Download Dynamic Routing Protocols - E Learning UPN Veteran Yogyakarta

Basic static routing and
dynamic routing
Rifki Indra, S.Kom., M.Eng.
http://learning.upnyk.ac.id
Basic Routing Concept
Definisi Static Routing
Static routing adalah salah satu teknik
mentransmisikan/mengirimkan paket data
dari network satu ke network lain melalui
rute yang sudah ditetapkan. (oleh admin)
Basic Router concept
Pastikan paket data yang akan dikirim dengan tujuan yang satu network atau
beda network…?
Define a route and its three key parts
Explain how routes are manually configured to build
routing table
Command routing static
Router#ip route <net id tujuan> <netmask> <ip
next hop>
Router#ip route 0.0.0.0 0.0.0.0 <exit interface>
Advantages and Disadvantages
Advantages of static routing
– It can backup multiple interfaces/networks on
a router
– Easy to configure
– No extra resources are needed
– More secure
Disadvantages of static routing
– Network changes require manual
reconfiguration
– Does not scale well in large topologies
Studi kasus : Bagaimana agar paket
dari PC1 sampai ke PC3?
Pahami dahulu tabel berikut
Device
Port
IP
Gateway
Router 1
S0/0/0 - DCE
192.168.2.1
N/A
Fa0/0
172.16.1.1
N/A
S0/0/0
192.168.2.2
N/A
S0/0/1 - DCE
192.168.1.1
N/A
Fa0/0
172.16.2.1
N/A
S0/0/0
192.168.1.2
N/A
Fa0/0
172.16.3.1
N/A
PC1
-
172.16.1.10
172.16.1.1
PC2
-
172.16.2.10
172.16.2.1
PC3
-
172.16.3.10
172.16.3.1
Router 2
Router 3
Routing Dynamic
Routing dynamis adalah teknik mengirimkan
paket data antar network melalui rute yang
dipilih oleh router dengan
mempertimbangkan best path.
Dynamic Routing Protocols
Function(s) of Dynamic Routing Protocols:
– Dynamically share information between routers.
– Automatically update routing table when
topology changes.
– Determine best path to a destination.
The purpose of a dynamic routing protocol is
to:
– Discover remote networks
– Maintaining up-to-date routing information
– Choosing the best path to destination networks
– Ability to find a new best path if the current
path is no longer available
Components of a routing protocol
– Algorithm
• In the case of a routing protocol algorithms are
used for facilitating routing information and best
path determination
– Routing protocol messages
• These are messages for discovering neighbors and
exchange of routing information
Classifying Routing Protocols
• Dynamic routing protocols are grouped
according to characteristics. Examples
include:
– RIP
– IGRP
– EIGRP
– OSPF
– IS-IS
– BGP
BGP
RIP 1
IGRP
RIP 2
EIGRP
ospf
IS IS
Routing RIP
Routing Information Protocol (RIP) adalah sebuah protokol
routing dinamis yang digunakan dalam jaringan LAN (Local
Area Network) dan WAN (Wide Area Network). Oleh karena
itu protokol ini diklasifikasikan sebagai Interior Gateway
Protocol
(IGP).
Protokol
ini
menggunakan
algoritma Distance-Vector Routing. Pertama kali
didefinisikan dalam RFC 1058 (1988). Protokol ini telah
dikembangkan beberapa kali, sehingga terciptalah RIP Versi
2 (RFC 2453). Kedua versi ini masih digunakan sampai
sekarang, meskipun begitu secara teknis mereka telah
dianggap usang oleh teknik-teknik yang lebih maju,
seperti Open Shortest Path First (OSPF) dan protokol OSI ISIS.
Cara Kerja RIP
1. Host mendengar pada alamat broadcast jika ada update
routing dari gateway.
2. Host akan memeriksa terlebih dahulu routing table lokal jika
menerima update routing .
3. Jika rute belum ada, informasi segera dimasukkan ke routing
table .
4. Jika rute sudah ada, metric yang terkecil akan diambil
sebagai acuan.
5. Rute melalui suatu gateway akan dihapus jika tidak ada
update dari gateway tersebut dalam waktu tertentu.
6. Khusus untuk gateway, RIP akan mengirimkan update
routing pada alamat broadcast di setiap network yang
terhubung
1.
2.
3.
4.
5.
Distance vector routing protocol
Hop count sebagi metric untuk memilih rute, Maximum hop
count 15, hop ke 16 dianggap unreachable
Secara default routing update 30 detik sekali
RIPv1 (classfull routing protocol) tidak mengirimkan subnet
mask pada update
RIPv2 (classless routing protocol) mengirimkan subnet mask
pada update
RIP v1 dan RIP v2
1. RIP v1 tidak mendukung vlsm
2. RIP v1 tidak mengirimkan update routing
dan netmask
3. RIP v1 perbaikan broadcat
4. RIP v2 mendukung vlsm
5. RIP v2 mengirimkan update routing serta
netmask
6. RIP v2 perbaikan multicast
Syntax
Router (config-router)#passive interface fastethernet directly connected
Studi kasus : RIP v1
RIP v2
Syntax :
Untuk masing-masing router berlaku :
Router(config)#router rip
Router(config-router)#version 2
Router(config-router)#network directly connect
Router(config-router)#no auto summary
Studi kasus : RIP v2
Distance Vector Routing Protocols
• Factors used to determine whether to use RIP or EIGRP include
-Network size
-Compatibility between models of routers
-Administrative knowledge
Distance Vector Routing Protocols
Classifying Routing Protocols
Classifying Routing Protocols
• Classful routing protocols
– Do NOT send subnet mask in
routing updates
• Classless routing protocols
– Do send subnet mask in
– routing updates.
Classifying Routing Protocols
Convergence is defined as when all routers’ routing tables are at a state of
consistency
Routing Protocols Metrics
• Metric
– A value used by a routing protocol to determine which routes are
better than others.
Routing Protocols Metrics
• Metrics used in IP routing protocols
– Bandwidth
– Cost
– Delay
– Hop count
– Load
– Reliability
Routing Protocols Metrics
•
•
The Metric Field in the Routing
Table
Metric used for each routing
protocol
– -RIP - hop count
– -IGRP & EIGRP - Bandwidth
(used by default), Delay (used
by default), Load, Reliability
– -IS-IS & OSPF – Cost,
Bandwidth (Cisco’s
implementation)
Routing Protocols Metrics
• Load balancing
– This is the ability of a router to distribute packets among multiple
same cost paths
Administrative Distance of a Route
• Purpose of a metric
– It’s a calculated value used to determine the best path to a
destination
• Purpose of Administrative Distance
– It’s a numeric value that specifies the preference of a particular
route
Administrative Distance of a Route
Identifying the Administrative Distance (AD) in a routing table
– It is the first number in the brackets in the routing table
Administrative Distance of a Route
• Dynamic Routing Protocols
Routing Loops
• Routing loops are
A condition in which a packet
is continuously transmitted
within a series of routers
without ever reaching its
destination.
Routing Loops
• Routing loops may be caused by:
-Incorrectly configured static routes
-Incorrectly configured route redistribution
-Slow convergence
-Incorrectly configured discard routes
• Routing loops can create the following issues
-Excess use of bandwidth
-CPU resources may be strained
-Network convergence is degraded
-Routing updates may be lost or not processed in a timely
manner
Routing Loop Prevention
• Setting a maximum
• Distance Vector routing protocols set a specified metric value to
indicate infinity
Once a router “counts to infinity” it marks the route as
unreachable
Routing Loop Prevention
• Preventing loops with holddown timers
– Holddown timers allow a router to not accept any changes to a
route for a specified period of time.
– Point of using holddown timers
 Allows routing updates to propagate through network with the
most current information.
Routing Loop Prevention
• The Split Horizon Rule is used to prevent routing loops
• Split Horizon rule:
A router should not advertise a network through the interface
from which the update came.
Routing Loop Prevention
• Split horizon with poison reverse
The rule states that once a
router learns of an unreachable
route through an interface,
advertise it as unreachable back
through the same interface
Routing Loop Prevention
• IP & TTL
– Purpose of the TTL field
The TTL field is found in an IP header and is used to prevent
packets from endlessly traveling on a network
• How the TTL field works
TTL field contains a numeric value.
The numeric value is decreased by one by every router on the
route to the destination. If numeric value reaches 0 then Packet is
discarded.
Link-State Routing
Dikjstra’s algorithm also known as the shortest path first (SPF) algorithm
Link-State Routing
• The shortest path to a destination is not necessarily the path with the
least number of hops
Link-State Routing
Link-State Routing Process
• How routers using Link State Routing Protocols reach convergence
-Each routers learns about its own directly connected networks
-Link state routers exchange hello packet to “meet” other directly
connected link state routers.
-Each router builds its own Link State Packet (LSP) which includes
information about neighbors such as neighbor ID, link type, &
bandwidth.
-After the LSP is created the router floods it to all neighbors who then
store the information and then forward it until all routers have the
same information.
-Once all the routers have received all the LSPs, the routers then
construct a topological map of the network which is used to
determine the best routes to a destination
Link-State Routing
Sending Hello Packets to
Neighbors
• Connected interfaces that are using the
same link state routing protocols will
exchange hello packets.
• Once routers learn it has neighbors they
form an adjacency
-2 adjacent neighbors will
exchange hello packets
-These packets will serve as a
keep alive function
Link-State Routing
Constructing a link state data base
• Routers use a database to construct a topology map of the network
Link-State Routing
Link-State Routing
• Once the SPF algorithm has determined the shortest path routes, these
routes are placed in the routing table.