CORE connecting to multiple COREs at an IXP

note

An Anapaya CORE appliance is a SCION-speaking router that is part of a SCION AS. A single AS is typically made up of several CORE appliances. The AS that the appliance belongs to is part of one or more isolation domains (ISDs) and can hold the core role in some of them while being non-core in others. The core role is a SCION network role and is not the same as the Anapaya CORE product. For more information, see What is the core role?.

This particular guide configures a core AS, because an AS must be a core AS to establish a SCION link to an AS in a different ISD.

In this example, configure the CORE appliance of ISP 1 to connect to two other CORE appliances of ISP 2 and ISP 3 using two SCION links. The SCION links use the physical network of the IXP as the underlay network and thus have the same IP address, but different UDP ports as shown in the figure below.

Configure the following:

1. The physical network interface that is used to connect to the IXP's network in the interfaces section of the configuration.
2. The CORE SCION links to ISP 2 and ISP 3 in the scion.ases.neighbors section of the configuration.

The relevant parts of the configuration for the CORE appliance of ISP 1 are shown below.

Example: Network interface

{
  "interfaces": {
    "ethernets": [
      {
        "name": "eth0",
        "addresses": ["192.168.1.10/24"],
      },
    ]
  }
}

Example: SCION links

{
  "scion": {
    "ases": [
      {
        "isd_as": "1-ff00:0:1",
        "neighbors": [
          {
            "neighbor_isd_as": "1-ff00:1:1",
            "relationship": "CORE",
            "interfaces": [
              {
                "address": "192.168.1.10:31000",
                "administrative_state": "UP",
                "interface_id": 10,
                "scion_mtu": 1472,
                "remote": {
                  "address": "192.168.1.20:31000",
                  "interface_id": 100
                }
              }
            ]
          },
          {
            "neighbor_isd_as": "1-ff00:2:1",
            "relationship": "CORE",
            "interfaces": [
              {
                "address": "192.168.1.10:31001",
                "administrative_state": "UP",
                "interface_id": 20,
                "scion_mtu": 1472,
                "remote": {
                  "address": "192.168.1.30:31000",
                  "interface_id": 15
                }
              }
            ]
          }
        ]
      }
    ]
  }
}