Configure a placeholder ISP

To test egress policies or default routes accurately, you may need to model external connectivity like the Internet or a private backbone. Create a JSON file at batfish/isp_config.json within your snapshot directory.

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Define the interfaces on your border routers that connect to the external network and define the placeholder ISP(s).

batfish/isp_config.json

{
    "borderInterfaces": [
        {
            "borderInterface": {
                "hostname": "your-border-router-hostname-1",
                "interface": "GigabitEthernet0/1"
            }
        },
        {
            "borderInterface": {
                "hostname": "your-border-router-hostname-2",
                "interface": "GigabitEthernet0/3"
            }
        }
    ],
    "ispNodeInfo": [
        {
            "asn": 64501,
            "name": "ISP1_Transit",
            "role": "TRANSIT" // Models Internet, provides default route
        },
        {
            "asn": 64502,
            "name": "ISP2_Backbone",
            "role": "PRIVATE_BACKBONE" // Models private peering, no default route
        }
    ]
}

• borderInterfaces: List the interfaces on your devices connecting externally.
• ispNodeInfo: Define each placeholder ISP with its ASN, name, and role.
  • TRANSIT: Simulates a standard Internet Service Provider, injecting a default route.
  • PRIVATE_BACKBONE: Simulates a private connection (like MPLS), does not provide a default route.

Upload the snapshot using invariant run to re-evaluate the network with external network model in place.

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See Docs > Reference > Snapshots for more details on isp_config.json structure.