Technical Requirements

Supported tunneling technologies

• GRE
  • IPv4
• IPIP
  • IPv4
• IP6TNL
  • IPv6

Customer hardware requirements when using tunnels

When terminating a tunnel, your hardware will drastically affect the performance of the tunnel. Generally the most essential item is your router supporting hardware offload for whichever tunneling protocol is being used. As an example, most modern routers support GRE offloading, but you can refer to your specific manufacturer's documentation to check this. 

Customer software requirements when using tunnels

MTU must be appropriately adjusted on the router to accommodate the overhead of whichever tunneling software is used. In the case of GRE over IPv4, there's an additional 20 byte IP header and 4 byte GRE header. As such, the MTU is reduced from 1500 to 1476. In the case of symmetric routing (both ingress and egress pass over Path's network), TCP MSS is clamped to 1400 bytes to reduce the chance of problems arising from misconfigured MTU on the customer's end. For asymmetric customers, this will need to be done on their side.

Setting the correct MTU is crucial for performance, as this avoids un-needed fragmentation which is computationally expensive.

BGP requirements

• ASN - Customer must have a public ASN
• Publically routable IP Space 
• Proper route objects
  • Route Object for all prefixes
  • RPKI / ROA for all prefixes
  • AS-SET if you have downstream ASNs