To establish service link connectivity, external BGP (eBGP) peering sessions are created between each OND and the CND. A /30 or /31 IP address is used as a BGP peering IP address for each BGP session between the Outposts service link autonomous system and the organization’s autonomous system using private Autonomous System Numbers (ASNs) to complete the configuration. The following diagram shows the VLANs and subnet information required to establish service link BGP connectivity:
Figure 10.9 – Service link and LGW traffic segregated using VLANs
The following table breaks down the configuration required for the service link BGP connectivity:
| VLAN | BGP | Device | LAG | BGP Subnet | OND IP | CND IP | Outposts ASN | Organization ASN |
| VLAN A | Service link BGP 1 | OND1 to CND1 | LAG 1 | 169.254.1.0/30 | 169.254.1.1/30 | 169.254.1.2/30 | 65013 | 65000 |
| Service link BGP 2 | OND2 to CND2 | LAG 2 | 169.254.3.0/30 | 169.254.3.1/30 | 169.254.3.2/30 |
Table 10.4 – Sample BGP parameters for service link connectivity
Local gateway BGP connectivity
Similar to service link connectivity, LGW connectivity is also established using eBGP peering sessions between each OND and the CND. A /30 or /31 IP address is used as the BGP peering IP address for each BGP session between the Outposts LGW autonomous system and the organization autonomous system using private ASNs to complete the configuration. The following diagram shows the VLANs and subnet information necessary to establish LGW BGP connectivity:
Figure 10.10 – Service link and LGW traffic segregated using VLANs
The following table breaks down the configuration required for the LGW BGP connectivity:
| VLAN | BGP | Device | LAG | BGP Subnet | OND IP | CND IP | Outposts ASN | Organization ASN |
| VLAN B | Local gateway BGP 1 | OND1 to CND1 | LAG 1 | 169.254.2.0/30 | 169.254.2.1/30 | 169.254.2.2/30 | 65024 | 65000 |
| Local gateway BGP 2 | OND2 to CND2 | LAG 2 | 169.254.4.0/30 | 169.254.4.1/30 | 169.254.4.2/30 |
Table 10.5 – Sample BGP parameters for LGW connectivity
Service link infrastructure subnet
A service link infrastructure subnet that resides on AWS Outposts establishes service link connectivity to the AWS Region. The subnet that connects to the AWS Region uses a /26 CIDR range and can be configured with either public IP addresses that can be reached directly over the internet or private IP addresses that are NAT-ed and can access the internet. The /26 CIDR range is divided into two /27 CIDR blocks to support link and device failures.