README.md

Documentation

Example Vagrant Setup - if you want to get all components up and running in a test environment and look around at how different GLB components work together.
Known Compatible DPDK configurations - if you want to see examples of how GitHub configures DPDK in its datacenters, or how to use it on a public cloud provider that supports DPDK and BGP.
Packages and quick start guide - included packages and quick-start instructions for relevant files needed to configure them.
glb-director component configuration options - configuration options for the GLB Director and discussion of NIC/Port and CPU Core configuration.
Forwarding table configuration & healthchecks - Configuring the GLB forwarding table, and the director->proxy healthcheck process.
Backend proxy server setup - Configuring the backend TCP/proxy tier servers.

Some notable known limitations / design decisions of the current implementation:

The datacenter internal MTU is expected to be large enough to encapsulate any user packet inside a GUE header. We use jumbo frames (9000+ MTU) within the datacenter with a transit/internet MTU of 1500. GLB Director will not fragment packets if they are too large.
If GLB is used within a datacenter, proxy servers should know the correct maximum MSS they can use. We tell haproxy to clamp MSS to a small enough value that it can always be encapsulated.
Because of the above 2 points, GLB Director doesn't send ICMP fragmentation required messages when it cannot forward packets.
- GLB Director will, however, forward ICMP fragmentation required packets from outside to the correct proxy server.

GLB Hashing - explains how the GLB forwarding table is generated and the way rendezvous hashing is used to maintain consistent server mapping for client IPs.
Second Chance Design - explains how GLB avoids storing or sharing connection state on the director tier, and compares to some other similar technologies.
GUE Header - lays out the fields of the GLB private data of the GUE (Generic UDP Encapsulation) header that GLB uses to encapsulate and tunnel packets.