From 3b3d5e62616d856364b259680cabb3e1c406c273 Mon Sep 17 00:00:00 2001
From: Matthias Radestock <matthias.radestock@gmail.com>
Date: Thu, 18 Dec 2014 18:21:31 +0000
Subject: [PATCH] document mac_cache max age constraint

---
 router/router.go | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/router/router.go b/router/router.go
index cb97d095..7ca8a306 100644
--- a/router/router.go
+++ b/router/router.go
@@ -12,7 +12,10 @@ import (
 	"time"
 )
 
-const macMaxAge = 10 * time.Minute
+const macMaxAge = 10 * time.Minute // [1]
+
+// [1] should be greater than typical ARP cache expiries, i.e. > 3/2 *
+// /proc/sys/net/ipv4_neigh/*/base_reachable_time_ms on Linux
 
 func NewRouter(iface *net.Interface, name PeerName, password []byte, connLimit int, bufSz int, logFrame func(string, []byte, *layers.Ethernet)) *Router {
 	onMacExpiry := func(mac net.HardwareAddr, peer *Peer) {