The default and usually the preferred way for a client to chat with a Redis server is using the TCP protocol described in the Protocol Specification. In some environments the trade off of switching to a less reliable and not feature complete protocol running over UDP in order to improve latency is a good idea, so starting from Redis 2.2 there is support for a binary UDP protocol.
Based on a recent ☞ tweet it looks like the new Redis UDP protocol is already delivering some good results:
There are advantages (200k req/sec) but not so big as reported
Update: there are more comments about the performance of the Redis UDP protocol:
weird UDP results… in my over-ethernet tests, sometimes much faster, sometimes slower. I need to understand better what’s going on…
From the data I’ve currently, UDP is a big win when there are many clients interested in the same redis instance. For instance in clusters. So you got 100 redis servers and 500 FEPs. For this tasts UDP is the way to go. And indeed, Facebook is using memcached like that