Connectivity through service link
During AWS Outposts provisioning, you or AWS creates a service link connection that connects your Outposts server to your chosen AWS Region or home Region. The service link is an encrypted set of VPN connections that are used whenever the Outpost communicates with your chosen home Region. You use a virtual LAN (VLAN) to segment traffic on the service link. The service link VLAN enables communication between the Outpost and the AWS Region for both management of the Outpost and intra-VPC traffic between the AWS Region and Outpost.
The Outpost is able to create the service link VPN back to the AWS Region through public Region connectivity. To do so, the Outpost needs connectivity to the AWS Region's public IP ranges, either through the public internet or AWS Direct Connect public virtual interface. This connectivity can be through specific routes in the service link VLAN, or through a default route of 0.0.0.0/0. For more information about the public ranges for AWS, see AWS IP Address Ranges.
After the service link is established, the Outpost is in service and managed by AWS. The service link is used for the following traffic:
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Management traffic to the Outpost through the service link, including internal control plane traffic, internal resource monitoring, and updates to firmware and software.
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Traffic between the Outpost and any associated VPCs, including customer data plane traffic.
Service link maximum transmission unit (MTU) requirements
The maximum transmission unit (MTU) of a network connection is the size, in bytes, of the largest permissible packet that can be passed over the connection. The network must support 1500-bytes MTU between the Outpost and the service link endpoints in the parent AWS Region.
Traffic that goes from an instance in Outposts to an instance in the Region has an MTU of 1300.
Service link bandwidth recommendations
For an optimal experience and resiliency, AWS requires that you use redundant connectivity of at least 500 Mbps and a maximum of 175 ms round trip latency for the service link connection to the AWS Region. The maximum utilization for each Outposts server is 500 Mbps. To increase the connection speed, use multiple Outposts servers. For example, if you have three AWS Outposts servers, the maximum connection speed increases to 1.5 Gbps (1,500 Mbps). For more information, see Service link traffic for servers.
Your AWS Outposts service link bandwidth requirements vary depending on workload characteristics, such as AMI size, application elasticity, burst speed needs, and Amazon VPC traffic to the Region. Note that AWS Outposts servers do not cache AMIs. AMIs are downloaded from the Region with every instance launch.
To receive a custom recommendation about the service link bandwidth required for your needs, contact your AWS sales representative or APN partner.
Redundant internet connections
When you build connectivity from your Outpost to the AWS Region, we recommend that you
create multiple connections for higher availability and resiliency. For more information, see
AWS Direct Connect Resiliency
Recommendations
If you need connectivity to the public internet, you can use redundant internet connections and diverse internet providers, just as you would with your existing on-premises workloads.
