Describe the bug
Even if there is a notation error in yaml, it will be displayed as a file open error.

https://github.com/nttcom/pola/blob/e287c3f6e90e44b3de8cc545b5a7cbeb04fea289/cmd/pola/sr_policy_add.go#LL45C21-L45C21

Create spec.yaml for PCE using BGP-LS in "pola/examples".
Leave the existing "pola/examples/sr-mpls_l3vpn/" as a TED disable example.

Add tests for gRPC Server

Currently TED only supports IPv4 underlay.
Allow IPv6 underlay information to be stored as well.

https://github.com/nttcom/pola/blob/main/internal/pkg/table/ted.go

Description

• Add uSID path calculation in Pola PCE

Motivation and Context

• Add SR Policy using uSID
• Achieve interoperability with IOS-XR

Prerequisite

• Required to get uSID from BGP-LS

• https://tex2e.github.io/rfc-translater/html/rfc5440.html

• Update proto file pola.proto
• Add command pola ted [-j]

Define the data structure of TED.
https://tex2e.github.io/rfc-translater/html/rfc7752.html

Is your feature request related to a problem? Please describe.
Pola PCE can't remove LSP (SR Policy) using available functions.

Describe the solution you'd like
Add gRPC interface and update PCEP library for LSP deletion.

Additional context
reference: https://www.rfc-editor.org/rfc/rfc8231.html#section-7.3

Implement the following functions

• If TED is nil, do not calculate the route and return an error
• Output to log that TED does not exist

Currently PCEP library only supports IPv4 underlay.
Enable PCEP library to handle IPv6 underlay as well.

https://github.com/nttcom/pola/tree/main/pkg/packet/pcep

Sample format

{
    "peers": [
        {
            "peerAddr": "192.0.2.1",
            "lsps": [
                {
                    "policyName": "sample_policy1",
                    "srcAddr": "192.0.2.1",
                    "dstAddr": "192.0.2.2",
                    "segmentlist": [
                        16003,
                        16002
                    ]
                },
                {
                    "policyName": "sample_policy2",
                    "srcAddr": "192.0.2.1",
                    "dstAddr": "192.0.2.2",
                    "segmentlist": [
                        16003,
                        16001,
                        16002
                    ]
                },
            ]
        },
        {
            "peerAddr": "192.0.2.2",
            "lsps": [
                {
                    "policyName": "sample_policy3",
                    "srcAddr": "192.0.2.2",
                    "dstAddr": "192.0.2.1",
                    "segmentlist": [
                        16003,
                        16001
                    ]
                },
                {
                    "policyName": "sample_policy4",
                    "srcAddr": "192.0.2.2",
                    "dstAddr": "192.0.2.1",
                    "segmentlist": [
                        16003,
                        16002,
                        16001
                    ]
                },
            ]
        },       
]

• Add GoBGP's Native BGP Library implementation in polad.

Packet format

• https://tex2e.github.io/rfc-translater/html/rfc5440.html

Description

• Add Flex-Algo path calculation

Motivation and Context

• Add SR Policy using Flex-Algo SID

Prerequisite

• Required to get FAD/EAG from BGP-LS

Currently goBGP interface only supports IPv4 Link State.
Allow IPv6 Link State to be stored as well.

https://github.com/nttcom/pola/blob/main/internal/pkg/gobgp/interface.go

Enable to check capabilities per session with pola command.
relates to #41

Ex.

user@pce:~/pola/cmd/pola$ go run . session
sessionAddr(0): 10.100.0.1
  Capabilities: Stateful, Update, Segment-Routing, Instantiation
sessionAddr(1): 10.100.0.2
  Capabilities: Stateful, Update, Segment-Routing, Instantiation

reference

• pola/pkg/packet/pcep/pcep.go

  Line 294 in 1e91a39

  // OPEN Object (RFC5440 7.3)

• https://tex2e.github.io/rfc-translater/html/rfc5440.html

• Calculate path by IGP/TE/Delay metric Using TED information
• Minimize Segment-List length when calculating SR Policy path

• Investigate whether GoBGP implements gRPC's Server-streaming feature
  • https://github.com/osrg/gobgp/tree/master/api
• Implement the ability to hook BGP update to update the Pola's TED

• Add GoBGP gRPC Client
  • https://github.com/osrg/gobgp/blob/2117125f0dc41671fdfc069b953059f568010ea5/api/gobgp_grpc.pb.go#L368-L381
• Import BGP-LS info. to Pola PCE's TED