KCC: (doc) explain intrasite max edge count a bit better

Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Garming Sam <garming@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>

diff --git a/source4/scripting/bin/samba_kcc b/source4/scripting/bin/samba_kcc
index 72d58345befb50cb754fd5ce324f6f60af1934a0..28c4dfe49189314fde9a55aa10b1158138fd3ffc 100755 (executable)
--- a/source4/scripting/bin/samba_kcc
+++ b/source4/scripting/bin/samba_kcc
@@ -1903,6 +1903,14 @@ class KCC(object):
          50   48 4903
 
         :param node_count: total number of nodes in the replica graph
+
+        The intention is that there should be no more than 3 hops
+        between any two DSAs at a site. With up to 7 nodes the 2 edges
+        of the ring are enough; any configuration of extra edges with
+        8 nodes will be enough. It is less clear that the 3 hop
+        guarantee holds at e.g. 15 nodes in degenerate cases, but
+        those are quite unlikely given the extra edges are randomly
+        arranged.
         """
         n = 0
         while True: