X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/tripe/blobdiff_plain/92e57abc8b98e5c28b6d6b4e9e3bf8735c0746c4..65faf8dff03b7ed638341b6105b26addae28d641:/keys/tripe-keys.8.in

diff --git a/keys/tripe-keys.8.in b/keys/tripe-keys.8.in
index eb2604b8..ce3c1ec1 100644
--- a/keys/tripe-keys.8.in
+++ b/keys/tripe-keys.8.in
@@ -55,6 +55,8 @@ tripe-keys \- simple centralized key management for tripe
 .B "rebuild"
 .br
 .B "clean"
+.br
+.BR "mtu " [ \fIpath-mtu ]
 .
 .\"--------------------------------------------------------------------------
 .SH "DESCRIPTION"
@@ -215,6 +217,18 @@ might have written to a directory.  In particular, it deletes
 and their associated
 .B .old
 files.
+.TP
+.BR "mtu " [ \fIpath-mtu ]
+Write, as a decimal number on standard output, the recommended MTU for a
+TrIPE tunnel interface, given that the
+.I path-mtu
+between two peers is as specified.  The default is 1500, which is very
+commonly correct, but you should check using a tool such as
+.BR tracepath (8).
+Getting the MTU too big will lead to unnecessary fragmentation of
+TrIPE's UDP datagrams; getting it too small will fail to utilize the
+underlying network effectively.  If in doubt, it's therefore better to
+underestimate.
 .
 .\"--------------------------------------------------------------------------
 .SH "SEE ALSO"