated with a global label range; and
allocate a second node segment ID for a second node of the plurality nodes, wherein the second node segment ID is associated with the global label range;
and
a transmitter coupled to the processor and configured to:
send the first node segment ID to the head end node;
send the second node segment ID to the head end node, wherein the second segment ID is sent along with the first node segment ID in a label stack.

### Claim 5 (depends on 4)

The PCE of claim 4, wherein the global label range is negotiated.

### Claim 6

A Path Computation Element (PCE) as a central controller in a network, the PCE comprising:
a receiver configured to receive a path computation request from a path computation client (PCC), the path computation request requesting computation for a path from a head end node to a tail end node;
a processor, coupled to the receiver, configured to compute the path from the head end node to the tail end node in response to the path computation request, wherein the calculated path comprises a plurality of nodes;
allocate a first node segment identity (ID) for a first node of the plurality nodes, wherein the first node segment ID is associated with a global label range; and
allocate an adjacency segment ID for a link between the first node and a next-hop node of the first node, and wherein the adjacency segment ID is associated with a local label range or the global label range
and
a transmitter coupled to the processor and configured to:
send the first node segment ID to the head end node.

### Claim 7

A Path Computation Element (PCE) as a central controller in a network, the PCE comprising:
a receiver configured to receive a path computation request from a path computation client (PCC), the path computation request requesting computation for a path from a head end node to a tail end node;
a processor coupled to the receiver and configured to:
compute the path from the head end node to the tail end node in response to the path computation request, wherein the calculated path comprises a plurality of nodes; and
allocate adjacency segment IDs for each link between the plurality of nodes, wherein each adjacency segment ID is associated with a local label range or a global label range;
and
a transmitter coupled to the processor and configured to:
send the adjacency segment IDs to the headend node,
wherein the adjacency segment IDs are sent as a label stack.

### Claim 8

A method for using a path computation element (PCE) as a central controller in a network, the method comprising:
receiving, by the PCE, a path computation request from a path computation client (PCC), the path computation request requesting computation for a path from a head end node to a tail end node;
computing, by the PCE, the path from the head end node to the tail end node in response to the path computation request, wherein the calculated path comprises a plurality of nodes;
allocating, by the PCE, a first node segment identity (ID) for a first node of the plurality nodes, wherein the first node segment ID is associated with a global label range;
sending, by the PCE, the first node segment ID to the head end node; and
allocating, an adjacency segment ID for a link between the first node and a next-hop node of the first node, wherein the adjacency segment ID is associated with a local label range or the global label range.

### Claim 9 (depends on 8)

The method of claim 8, wherein the global label range is negotiated.

### Claim 10 (depends on 8)

The method of claim 8, further comprising:
sending, by the PCE, the adjacency segment ID to the head end node, wherein the second segment ID is sent along with the first node segment ID in a label stack.

### Claim 11

A Path Computation Element (PCE) as a central controller in a network, the PCE comprising:
a receiver configured to receive a path computation request from a path computation client (PCC), the path computation request requesting computation for a path from a head end node to a tail end node;
a processor coupled to the receiver configured to compute the path from the head end node to the tail end node in response to the path computation request, wherein the calculated path comprises a plurality of nodes;
allocate a first node segment identity (ID) for a first node of the plurality nodes, wherein the first node segment ID is associated with a global label range; and
allocate an adjacency segment ID for a link between the first node and a next-hop node of the first node, and wherein the adjacency segment ID is associated with a local label range or the global label range, and
a transmitter coupled to the processor and configured to:
send the first node segment ID to the head end node.

### Claim 12 (depends on 11)

The PCE of claim 11, wherein the global label range is negotiated.

### Claim 13 (depends on 11)

The PCE of claim 11, wherein the transmitter is further configured to send the adjacency segment ID to the head end node, wherein the second segment ID is sent along with the first node segment ID in a label stack.