Webinar topic: Mikrotik Bridge Deep Dive Presenter: Achmad Mardiansyah In this webinar series, we will discuss about Mikrotik Bridge Deep Dive Please share your feedback or webinar ideas here: http://bit.ly/glcfeedback Check our schedule for future events: https://www.glcnetworks.com/en/schedule/ Follow our social media for updates: Facebook, Instagram, YouTube Channel, and telegram also discord Recording available on Youtube https://youtu.be/AISGc9AGJtE

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Mikrotik bridge:
deep dive
GLC Webinar,
25 nov 2021
Achmad Mardiansyah
achmad@glcnetworks.com
GLC Networks, Indonesia
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Agenda
● Introduction
● Review prerequisite knowledge
● Bridge
● Bridge features
● Live practice
● Q & A
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introduction
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What is GLC?
● Garda Lintas Cakrawala (www.glcnetworks.com)
● Based in Bandung, Indonesia
● Areas: Training, IT Consulting
● Certified partner for: Mikrotik, Ubiquity, Linux foundation
● Product: GLC radius manager
● Regular event
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Trainer Introduction
● Name: Achmad Mardiansyah
● Base: bandung, Indonesia
● Linux user since 1999, mikrotik user since 2007, UBNT
2011
● Mikrotik Certified Trainer
(MTCNA/RE/WE/UME/INE/TCE/IPv6)
● Mikrotik/Linux Certified Consultant
● Website contributor: achmadjournal.com, mikrotik.tips,
asysadmin.tips
● More info:
http://au.linkedin.com/in/achmadmardiansyah
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Past experience
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● 2021 (Congo DRC, Malaysia): network support,
radius/billing integration
● 2020 (Congo DRC, Malaysia): IOT integration,
network automation
● 2019, Congo (DRC): build a wireless ISP from
ground-up
● 2018, Malaysia: network revamp, develop billing
solution and integration, setup dynamic routing
● 2017, Libya (north africa): remote wireless migration
for a new Wireless ISP
● 2016, United Kingdom: workshop for wireless ISP,
migrating a bridged to routed network

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About GLC webinar?
● First webinar: january 1, 2010 (title:
tahun baru bersama solaris - new year
with solaris OS)
● As a sharing event with various topics:
linux, networking, wireless, database,
programming, etc
● Regular schedule
● Irregular schedule: as needed
● Checking schedule:
http://www.glcnetworks.com/schedule
● You are invited to be a presenter
○ No need to be an expert
○ This is a forum for sharing: knowledge,
experiences, information
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Please introduce yourself
● Your name
● Your company/university?
● Your networking experience?
● Your mikrotik experience?
● Your expectation from this course?
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Prerequisite
● This presentation some prerequisite knowledge
● We assume you already understand:
○ Python programming
○ Machine learning
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Review prerequisite knowledge
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7 OSI layer & protocol
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● OSI layer Is a conceptual model from ISO
(International Standard Organization) for project
OSI (Open System Interconnection)
● When you send a message with a courier, you
need to add more info to get your message arrived
at the destination (This process is called
encapsulation)
● What is protocol
○ Is a set of rules for communication
○ Available on each layer
● Communication consist of series encapsulation
○ SDU: service data unit (before PDU)
○ PDU: protocol data unit (after header is added)

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Layered model (TCP/IP vs ISO) and encapsulation
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/ datagram

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Layer 4 header (which one is TCP?)
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Layer 3 header (which one is IPv4?)
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Ethernet header (which is the MTU?)
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802.11 header
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Did you notice?
● There is a big overhead on encapsulation process
● More encapsulation means less payload?
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Connecting Network devices
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Typical network hardware
● End-devices
● Intermediary devices
● Media
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Typical connection (physical topology)
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R2
R1
R3
● Router connects layer 2
segments
● Router works on layer 3
● Meaning, each layer 2
segment has network ID

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Typical connection (logical topology)
Routing table:
● A table at router that is used to forward packet
● Available on every devices (router and host)
● Entry is executed sequentially
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192.168.0.0/26
R1
192.168.0.1/26
192.168.0.3/26
192.168.0.2/26
R3
R2
192.168.1.0/24
192.168.2.0/24
192.168.3.0/24
192.168.3.3/24
192.168.3.9/24
192.168.2.9/24
192.168.2.2/24
192.168.1.1/24
192.168.1.9/24
destination gateway
192.168.0.0/26 direct
192.168.1.0/24 direct
192.168.2.0/24 192.168.0.2
192.168.3.0/24 192.168.0.3
192.168.16.3/32 192.168.0.2
0.0.0.0/0 (default gw) 192.168.0.3

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Layer 2 technology: Ethernet
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Ethernet specs
● Defined by IEEE 802.3
● Media:
○ Coaxial cable
○ Twisted pair
○ Fiber optic
● Devices required:
○ Bridge / switch
○ HUB
● Everyone likes it!!
○ Affordable
○ Easy to install
○ Easy maintenance
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How ethernet works (CSMA/CD)
● Carrier Sense Multiple Access / Collision
Detection (CSMA/CD)
○ Every host do not know when other send data
○ Before sending data, host check the shared medium
○ Every host only knows when collision happens
● You will have:
○ Collision domain
■ Area where collision happens
■ Can use any frame
○ Broadcast domain
■ Area when broadcast happens
■ Using broadcast frame
● CSMA/CD != CSMA/CA
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How ethernet works (ARP)
● ARP = Address resolution protocol
● A mapping between IPv4 and MAC
address
● Requires broadcast frame
● Will be eliminated in IPv6
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Source: ipcisco.com

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Ethernet evolution (1)
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Ethernet evolution (2)
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Ethernet issue: Collision domain
● Area where collision happens. See CSMA/CD
● Some ideas:
○ Using bridged/switched network
○ Now is very hard to find a HUB
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Source: devto.com

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Ethernet issue: Broadcast domain
● An area where broadcast happens
● Try use 5-4-3-2-1 rules
● Broadcast can go wild (especially on infected
hosts)
● Some ideas:
○ Using router to split segments
○ Port isolation on switch
○ Use storm control on switch
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Ethernet issue: Loop
● A condition when frame is forwarded in the
media
● Will stop until one of cable is removed
● Some ideas:
○ Do not use traditional switch
○ activate STP between switch
○ Port isolation
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Ethernet issue: Security
● Issue:
○ ARP poisoning
○ Spoofing
○ DHCP starvation
● Ideas:
○ AAA (Authentication, Authorization,
Accounting)
○ Dot1x
○ Captive portal
○ MAC address authentication
○ Prevent rogue DHCP server
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Layer 2 technology: VLAN
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Without and with VLAN
trunk
link
VLAN 10 VLAN 20 VLAN 10 VLAN 20
SITE A SITE B

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VLAN terms
● VLAN: a feature on layer 2 device (switch) to do virtual segmentation on
physical switch
● The segmentation can be extended to other switch using “trunk” link.
Borrowed from telco terms “trunk” (a link to connects 2 telco exchanges)
● Port types:
○ Access port -> to connect to end-devices
○ Trunk port -> to connect to other VLAN switch
access
port
trunk
port
trunk
port
VLAN 10 VLAN 20 VLAN 10 VLAN 20
SITE A SITE B
trunk
line

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What happened on trunk ports
● The layer-2-header of outgoing frame will be modified by adding VLAN tag on
the header
● This tag will be recognised at the other end
access
port
trunk
port
trunk
port
SITE A SITE B
VLAN 10 VLAN 20 VLAN 10 VLAN 20

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R41
EXAMPLE VLAN TOPOLOGY
1 interface with 3 networks :
- no TAG
- TAG to NON-TAG
- TAG to TAG
PC61
E3
E2
E2
SW51
E2
PC71
E3 E4
br1
e2
e3
br2
vlan10-e2
e4
E2
PC81
E5
br3
vlan20-e2
vlan20-e5

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Mikrotik Bridge
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Mikrotik: router → bridge
● By default configuration, mikrotik is a
router
● But we can turn mikrotik to be a layer 2
device. implementation:
○ Bridge → processed by CPU
○ Switch → processed by hardware chip
● Example configuration
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Source: praktekit.com

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Bridge features: VLAN
● Connecting physical interface and vlan interface
● Connecting between vlan interface
● Implementation
○ Put vlan interface on physical interface OR
○ Put vlan interface on bridge interface
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Bridge features: HW offloading
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Bridge features: STP / RSTP
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Bridge features: filtering
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LIVE practice
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preparation
● SSH client
● SSH parameters
○ SSH address
○ SSH port
○ SSH username
○ SSH password
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Q & A
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Interested? Just come to our training...
● Topics are arranged in systematic and logical way
● You will learn from experienced teacher
● Not only learn the materials, but also sharing experiences, best-practices, and
networking
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End of slides
● Thank you for your attention
● Please submit your feedback: http://bit.ly/glcfeedback
● Find our further event on our website : https://www.glcnetworks.com/en/
● Like our facebook page: https://www.facebook.com/glcnetworks
● Slide: https://www.slideshare.net/glcnetworks/
● Discord (bahasa indonesia): (https://discord.gg/6MZ3KUHHBX)
● Recording (youtube): https://www.youtube.com/c/GLCNetworks
● Stay tune with our schedule
● Any questions?
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