Improve check-isp.rsc documentation and code formatting

routeros/check-isp.rsc

@@ -1,20 +1,44 @@
-:local PingCount 5;
-:local CheckIp1 77.88.8.8;
-:local CheckIp2 77.88.8.1;
-:local isp1 [/ping $CheckIp1 count=$PingCount interface="ether1"];
-:local isp2 [/ping $CheckIp2 count=$PingCount interface="ether2"];
+# Dual-WAN (dual-ISP) health check and failover helper.
+#
+# Pings a reachable host through each uplink. If an uplink loses connectivity
+# (zero successful replies), its marked connections are flushed from the
+# connection tracking table so that traffic re-routes through the other ISP.
+#
+# Intended to run periodically from the scheduler, e.g.:
+#   /system scheduler
+#   add name=check-isp interval=30s on-event="/import file-name=check-isp.rsc"
+#
+# Requirements:
+#   - ether1 / ether2 are the ISP1 / ISP2 uplinks (adjust below if different).
+#   - Mangle rules mark per-ISP connections as con-isp1 / con-isp2.
 
-:if ($isp1=0) do={
-:delay 2
-:log warning "ISP1 down";
-/ip firewall connection remove [ find where connection-mark="con-isp1"];
-:delay 2
-:log warning "ISP1 connection reset";
+# --- Settings -------------------------------------------------------------
+:local PingCount 5;            # number of echo requests per check
+:local Isp1Iface "ether1";     # ISP1 uplink interface
+:local Isp2Iface "ether2";     # ISP2 uplink interface
+:local CheckIp1 77.88.8.8;     # host probed through ISP1
+:local CheckIp2 77.88.8.1;     # host probed through ISP2
+
+# --- Probe each uplink (number of successful replies, 0 = down) ----------
+:local isp1 [/ping $CheckIp1 count=$PingCount interface=$Isp1Iface];
+:local isp2 [/ping $CheckIp2 count=$PingCount interface=$Isp2Iface];
+
+# --- ISP1 failover --------------------------------------------------------
+:if ($isp1 = 0) do={
+    :log warning "ISP1 down";
+    :delay 2s;
+    # Flush ISP1-marked connections so sessions re-route via ISP2.
+    /ip firewall connection remove [find where connection-mark="con-isp1"];
+    :delay 2s;
+    :log warning "ISP1 connection reset";
 }
-:if ($isp2=0) do={
-:delay 2
-:log warning "ISP2 down";
-/ip firewall connection remove [ find where connection-mark="con-isp2"];
-:delay 2
-:log warning "ISP2 connection reset";
+
+# --- ISP2 failover --------------------------------------------------------
+:if ($isp2 = 0) do={
+    :log warning "ISP2 down";
+    :delay 2s;
+    # Flush ISP2-marked connections so sessions re-route via ISP1.
+    /ip firewall connection remove [find where connection-mark="con-isp2"];
+    :delay 2s;
+    :log warning "ISP2 connection reset";
 }