X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=Documentation%2Fnetworking%2Fip-sysctl.txt;h=d99940dcfc442c7a3ae5e209c0eef4af99d3d876;hb=9fe146aef44afe5ec677d8150b6ae94e09b773f7;hp=c7165f4cb7927a152ec547caeecb393f5ad3c27e;hpb=4390110fef9e5c64e10c6ca19d586932242c9a8a;p=pandora-kernel.git

diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index c7165f4cb792..d99940dcfc44 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -11,7 +11,9 @@ ip_forward - BOOLEAN
 	for routers)
 
 ip_default_ttl - INTEGER
-	default 64
+	Default value of TTL field (Time To Live) for outgoing (but not
+	forwarded) IP packets. Should be between 1 and 255 inclusive.
+	Default: 64 (as recommended by RFC1700)
 
 ip_no_pmtu_disc - BOOLEAN
 	Disable Path MTU Discovery.
@@ -20,6 +22,15 @@ ip_no_pmtu_disc - BOOLEAN
 min_pmtu - INTEGER
 	default 562 - minimum discovered Path MTU
 
+route/max_size - INTEGER
+	Maximum number of routes allowed in the kernel.  Increase
+	this when using large numbers of interfaces and/or routes.
+
+neigh/default/gc_thresh3 - INTEGER
+	Maximum number of neighbor entries allowed.  Increase this
+	when using large numbers of interfaces and when communicating
+	with large numbers of directly-connected peers.
+
 mtu_expires - INTEGER
 	Time, in seconds, that cached PMTU information is kept.
 
@@ -135,6 +146,7 @@ tcp_adv_win_scale - INTEGER
 	Count buffering overhead as bytes/2^tcp_adv_win_scale
 	(if tcp_adv_win_scale > 0) or bytes-bytes/2^(-tcp_adv_win_scale),
 	if it is <= 0.
+	Possible values are [-31, 31], inclusive.
 	Default: 2
 
 tcp_allowed_congestion_control - STRING
@@ -698,10 +710,28 @@ igmp_max_memberships - INTEGER
 	Change the maximum number of multicast groups we can subscribe to.
 	Default: 20
 
-conf/interface/*  changes special settings per interface (where "interface" is
-		  the name of your network interface)
-conf/all/*	  is special, changes the settings for all interfaces
+	Theoretical maximum value is bounded by having to send a membership
+	report in a single datagram (i.e. the report can't span multiple
+	datagrams, or risk confusing the switch and leaving groups you don't
+	intend to).
+
+	The number of supported groups 'M' is bounded by the number of group
+	report entries you can fit into a single datagram of 65535 bytes.
+
+	M = 65536-sizeof (ip header)/(sizeof(Group record))
+
+	Group records are variable length, with a minimum of 12 bytes.
+	So net.ipv4.igmp_max_memberships should not be set higher than:
+
+	(65536-24) / 12 = 5459
+
+	The value 5459 assumes no IP header options, so in practice
+	this number may be lower.
+
+	conf/interface/*  changes special settings per interface (where
+	"interface" is the name of your network interface)
 
+	conf/all/*	  is special, changes the settings for all interfaces
 
 log_martians - BOOLEAN
 	Log packets with impossible addresses to kernel log.