From de72402954abc382e63532e6d179583c5eea6227 Mon Sep 17 00:00:00 2001
From: Ethan Jackson <ethan@nicira.com>
Date: Tue, 30 Aug 2011 17:37:15 -0700
Subject: cfm: Allow accurate transmission intervals in extended mode.

The standard CFM protocol only allows a handful of transmission
rates.  This is particularly problematic if you want to support a
transmission rate slower than 100 ms and faster than 1000 ms.

This patch allows arbitrary transmission rates (between 1 ms and
65535 ms).  It does this by commandeering parts of a reserved
"zero" field in the ccm message.  This breaks wire compatibility
with standard 802.1ag implementations, and thus is only supported
in extended mode.

Bug #7014.
---
 vswitchd/vswitch.xml | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

(limited to 'vswitchd')

diff --git a/vswitchd/vswitch.xml b/vswitchd/vswitch.xml
index 5151fea21..daac9e1db 100644
--- a/vswitchd/vswitch.xml
+++ b/vswitchd/vswitch.xml
@@ -1429,7 +1429,10 @@
           <dd> When true, the CFM module operates in extended mode. This causes
             it to use a nonstandard destination address to avoid conflicting
             with compliant implementations which may be running concurrently on
-            the network. Defaults to false. </dd>
+            the network. Furthermore, extended mode increases the accuracy of
+            the <code>cfm_interval</code> configuration parameter by breaking
+            wire compatibility with 802.1ag compliant implementations.
+            Defaults to false.</dd>
           <dt><code>bond-stable-id</code></dt>
           <dd> A positive integer using in <code>stable</code> bond mode to
             make slave selection decisions.  Allocating
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