In this webinar, we will discuss about the basic concept of routing, try to understand how the router work, how the routing table is used to forward packets, and how to implement them with mikrotik router. we review some prior knowledge before. after attending this webinar, we expect you understand how the packet is forwarded on router.

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Routing fundamentals
with Mikrotik
GLC webinar, 1 December 2016
Achmad Mardiansyah
achmad@glcnetworks.com
GLC Networks, Indonesia

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Agenda
● Introduction
● Layer 3 concept
● Routing
● Demo
● Q & A
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What is GLC?
● Garda Lintas Cakrawala (www.glcnetworks.com)
● An Indonesian company
● Located in Bandung
● Areas: Training, IT Consulting
● Mikrotik Certified Training Partner
● Mikrotik Certified Consultant
● Mikrotik distributor
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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: every 2 weeks
● Irregular schedule: as needed
● Checking schedule:
http://www.glcnetworks.com/main/sc
hedule
● 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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Trainer Introduction
● Name: Achmad Mardiansyah
● Base: bandung, Indonesia
● Linux user since ’99
● Mikrotik user since 2007
● Certified Trainer (MTCNA/RE/WE/UME/INE/TCE)
● Mikrotik Certified Consultant
● Work: Telco engineer, Sysadmin, PHP programmer,
and Lecturer
● Personal website: http://achmad.glcnetworks.com
● More info:
http://au.linkedin.com/in/achmadmardiansyah
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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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What is Mikrotik?
● Name of a company
● A brand
● A program (e.g. mikrotik academy)
● Headquarter: Riga, Latvia
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What are mikrotik products?
● Router OS
○ The OS. Specialized for networking
○ Website: www.mikrotik.com/download
● RouterBoard
○ The hardware
○ RouterOS installed
○ Website: www.routerboard.com
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What Router OS can do?
● Go to www.mikrotik.com
○ Download: what_is_routeros.pdf
○ Download: product catalog
○ Download: newsletter
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What are Mikrotik training & certifications?
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Certificate validity is 3 years

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Layer 3 concept
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Layer 3
● Logical address
● 2 versions: IPv4 (our focus) and IPv6
● IPv4 32 bit long
● Consist of network part & host part
● Can be class based IP address (without subnet)
● Now it is classless IP address -> VLSM (variable
length subnet mask)
● CIDR (classless inter domain routing)
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IP spec (RFC 791)
● Defined long time ago (what 1981?)
● Defines how the IP header looks like
● Still used up to know
● New version -> IPv6
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How the layer 3 address look like?
● IPv4 address is 32 bit
● Written in binary
● Displayed to human in decimal every 8 bit (octet).
● Has 2 parts: network part and host part
● Like a phone number 0812 XXXXXXXX -> hierarchical
● All devices in the network will have same network address
● First and last address cannot be used (for network id and broadcast id)
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Network part host part

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Layer 3 connection and addressing
● Devices that uses layer 3 information: router and host
● All devices must have a layer 3 address
● address is hierarchical
○ Network part (e.g. 192.168.0.2/26 -> the first 26 bit of all host in the network will be
the same) -> show the grouping identity
○ Host part
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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

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What is VLSM?
● Variable-Length Subnet Masking (VLSM)
● Can divide an IP address block into subnets of different sizes using / (slash)
notation
● Solution the in efficient of classful IP address (fixed length). No more class A,
class B, Class C -> pleeease dont say this classes anymore
● making it possible to create subnets with very different host counts without
wasting large numbers of addresses.
● RFC: 1878 (1995)
● Basis for CIDR
● Example: 23.45.0.0/16
○ 23.45.0.0/25
○ 23.45.0.128/25
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VLSM RFC
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What is CIDR?
● CIDR: Classless Inter-Domain Routing (sometimes is called supernetting)
● CIDR solves problem of wasted address space by providing a new and more
flexible way to specify network addresses in routers (using slash as notation)
● allow flexible allocation of Internet Protocol (IP) addresses.
● Replaces classfull network (class A,B,C,D). Please dont ever mention this
anymore...
● CIDR lets a routing table entry represent an aggregation of networks that exist
in the forward path
● Each IP address has a network prefix that identifies either one or several
network gateways.
● RFC: 1519
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CIDR RFC
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Routing
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What is 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
0.0.0.0/0 192.168.0.3

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When router receive a packet…
(setup priority on routing table)
● Router will analyse the destination IP address
● Router will rearrange the routing entry and put priority
○ Longest prefix wins
○ Lowest distance wins
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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
0.0.0.0/0 192.168.0.3
destination gateway
192.168.16.3/32 192.168.0.2
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
0.0.0.0/0 192.168.0.3

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How the routing table works (R1)?
● It works like a firewall: match and action
● You should think in binary to understand how it works
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destination gateway
192.168.16.3/32
11000000 10101000 00001000 00000011
192.168.0.2
192.168.0.0/26
11000000 10101000 00000000 00
direct
192.168.1.0/24
11000000 10101000 00000001
direct
192.168.2.0/24
11000000 10101000 00000010
192.168.0.2
192.168.3.0/24
11000000 10101000 00000011
192.168.0.3
0.0.0.0/0 192.168.0.3

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A packet arrived… (part 1)
Destination IP address of the packet is 192.168.16.3, which gateway do we use?
A: 192.168.16.3 = (11000000 10101000 00001000 00000011)
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destination gateway
192.168.16.3/32
11000000 10101000 00001000 00000011
192.168.0.2
192.168.0.0/26
11000000 10101000 00000000 00
direct
192.168.1.0/24
11000000 10101000 00000001
direct
192.168.2.0/24
11000000 10101000 00000010
192.168.0.2
192.168.3.0/24
11000000 10101000 00000011
192.168.0.3
0.0.0.0/0 192.168.0.3
MATCH

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A packet arrived… (part 2)
Destination IP address of the packet is 192.168.2.6, which gateway do we use?
A: 192.168.2.6 = (11000000 10101000 00000010 00000110)
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destination gateway
192.168.16.3/32
11000000 10101000 00001000 00000011
192.168.0.2
192.168.0.0/26
11000000 10101000 00000000 00
direct
192.168.1.0/24
11000000 10101000 00000001
direct
192.168.2.0/24
11000000 10101000 00000010
192.168.0.2
192.168.3.0/24
11000000 10101000 00000011
192.168.0.3
0.0.0.0/0 192.168.0.3
NOT MATCH
NOT MATCH
NOT MATCH
MATCH

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A packet arrived… (part 3)
Destination IP address of the packet is 192.168.8.6, which gateway do we use?
A: 192.168.8.6 = (11000000 10101000 00001000 00000110)
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destination gateway
192.168.16.3/32
11000000 10101000 00001000 00000011
192.168.0.2
192.168.0.0/26
11000000 10101000 00000000 00
direct
192.168.1.0/24
11000000 10101000 00000001
direct
192.168.2.0/24
11000000 10101000 00000010
192.168.0.2
192.168.3.0/24
11000000 10101000 00000011
192.168.0.3
0.0.0.0/0 192.168.0.3
NOT MATCH
NOT MATCH
NOT MATCH
MATCH
NOT MATCH
NOT MATCH

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Static routing
● Entries on routing table is created
manually
● Admin must manage routing table
in all routers
● Admin have full control
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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
0.0.0.0/0 192.168.0.3

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Dynamic routing
● Entries on routing table is created
automatically using routing protocol
(RIP, OSPF, BGP)
● Admin must have a good
knowledge about routing protocol
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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
0.0.0.0/0 192.168.0.3

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DEMO
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Mikrotik routing table
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QA
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End of slides
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