Asymmetric Routing Tradeoffs and Cautions

Tradeoffs – Server’s Route:

• Adjusting routes on the servers can be confusing to set up properly
• Understanding the routing tables during later admin or troubleshooting work may be confusing (Good documentation and procedures are required).
• All traffic out from the servers goes via the WebMux so it may be suboptimal in situation where back-end servers do a lot more than the load-balanced operations. (…but that less burden on the WebMux than SNAT, so it is more an ongoing admin documentation and training issue.)

Tradeoff – SNAT

• The WebMux becomes the client at the TCP level, so the server doesn’t see the real client
• Some applications may need Layer 7 fixes so that the server can see the client.
• Each connection use a TCP port of an IP address on the WebMux. WebMux will need an additional IP address for each increment of 65,535 connections.