From be1c5b53227ba8280f1ebb01c6f5da3c9eebdaad Mon Sep 17 00:00:00 2001
From: xu xin <xu.xin16@zte.com.cn>
Date: Thu, 30 Dec 2021 03:28:56 +0000
Subject: [PATCH] Documentation: fix outdated interpretation of ip_no_pmtu_disc
The updating way of pmtu has changed, but documentation is still in the
old way. So this patch updates the interpretation of ip_no_pmtu_disc and
min_pmtu.
See commit 28d35bcdd3925 ("net: ipv4: don't let PMTU updates increase
route MTU")
Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: xu xin <xu.xin16@zte.com.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
Documentation/networking/ip-sysctl.rst | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
index c04431144f7ab..2572eecc3e86a 100644
--- a/Documentation/networking/ip-sysctl.rst
+++ b/Documentation/networking/ip-sysctl.rst
@@ -25,7 +25,8 @@ ip_default_ttl - INTEGER
ip_no_pmtu_disc - INTEGER
Disable Path MTU Discovery. If enabled in mode 1 and a
fragmentation-required ICMP is received, the PMTU to this
- destination will be set to min_pmtu (see below). You will need
+ destination will be set to the smallest of the old MTU to
+ this destination and min_pmtu (see below). You will need
to raise min_pmtu to the smallest interface MTU on your system
manually if you want to avoid locally generated fragments.
@@ -49,7 +50,8 @@ ip_no_pmtu_disc - INTEGER
Default: FALSE
min_pmtu - INTEGER
- default 552 - minimum discovered Path MTU
+ default 552 - minimum Path MTU. Unless this is changed mannually,
+ each cached pmtu will never be lower than this setting.
ip_forward_use_pmtu - BOOLEAN
By default we don't trust protocol path MTUs while forwarding
--
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