From fbb6e58b4f68e631699d5922d541e379cfccbcd3 Mon Sep 17 00:00:00 2001 From: Bryan Boreham Date: Thu, 5 May 2016 12:06:13 +0100 Subject: [PATCH] Add a section explaining WEAVE_MTU for fastdp (#2253) Add a section explaining WEAVE_MTU for fastdp Fixes #2198 --- site/using-weave/fastdp.md | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) diff --git a/site/using-weave/fastdp.md b/site/using-weave/fastdp.md index da7db8d8..619703b1 100644 --- a/site/using-weave/fastdp.md +++ b/site/using-weave/fastdp.md @@ -42,8 +42,26 @@ Where fastdp indicates that fast datapath is being used on a connection. If fast $ weave status connections <- 192.168.122.25:54782 established sleeve 8a:50:4c:23:11:ae(ubuntu1204) +###Packet size (MTU) + +The Maximum Transmission Unit, or MTU, is the technical term for the +limit on how big a single packet can be on the network. Weave Net +defaults to 1410 bytes, but you can set a smaller size if your +underlying network has a tighter limit, or set a larger size for +better performance. + +The underlying network must be able to deliver packets of the size +specified plus overheads of around 50 bytes. This requirement applies +to _every path_ between peers. + +To specify a different MTU, before launching Weave Net set the +environment variable `WEAVE_MTU`. For example, for a typical "jumbo +frame" configuration: + + $ WEAVE_MTU=8950 weave launch host2 host3 + **See Also** * [Using Weave Net](/site/using-weave.md) * [How Fastdp Works](/site/how-it-works/fastdp-how-it-works.md) - + * [Performance measurements](/blog/weave-docker-networking-performance-fast-data-path/)