From 0f22007377e186b9a16839c31156190d378fcffc Mon Sep 17 00:00:00 2001
From: bodea <bodea>
Date: Sat, 4 Jun 2005 15:40:53 +0000
Subject: [PATCH] Add note about fragmentation in Docs/manual.html, and a
 sample iptables rule for MSS clamping.

---
 Docs/manual.html | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/Docs/manual.html b/Docs/manual.html
index 4db3a83..a857d9b 100644
--- a/Docs/manual.html
+++ b/Docs/manual.html
@@ -56,6 +56,7 @@ H3 {
     <LI><A HREF="#Filtering">Filtering</A></LI>
     <LI><A HREF="#Clustering">Clustering</A></LI>
     <LI><A HREF="#Routing">Routing</A></LI>
+    <LI><A HREF="#AvoidingFragmentation">Avoiding Fragmentation</A></LI>
     <LI><A HREF="#Performance">Performance</A></LI>
 </OL>
 
@@ -1030,6 +1031,22 @@ ibgp" for IBGP.  If this is not supported by your IOS revision, you
 can use "maximum-paths" (which works for EBGP) and set
 <B>as_number</B> to a private value such as 64512.<P>
 
+<H2 ID="AvoidingFragmentation">Avoiding Fragmentation</H2>
+
+Fragmentation of encapsulated return packets to the LAC may be avoided
+for TCP sessions by adding a firewall rule to clamps the MSS on
+outgoing SYN packets.
+
+The following is appropriate for interfaces with a typical MTU of
+1500:
+
+<pre>
+iptables -A FORWARD -i tun+ -o eth0 	\
+    -p tcp --tcp-flags SYN,RST SYN	\
+    -m tcpmss --mss 1413:1600		\
+    -j TCPMSS --set-mss 1412
+</pre>
+
 <H2 ID="Performance">Performance</H2>
 
 Performance is great.<P>
-- 
2.20.1