Switch your RouterBoard
● Daniel Starnowski
Switch chip on MikroTik RouterBoard
● It is really easy!
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RouterBoard – just an example
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OSI layers
● Switch operates on layer 2 and
forwards ethernet frames between
ports
● Router operates on layer 3 and
forwards IP packets decapsulating
them from frames
MAC header IP header Layer 4 + data CRC
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RouterBoard – the anatomy
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RouterBoard – ports and interfaces
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RouterBoard – a routing scenario
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RouterBoard – a bridge
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RouterBoard – IP address on a bridge
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RB2011 – the performance
● fast path:
~1500 Mbps with 1500 B packets
~150 Mbps with 64 B packets
● without fast path:
~1000 Mbps with 1500 B packets
~50 Mbps with 64 B packets
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RouterBoard – VLAN bridging
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RouterBoard – VLAN bridging config
● Create VLAN vlan33eth1 with tag
33 on interface ether1
● Create VLAN vlan33eth2 on ether2
● Create bridge vlan33
● Add ports vlan33eth1, vlan33eth2
and ether3 to the bridge vlan33
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RB2011 – VLAN bridging test
● 8 different streams
● Only 1500 B packets
● 8 x 122 Mbps – 1% packet loss
(total 976 Mbps)
● 8 x 60 Mbps – 0,1% packet loss
(total 480 Mbps)
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The answer – the switch chip
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The switch chip
● Almost every new RouterBoard with
multiple ethernet interfaces is
equipped with a switch chip
● Hardware switch without using CPU
● From ROS v6 – VLAN trunking is
possible
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Switch chips in MikroTik devices
● Atheros 8316
● Atheros 8327
● Atheros 8227
● Atheros 7240
● other
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What chip does my RouterBoard have?
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How to turn the switch chip on?
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How to turn the switch chip on?
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Activating the switch chip
● If we set „master port“ on ether2 to
„ether1“, we will activate the switch
chip.
● How many ports will be active on the
chip?
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Connections without using the chip
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Activating the switch chip
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Switch chip – the master port
● Master port – only in the same chip
● Only 1 master port possible for a chip
● The master and „slave“ ports are
equal for the switch chip
● Only one difference – the interface,
the chip will be visible on
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Switch chip – port names
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Switch chip – port names
● The same names:
– interfaces seen from the CPU
(ether1, ether2, ...)
– physical ports seen from the chip
(ether1, ether2, ...)
● Only one connection between the chip
(the cpu port) and the CPU (master port)
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Default configuration of switch chip
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Default configuration of switch chip
● In RouterBoards like 2011 or 951
● ether1 – gateway port (not included
in the switch group)
● ether2-ether5 – switched ports
● ether2 – master port, used when
configuring IP address, bridge, etc.
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VLAN bridging – the software version
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VLAN bridging with the switch chip
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Switch chip – preparing the vlans
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Switch chip – preparing the vlans
● Vlan settings not important as long as
VLAN Mode is disabled (default)
● Independent learning – when some
MACs can be visible on different
ports in different vlans
– Keeps separate table for the VLAN
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Switch chip – the trunk port
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Switch chip – the access port
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Switch chip – trunk and access ports
● Trunk port:
– Mode: secure
– Header: add if missing
● Access port:
– Mode: secure
– Header: always strip
– Default VLAN ID (a.k.a. PVID)
● No „hybrid“ ports!
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Switch chip – the speed test
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Switch chip – the speed test
● With bridging – more than 0.1% loss
visible with 8*60 = 480 Mbps (and
CPU ~ 50%)
● Switch chip – almost no loss with
8*490 Mbps = 3920 Mbps (4 ports
wire speed), CPU unchanged
● From ROS 6.5 – port stats available
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Switch chip
– port stats
● From ROS 6.5
stats available
for the switch
ports (traffic
doesn't need to
go through
CPU
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Switch chip – routing the VLANs
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Switch chip – routing the VLANs
● Include cpu in selected VLANs
configuration on the switch chip
● Change VLAN Mode to secure
(header can be leave as is)
● Add VLAN interfaces on the master
port (in the example – ether1)
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What if ether3 was the master port?
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Hosts table
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Switch chip's limitations
● Mirroring – copies of all frames (in
and out) from source sent to target
● Rules – if we want to mirror or block
(etc.) a selected packets
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Thank you!
● I told you it was easy!
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