#Static routes

File: src/topics/routing.j. Path: /ip/route (ROUTE_PATH). Constant: DEFAULT_ROUTE ("0.0.0.0/0").

#Background

A route says: "traffic for network X goes to next hop Y". The routing table is consulted most-specific-first; the default route (0.0.0.0/0) matches everything without a better match - it is "the internet is that way".

Routes come from three sources: connected (created automatically for every interface address), dynamic (routing protocols, DHCP, PPPoE), and static - the ones you place by hand, which is what this topic manages. Note the naming: static routes live under /ip/route; RouterOS's /routing menu holds the dynamic protocols (OSPF, BGP).

When several routes cover the same destination, the distance decides (lower wins) - which makes a higher-distance twin a standby that takes over when the preferred route's gateway dies.

#Struct

mt.Route {
    id, dstAddress, gateway,
    distance,          # string as reported; RouterOS default "1"
    routingTable,      # "main" normally
    active,            # currently used
    dynamic,           # created by a protocol/service - not removable
    disabled, comment
}

#Functions

The gateway may be an IP address or an interface name; if it is not an IP, routeros verifies the interface exists - so both a mistyped address and a mistyped interface fail loudly.

#Examples

Reach a branch office behind another router on the LAN:

mt.addRoute($c, "10.20.0.0/16", "192.168.88.254", "to branch office");

Primary and backup uplink (failover by distance):

mt.addDefaultRoute($c, "203.0.113.1", "primary isp");
mt.addRouteWithDistance($c, "0.0.0.0/0", "198.51.100.1", 10, "backup isp");

While the primary gateway answers, the distance-1 route wins; when it becomes unreachable the distance-10 route takes over.

Inspect the table without the noise of dynamic routes:

def rts as list of mt.Route init mt.routes($c);
for (def rt in $rts) {
    if (not $rt.dynamic) {
        io.printf("%s via %s distance %s active=%t\n",
            $rt.dstAddress, $rt.gateway, $rt.distance, $rt.active);
    }
}

#Policy routing rules

Paths: /routing/rule (ROUTING_RULE_PATH), /routing/table (ROUTING_TABLE_PATH) - RouterOS v7 (v6 kept rules under /ip/route/rule; generic verbs there).

Distance-based failover switches uplinks for everyone; policy routing decides per source: "the guest subnet uses the backup line, always". A rule is checked before the main table and sends matching traffic to another routing table - no per-packet marking involved, which makes rules the simpler and cheaper alternative to the mangle topic's markRoutingFor whenever a source match is enough (marks remain for matches that need full firewall power: ports, protocols, address lists).

# guests use the backup ISP, everything else stays on main
mt.useRoutingTable($c, "10.30.0.0/24", "backupisp", "guests via backup");
# the table is created if missing - it still needs its default route:
mt.add($c, mt.ROUTE_PATH, {"dst-address": "0.0.0.0/0",
    "gateway": "198.51.100.1", "routing-table": "backupisp"});

useRoutingTable uses action lookup: destinations the table cannot answer fall back to the main table (graceful). useRoutingTableOnly is the strict variant - "backup uplink or nothing". routingRules(c) lists them in evaluation order; removeRoutingRule(c, srcAddress, table) undoes one. All adds are idempotent by source + table.

#Pitfalls

• The gateway must be directly reachable (inside a connected network). A route via an address the router cannot reach shows active == false and does nothing.
• removeRoute / enableRoute / disableRoute match the destination string exactly as listed and only consider static routes; with several static routes to the same destination (failover pairs) the first listed is affected - use ids from routes(c) with the generic verbs for surgical work.
• A WAN configured via dhcp.md or ppp.md installs its own dynamic default route. Adding a static one on top creates competition - either let the WAN own it, or disable addDefaultRoute in setupWanWith and manage it here.
• Distance-based failover reacts to the gateway becoming unreachable (ARP), not to "the internet behind it is broken". Recursive gateway checks exist in RouterOS (check-gateway, scope tricks) via the generic verbs.
• A policy-routed table without a default route makes its sources' internet unreachable (useRoutingTableOnly) or silently fall back to main (useRoutingTable) - either way, give the table its route.
• Replies to inbound connections follow the rules too: with two uplinks, connections arriving on the backup line need their replies routed back out the same way (a rule per uplink source, or connection marks via mangle.md).

#Related

• ip.md (connected routes), dhcp.md / ppp.md (dynamic default routes), wireguard.md (allowed-address creates routes too).