Multi-hop BGP Explained

Products

• VMware SD-WAN by VeloCloud

Issue/Introduction

The purpose is to give more information on Multi-hop BGP to better understand what features are supported, what versions they exist in, how to troubleshoot and any known bugs. 

Environment

VMware SD-WAN by VeloCloud

Resolution

Data points:

• Multi-hop is for iBGP and eBGP
• Next hop might not be reachable through a direct route. The solution is recursive route lookup.
• Local IP: Equivalent of loopback IP, to source the BGP neighborship from
• Max-hop is configured for eBGP peers under additional options (iBGP is implicitly multi-hop)
• May need a static route to resolve ip address of bgp neighbor
• Local IP is configured under additional options
• We don't advertise the local ip to peers. Customers need to have that routing info on their own.

A note about recursive next hop resolution - it only applies to resolving BGP next hop results, but if an ER comes in it would be easy to add for other types of routes.