From 7dc86c4c16ebc995154356730dfc6bc09d7b7ce6 Mon Sep 17 00:00:00 2001
From: Markus Hauschild <markus@moepman.eu>
Date: Mon, 3 Apr 2017 22:36:10 +0200
Subject: [PATCH] Optimize arp broadcasts via dhcp hooks

---
 roles/dhcpd/templates/dhcpd.conf.j2 | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/roles/dhcpd/templates/dhcpd.conf.j2 b/roles/dhcpd/templates/dhcpd.conf.j2
index d86f69d..362a921 100644
--- a/roles/dhcpd/templates/dhcpd.conf.j2
+++ b/roles/dhcpd/templates/dhcpd.conf.j2
@@ -28,4 +28,18 @@ subnet {{ batman_ipv4 | ipaddr('network') }} netmask {{ batman_ipv4 | ipaddr('ne
   pool {
     range {{ dhcpd_first }} {{ dhcpd_last }} ;
   }
+  # use static arp entries to reduce broadcast
+  on commit {
+    set clip = binary-to-ascii(10, 8, ".", leased-address);
+    set clhw = binary-to-ascii(16, 8, ":", substring(hardware, 1, 6));
+    execute("/sbin/arp", "-s", clip, clhw);
+  }
+  on release {
+    set clip = binary-to-ascii(10, 8, ".", leased-address);
+    execute("/sbin/arp", "-d", clip);
+  }
+  on expiry {
+    set clip = binary-to-ascii(10, 8, ".", leased-address);
+    execute("/sbin/arp", "-d", clip);
+  }
 }