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@jennifer/routeros

Bridges

File: src/topics/bridges.j. Paths: /interface/bridge (BRIDGE_PATH), /interface/bridge/port (BRIDGE_PORT_PATH).

Background

A bridge is a virtual switch inside the router: every interface you add to it as a port shares one layer-2 network, as if plugged into the same physical switch. This is how a MikroTik becomes a home router in the classic sense - LAN ports and WiFi bridged into one network, with the router's LAN address sitting on the bridge, not on any single port.

Two lists are involved: the bridges themselves, and the bridge ports (the membership records that say "ether2 belongs to brlan").

Structs

jennifer
mt.Bridge     { id, name, mac, running, disabled, comment }
mt.BridgePort { id, bridge, interfaceName, disabled }

Functions

FunctionPurpose
bridges(c) → list of Bridgeall bridges
addBridge(c, name) → idcreate a bridge
removeBridge(c, name)delete a bridge by name
bridgePorts(c, bridgeName) → list of BridgePortmembers of one bridge
addBridgePort(c, bridgeName, interfaceName) → idattach an interface
removeBridgePort(c, interfaceName)detach an interface from its bridge

addBridgePort verifies the bridge exists first, so a typo in the bridge name fails with a clear message instead of creating an orphan port.

Examples

The classic home-router LAN - three wired ports and the WiFi in one network:

jennifer
mt.addBridge($c, "brlan");
mt.addBridgePort($c, "brlan", "ether2");
mt.addBridgePort($c, "brlan", "ether3");
mt.addBridgePort($c, "brlan", "ether4");
mt.addBridgePort($c, "brlan", "wlan1");

# the LAN address lives on the bridge
mt.addIpAddress($c, "192.168.88.1/24", "brlan");

Audit which port belongs where:

jennifer
def ports as list of mt.BridgePort init mt.bridgePorts($c, "brlan");
for (def p in $ports) {
    io.printf("%s is on %s\n", $p.interfaceName, $p.bridge);
}

Move a port to another bridge (detach, then attach):

jennifer
mt.removeBridgePort($c, "ether4");
mt.addBridgePort($c, "brguest", "ether4");

Pitfalls

  • Never bridge the WAN port into the LAN - that connects your ISP to your internal network at layer 2.
  • An interface can be a port of only one bridge; removeBridgePort takes just the interface name for that reason.
  • Addresses belong on the bridge, not on member ports. An address on ether2 stops working the moment ether2 joins a bridge.
  • Removing a bridge does not fail on existing ports - RouterOS drops the memberships; remove the ports first if you want an explicit teardown.
  • vlans.md - VLANs often ride on a bridge.
  • dhcp.md - serve DHCP on the bridge to make the LAN plug-and-play.