1 files changed, 19 insertions, 0 deletions

diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 006b39dec87d..c532884f4fec 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -692,6 +692,25 @@ proxy_arp - BOOLEAN
         conf/{all,interface}/proxy_arp is set to TRUE,
         it will be disabled otherwise
 
+proxy_arp_pvlan - BOOLEAN
+        Private VLAN proxy arp.
+        Basically allow proxy arp replies back to the same interface
+        (from which the ARP request/solicitation was received).
+
+        This is done to support (ethernet) switch features, like RFC
+        3069, where the individual ports are NOT allowed to
+        communicate with each other, but they are allowed to talk to
+        the upstream router.  As described in RFC 3069, it is possible
+        to allow these hosts to communicate through the upstream
+        router by proxy_arp'ing. Don't need to be used together with
+        proxy_arp.
+
+        This technology is known by different names:
+          In RFC 3069 it is called VLAN Aggregation.
+          Cisco and Allied Telesyn call it Private VLAN.
+          Hewlett-Packard call it Source-Port filtering or port-isolation.
+          Ericsson call it MAC-Forced Forwarding (RFC Draft).
+
 shared_media - BOOLEAN
         Send(router) or accept(host) RFC1620 shared media redirects.
         Overrides ip_secure_redirects.