(split) LDP_man-pages: update original to v3.34.

[linuxjm/LDP_man-pages.git] / original / man7 / ip.7

diff --git a/original/man7/ip.7 b/original/man7/ip.7
index 4561b2f..9f560df 100644 (file)
--- a/original/man7/ip.7
+++ b/original/man7/ip.7
@@ -9,7 +9,7 @@
 .\"
 .\" FIXME: Document IP_MINTTL, added in Linux 2.6.34
 .\"
-.TH IP  7 2010-10-24 "Linux" "Linux Programmer's Manual"
+.TH IP  7 2011-09-22 "Linux" "Linux Programmer's Manual"
 .SH NAME
 ip \- Linux IPv4 protocol implementation
 .SH SYNOPSIS
@@ -310,27 +310,36 @@ Only valid as a
 .\" Precisely: 2.1.124
 Set or receive the Path MTU Discovery setting for a socket.
 When enabled, Linux will perform Path MTU Discovery
-as defined in RFC\ 1191
-on this socket.
-The don't-fragment flag is set on all outgoing datagrams.
-The system-wide default is controlled by the
-.I /proc/sys/net/ipv4/ip_no_pmtu_disc
-file for
+as defined in RFC\ 1191 on
 .B SOCK_STREAM
-sockets, and disabled on all others.
+sockets.
 For
 .RB non- SOCK_STREAM
-sockets, it is the user's responsibility to packetize the data
-in MTU sized chunks and to do the retransmits if necessary.
-The kernel will reject packets that are bigger than the known
-path MTU if this flag is set (with
-.B EMSGSIZE
-).
+sockets,
+.B IP_PMTUDISC_DO
+forces the don't-fragment flag to be set on all outgoing packets.
+It is the user's responsibility to packetize the data
+in MTU-sized chunks and to do the retransmits if necessary.
+The kernel will reject (with
+.BR EMSGSIZE )
+datagrams that are bigger than the known path MTU.
+.B IP_PMTUDISC_WANT
+will fragment a datagram if needed according to the path MTU,
+or will set the don't-fragment flag otherwise.
+
+The system-wide default can be toggled between
+.B IP_PMTUDISC_WANT
+and
+.B IP_PMTUDISC_DONT
+by writing (respectively, zero and nonzero values) to the
+.I /proc/sys/net/ipv4/ip_no_pmtu_disc
+file.
+
 .TS
 tab(:);
 c l
 l l.
-Path MTU discovery flags:Meaning
+Path MTU discovery value:Meaning
 IP_PMTUDISC_WANT:Use per-route settings.
 IP_PMTUDISC_DONT:Never do Path MTU Discovery.
 IP_PMTUDISC_DO:Always do Path MTU Discovery.
@@ -343,10 +352,10 @@ When it is connected to a specific peer with
 .BR connect (2),
 the currently known path MTU can be retrieved conveniently using the
 .B IP_MTU
-socket option (e.g., after a
+socket option (e.g., after an
 .B EMSGSIZE
 error occurred).
-It may change over time.
+The path MTU may change over time.
 For connectionless sockets with many destinations,
 the new MTU for a given destination can also be accessed using the
 error queue (see