SlideShare a Scribd company logo
1 of 45
Download to read offline
Link-State Routing
Protocols - OSPF

Routing Protocols and Concepts – Chapter 10 & 11

ITE I Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

1
Objectives


Describe the basic features & concepts of link-state
routing protocols.



List the benefits and requirements of link-state routing
protocols.



Describe the background and basic features of OSPF



Identify and apply the basic OSPF configuration
commands



Describe, modify and calculate the metric used by
OSPF



Describe the Designated Router/Backup Designated
Router (DR/BDR) election process

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

2
Link-State Routing
 Link state routing protocols
-Also

known as shortest path first algorithms

-These protocols built around Dijkstra’s
SPF

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

3
Link-State Routing
Dikjstra’s algorithm also known as the shortest path first
(SPF) algorithm

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

4
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
ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

5
Link-State Routing
Constructing a link state data base
 Routers use a database to construct a topology map of
the network

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

6
Link-State Routing
Shortest Path First (SPF) Tree
 Building a portion of the SPF tree
Process begins by examining R2’s LSP information
-R1 ignores 1st LSP
Reason: R1 already knows it’s connected to R2

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

7
Link-State Routing
 Determining the shortest path
The shortest path to a destination determined by adding the
costs & finding the lowest cost

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

8
Link-State Routing
 Once the SPF algorithm has determined the shortest
path routes, these routes are placed in the routing
table.

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

9
Link-State Routing Protocols
Advantages of a Link-State Routing Protocol

Routing
protocol

Builds
Topological
map

Router can
independently
determine the
shortest path to
every network.

Distance
vector

No

Link State

Yes

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Convergence

A periodic/
event driven
routing updates

Use
of
LSP

No

Slow

Generally No

No

Yes

Fast

Generally Yes

Yes

Cisco Public

10
Link-State Routing Protocols
Requirements for using a link state routing protocol
 Memory requirements
Typically link state routing protocols use more
memory
 Processing Requirements
More CPU processing is required of link state
routing protocols
 Bandwidth Requirements
Initial startup of link state routing protocols can
consume lots of bandwidth

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

11
Introduction to OSPF
OSPF Message Encapsulation
 OSPF packet type
There exist 5 types
 OSPF packet header
Contains - Router ID and
area ID and Type code for
OSPF packet type
 IP packet header
Contains - Source IP
address, Destination IP
address, & Protocol field
set to 89

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

12
Introduction to OSPF
OSPF Message Encapsulation
 Data link frame header
Contains - Source MAC address and Destination
MAC address

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

13
Introduction to OSPF
OSPF Packet Types
OSPF PACKET TYPE

DESCRIPTION

1: HELLO

Discovers neighbors & builds
ADJACENCY W/ NEIGHBORS

2: DATABASE
DESCRIPTION

Checks for database
synchronization between routers

3: LINK STATE
REQUEST

REQUESTS SPECIFIC LINK STATE
DATABASE information from router
to router

4: LINK STATE
UPDATE

TRANSPORTS LINK STATE records

5: LINK STATE
ACKNOWLEDGEMENT

ACKNOWLEDGES RECEIPT OF
other packet types

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

14
Introduction to OSPF
Hello Protocol
 OSPF Hello Packet
–Purpose of Hello Packet
 discover OSPF neighbors & establish adjacencies
 advertise guidelines on which routers must agree to
become neighbors
 used by multi-access networks to elect a designated
router and a backup designated router

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

15
Introduction to OSPF
 Hello Packets continued
Contents of a Hello Packet
router ID of transmitting router

 OSPF Hello Intervals
–Usually multicast (224.0.0.5)
–Sent every 30 seconds for NBMA segments

 OSPF Dead Intervals
–This is the time that must transpire
before the neighbor is considered
down
–Default time is 4 times
the hello interval

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

16
Introduction to OSPF
 Hello protocol packets contain information that is used
in electing
-Designated Router (DR)
 DR is responsible for updating all other OSPF routers
-Backup Designated Router (BDR)
 This router takes over DR’s responsibilities if DR fails

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

17
Introduction to OSPF
OSPF Link-state Updates
 Purpose of a Link State Update (LSU)
Used to deliver link state advertisements

 Purpose of a Link State Advertisement (LSA)
Contains information about neighbors & path costs

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

18
Introduction to OSPF
OSPF Algorithm
 OSPF routers build &
maintain link-state
database containing LSA
received from other routers
–Information found in
database is utilized upon
execution of Dijkstra SPF
algorithm
–SPF algorithm used to
create SPF tree
–SPF tree used to populate
routing table

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

19
Introduction to OSPF
 OSPF Authentication
–Purpose is to encrypt & authenticate routing
information
–This is an interface specific configuration
–Routers will only accept routing information from
other routers that have been configured with the
same password or authentication information

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

20
Basic OSPF Configuration
 OSPF network command
-Requires entering: network address
wildcard mask - the inverse of the subnet
mask
area-id - area-id refers to the OSPF area.
OSPF area is a group of routers that
share link state information
-Example: Router(config-router)#network network-address
wildcard-ask area area-id

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

21
Basic OSPF Configuration
 Router ID
–This is an IP address used to identify a router
–3 criteria for deriving the router ID
Use IP address configured with OSPF router-id command
-Takes precedence over loopback and physical interface
addresses
If router-id command not used then router chooses highest
IP address of any loopback interfaces
If no loopback interfaces are configured then the highest IP
address on any active interface is used

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

22
Basic OSPF Configuration
OSPF Router ID
 Router ID & Loopback addresses
-Highest loopback address will be used as router ID if router-id
command isn’t used
-Advantage of using loopback address
the loopback interface cannot fail  OSPF stability

 The OSPF router-id command
–Introduced in IOS 12.0
–Command syntax
Router(config)#router ospf process-id
Router(config-router)#router-id ip-address

 Modifying the Router ID
–Use the command Router#clear ip ospf process
ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

23
Basic OSPF Configuration
Verifying OSPF
 Use the show ip ospf command to verify & trouble
shoot OSPF networks
Command will display the following:
 Neighbor adjacency
-No adjacency indicated by Neighboring router’s Router ID is not displayed
A state of full is not displayed
-Consequence of no adjacencyNo link state information exchanged
Inaccurate SPF trees & routing tables

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

24
OSPF Metric
 OSPF uses cost as the metric for determining the
best route
-The best route will have the lowest cost
-Cost is based on bandwidth of an interface
Cost is calculated using the formula

108 / bandwidth
-Reference bandwidth
defaults to 100Mbps
can be modified using
auto-cost reference-bandwidth command

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

25
OSPF Metric
 COST of an OSPF route
Is the accumulated value from one router to the next

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

26
OSPF Metric
 Usually the actual speed of a link is different than the
default bandwidth
–This makes it imperative that the bandwidth value reflects
link’s actual speed
Reason: so routing table has best path information

 The show interface command will display interface’s
bandwidth
-Most serial link default to 1.544Mbps

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

27
Basic OSPF Configuration
Modifying the Cost of a link
 Both sides of a serial link should be configured with the
same bandwidth
–Commands used to modify bandwidth value
Bandwidth command
–Example: Router(config-if)#bandwidth bandwidth-kbps
ip ospf cost command – allows you to directly specify
interface cost
-Example:R1(config)#interface serial 0/0/0
R1(config-if)#ip ospf cost 1562

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

28
Basic OSPF Configuration
Modifying the Cost of the link
 Difference between bandwidth command & the ip ospf
cost command
–Ip ospf cost command
Sets cost to a specific value
–Bandwidth command
Link cost is calculated

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

29
OSPF and Multi-access Networks
Challenges in Multi-access Networks
 OSPF defines five network types:
–Point-to-point
–Broadcast Multiaccess
–Nonbroadcast Multiaccess (NBMA)
–Point-to-multipoint
–Virtual links

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

30
OSPF in Multi-access Networks
 2 challenges presented by multi-access networks
–Multiple adjacencies
–Extensive LSA flooding

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

31
OSPF in Multi-access Networks
 Extensive flooding of LSAs
For every LSA sent out there must be an acknowledgement of
receipt sent back to transmitting router.
consequence: lots of bandwidth consumed and chaotic traffic

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

32
OSPF in Multi-access Networks
 Solution to LSA flooding issue
is the use of
–Designated router (DR)
–Backup designated router (BDR)

 DR & BDR selection
–Routers are elected to send &
receive LSA

 Sending & Receiving LSA
–DRothers send LSAs via
multicast 224.0.0.6 to DR & BDR
–DR forward LSA via multicast
address 224.0.0.5 to all other
routers
ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

33
OSPF in Multi-access Networks
DR/BDR Election Process
 DR/BDR elections DO NOT occur in point to point
networks

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

34
OSPF in Multi-access Networks
 DR/BDR elections will take place on multi-access
networks as shown below

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

35
OSPF in Multi-access Networks
 Criteria for getting elected DR/BDR
1. DR: Router with the highest OSPF
interface priority.
2. BDR: Router with the second highest
OSPF interface priority.
3. If OSPF interface priorities are equal, the
highest router ID is used to break the tie.

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

36
OSPF in Multi-access Networks
 Timing of DR/BDR Election
–Occurs as soon as 1st router has its interface enabled on multiaccess network
When a DR is elected it remains as the DR until one of the
following occurs
-The DR fails.
-The OSPF process on the DR fails.
-The multiaccess interface on the DR fails.

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

37
OSPF in Multi-access Networks
 Manipulating the election process
-If you want to influence the election of DR & BDR then do one
of the following
Boot up the DR first, followed by the BDR, and then boot all
other routers,
OR
Shut down the interface on all routers, followed by a no
shutdown on the DR, then the BDR, and then all other
routers.

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

38
OSPF in Multi-access Networks
OSPF Interface Priority
 Manipulating the DR/BDR election process continued
–Use the ip ospf priority interface command.
–Example:Router(config-if)#ip ospf priority {0 - 255}
Priority number range 0 to 255
–0 means the router cannot become the DR or BDR
–1 is the default priority value

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

39
More OSPF Configuration
Redistributing an OSPF Default Route
 Topology includes a link to ISP
–Router connected to ISP
Called an autonomous system border router
Used to propagate a default route
–Example of static default route
R1(config)#ip route 0.0.0.0 0.0.0.0
loopback 1
–Requires the use of the default-information originate
command
–Example of default-information originate command
R1(config-router)#default-information
originate
ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

40
More OSPF Configuration
Fine-Tuning OSPF
 Modifying OSPF timers
–Reason to modify timers
Faster detection of network failures
–Manually modifying Hello & Dead intervals
Router(config-if)#ip ospf hello-interval seconds
Router(config-if)#ip ospf dead-interval seconds
–Point to be made
Hello & Dead intervals must be the same between
neighbors

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

41
Summary
 Link State Routing protocols are also known as Shortest
Path First protocols
 Summarizing the link state process
-Routers 1ST learn of directly connected networks
-Routers then say “hello” to neighbors
-Routers then build link state packets
-Routers then flood LSPs to all neighbors
-Routers use LSP database to build a network topology
map & calculate the best path to each destination

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

42
Summary
 Link
An interface on the router
 Link State
Information about an interface such as
-IP address
-Subnet mask
-Type of network
-Cost associated with link
-Neighboring routers on the link
 Link State Packets
-After initial flooding, additional LSP are sent out
-when a change in topology occurs
 Examples of link state routing protocols
-Open shortest path first
-IS-IS
ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

43
Summary
 RFC 2328 describes OSPF link state concepts and
operations
 OSPF Characteristics
–A commonly deployed link state routing protocol
–Employs DRs & BDRs on multi-access networks
DRs & BDRs are elected
DR & BDRs are used to transmit and receive LSAs
–Uses 5 packet types:
1: HELLO
2: DATABASE DESCRIPTION
3: LINK STATE REQUEST
4: LINK STATE UPDATE
5: LINK STATE ACKNOWLEDGEMENT

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

44
Summary
 OSPF Characteristics
–Metric = cost
Lowest cost = best path

 Configuration
–Enable OSPF on a router using the following command
R1(config)#router ospf process-id
–use the network command to define which interfaces will
participate in a given OSPF process
Router(config-router)#network network-address
wildcard-mask area area-id

ITE 1 Chapter 6

© 2006 Cisco Systems, Inc. All rights reserved.

Cisco Public

45

More Related Content

What's hot

CCNA Exploration 2 - Chapter 10
CCNA Exploration 2 - Chapter 10CCNA Exploration 2 - Chapter 10
CCNA Exploration 2 - Chapter 10Irsandi Hasan
 
Exploration routing chapter_10
Exploration routing chapter_10Exploration routing chapter_10
Exploration routing chapter_10Joshua Torres
 
Exploration routing chapter_11
Exploration routing chapter_11Exploration routing chapter_11
Exploration routing chapter_11Joshua Torres
 
Exploration routing chapter_9
Exploration routing chapter_9Exploration routing chapter_9
Exploration routing chapter_9Joshua Torres
 
CCNA Exploration 2 - Chapter 4
CCNA Exploration 2 - Chapter 4CCNA Exploration 2 - Chapter 4
CCNA Exploration 2 - Chapter 4Irsandi Hasan
 
CCNA Exploration 2 - Chapter 6
CCNA Exploration 2 - Chapter 6CCNA Exploration 2 - Chapter 6
CCNA Exploration 2 - Chapter 6Irsandi Hasan
 
CCNAS :Multi Area OSPF
CCNAS :Multi Area OSPFCCNAS :Multi Area OSPF
CCNAS :Multi Area OSPFrooree29
 
CCNA Exploration 2 - Chapter 9
CCNA Exploration 2 - Chapter 9CCNA Exploration 2 - Chapter 9
CCNA Exploration 2 - Chapter 9Irsandi Hasan
 
Exploration routing chapter_4
Exploration routing chapter_4Exploration routing chapter_4
Exploration routing chapter_4Joshua Torres
 
Exploration routing chapter_6
Exploration routing chapter_6Exploration routing chapter_6
Exploration routing chapter_6Joshua Torres
 
Exploration routing chapter_8
Exploration routing chapter_8Exploration routing chapter_8
Exploration routing chapter_8Joshua Torres
 
CCNA Exploration 2 - Chapter 7
CCNA Exploration 2 - Chapter 7CCNA Exploration 2 - Chapter 7
CCNA Exploration 2 - Chapter 7Irsandi Hasan
 
CCNAv5 - S2: Chapter 6 Static Routing
CCNAv5 - S2: Chapter 6 Static RoutingCCNAv5 - S2: Chapter 6 Static Routing
CCNAv5 - S2: Chapter 6 Static RoutingVuz Dở Hơi
 
CCNA 2 Routing and Switching v5.0 Chapter 6
CCNA 2 Routing and Switching v5.0 Chapter 6CCNA 2 Routing and Switching v5.0 Chapter 6
CCNA 2 Routing and Switching v5.0 Chapter 6Nil Menon
 
Chapter 15 : routing concepts
Chapter 15 : routing conceptsChapter 15 : routing concepts
Chapter 15 : routing conceptsteknetir
 
CCNA3 Verson6 Chapter9
CCNA3 Verson6 Chapter9CCNA3 Verson6 Chapter9
CCNA3 Verson6 Chapter9Chaing Ravuth
 
CCNA Exploration 2 - Chapter 2
CCNA Exploration 2 - Chapter 2CCNA Exploration 2 - Chapter 2
CCNA Exploration 2 - Chapter 2Irsandi Hasan
 
CCNA Exploration 4 - Chapter 7
CCNA Exploration 4 - Chapter 7CCNA Exploration 4 - Chapter 7
CCNA Exploration 4 - Chapter 7Irsandi Hasan
 
Exploration routing chapter_3
Exploration routing chapter_3Exploration routing chapter_3
Exploration routing chapter_3Joshua Torres
 

What's hot (20)

CCNA Exploration 2 - Chapter 10
CCNA Exploration 2 - Chapter 10CCNA Exploration 2 - Chapter 10
CCNA Exploration 2 - Chapter 10
 
Exploration routing chapter_10
Exploration routing chapter_10Exploration routing chapter_10
Exploration routing chapter_10
 
Exploration routing chapter_11
Exploration routing chapter_11Exploration routing chapter_11
Exploration routing chapter_11
 
Exploration routing chapter_9
Exploration routing chapter_9Exploration routing chapter_9
Exploration routing chapter_9
 
CCNA Exploration 2 - Chapter 4
CCNA Exploration 2 - Chapter 4CCNA Exploration 2 - Chapter 4
CCNA Exploration 2 - Chapter 4
 
CCNA Exploration 2 - Chapter 6
CCNA Exploration 2 - Chapter 6CCNA Exploration 2 - Chapter 6
CCNA Exploration 2 - Chapter 6
 
CCNAS :Multi Area OSPF
CCNAS :Multi Area OSPFCCNAS :Multi Area OSPF
CCNAS :Multi Area OSPF
 
CCNA Exploration 2 - Chapter 9
CCNA Exploration 2 - Chapter 9CCNA Exploration 2 - Chapter 9
CCNA Exploration 2 - Chapter 9
 
Exploration routing chapter_4
Exploration routing chapter_4Exploration routing chapter_4
Exploration routing chapter_4
 
Exploration routing chapter_6
Exploration routing chapter_6Exploration routing chapter_6
Exploration routing chapter_6
 
Exploration routing chapter_8
Exploration routing chapter_8Exploration routing chapter_8
Exploration routing chapter_8
 
CCNA Exploration 2 - Chapter 7
CCNA Exploration 2 - Chapter 7CCNA Exploration 2 - Chapter 7
CCNA Exploration 2 - Chapter 7
 
CCNAv5 - S2: Chapter 6 Static Routing
CCNAv5 - S2: Chapter 6 Static RoutingCCNAv5 - S2: Chapter 6 Static Routing
CCNAv5 - S2: Chapter 6 Static Routing
 
CCNA 2 Routing and Switching v5.0 Chapter 6
CCNA 2 Routing and Switching v5.0 Chapter 6CCNA 2 Routing and Switching v5.0 Chapter 6
CCNA 2 Routing and Switching v5.0 Chapter 6
 
Ospf
OspfOspf
Ospf
 
Chapter 15 : routing concepts
Chapter 15 : routing conceptsChapter 15 : routing concepts
Chapter 15 : routing concepts
 
CCNA3 Verson6 Chapter9
CCNA3 Verson6 Chapter9CCNA3 Verson6 Chapter9
CCNA3 Verson6 Chapter9
 
CCNA Exploration 2 - Chapter 2
CCNA Exploration 2 - Chapter 2CCNA Exploration 2 - Chapter 2
CCNA Exploration 2 - Chapter 2
 
CCNA Exploration 4 - Chapter 7
CCNA Exploration 4 - Chapter 7CCNA Exploration 4 - Chapter 7
CCNA Exploration 4 - Chapter 7
 
Exploration routing chapter_3
Exploration routing chapter_3Exploration routing chapter_3
Exploration routing chapter_3
 

Viewers also liked

Open Shortest Path First
Open Shortest Path FirstOpen Shortest Path First
Open Shortest Path FirstKashif Latif
 
EIGRP NXOS vs IOS Differences
EIGRP NXOS vs IOS DifferencesEIGRP NXOS vs IOS Differences
EIGRP NXOS vs IOS DifferencesJohn Berry
 
Exploration Routing Chapter 7
Exploration Routing Chapter 7Exploration Routing Chapter 7
Exploration Routing Chapter 7jayhawkins
 
Manual cisco 2950
Manual cisco 2950Manual cisco 2950
Manual cisco 2950liviuisr
 
Mesopotamia ciudades de estado
Mesopotamia ciudades de estadoMesopotamia ciudades de estado
Mesopotamia ciudades de estadovanessavergara18
 
Asure one spark (3)
Asure one spark (3)Asure one spark (3)
Asure one spark (3)Bizapity
 
Y'ems Group's Social Networking for Organizations Ver 1.0
Y'ems Group's Social Networking for Organizations Ver 1.0Y'ems Group's Social Networking for Organizations Ver 1.0
Y'ems Group's Social Networking for Organizations Ver 1.0Y'ems GroupCo
 
01 a-salinan-permendikbud-no-54-tahun-2013-ttg-skl
01 a-salinan-permendikbud-no-54-tahun-2013-ttg-skl01 a-salinan-permendikbud-no-54-tahun-2013-ttg-skl
01 a-salinan-permendikbud-no-54-tahun-2013-ttg-sklkb candipuro
 
How consumers are using the smartphones
How consumers are using the smartphonesHow consumers are using the smartphones
How consumers are using the smartphonesCreadsmedia
 
Social Media and (Urban) Social Protest: The Brazilian Experience
Social Media and (Urban) Social Protest: The Brazilian ExperienceSocial Media and (Urban) Social Protest: The Brazilian Experience
Social Media and (Urban) Social Protest: The Brazilian ExperienceAnita Breuer
 
We Create KC Year 3
We Create KC Year 3We Create KC Year 3
We Create KC Year 3Sarah Mote
 

Viewers also liked (20)

Protocole OSPF
Protocole OSPFProtocole OSPF
Protocole OSPF
 
Open Shortest Path First
Open Shortest Path FirstOpen Shortest Path First
Open Shortest Path First
 
Ospf
OspfOspf
Ospf
 
EIGRP NXOS vs IOS Differences
EIGRP NXOS vs IOS DifferencesEIGRP NXOS vs IOS Differences
EIGRP NXOS vs IOS Differences
 
OSPF Virtual Link
OSPF Virtual LinkOSPF Virtual Link
OSPF Virtual Link
 
Exploration Routing Chapter 7
Exploration Routing Chapter 7Exploration Routing Chapter 7
Exploration Routing Chapter 7
 
Ospf
 Ospf Ospf
Ospf
 
Manual cisco 2950
Manual cisco 2950Manual cisco 2950
Manual cisco 2950
 
Ccna day3
Ccna day3Ccna day3
Ccna day3
 
Mesopotamia ciudades de estado
Mesopotamia ciudades de estadoMesopotamia ciudades de estado
Mesopotamia ciudades de estado
 
Asure one spark (3)
Asure one spark (3)Asure one spark (3)
Asure one spark (3)
 
Actividad 7
Actividad 7Actividad 7
Actividad 7
 
Y'ems Group's Social Networking for Organizations Ver 1.0
Y'ems Group's Social Networking for Organizations Ver 1.0Y'ems Group's Social Networking for Organizations Ver 1.0
Y'ems Group's Social Networking for Organizations Ver 1.0
 
E1S
E1SE1S
E1S
 
01 a-salinan-permendikbud-no-54-tahun-2013-ttg-skl
01 a-salinan-permendikbud-no-54-tahun-2013-ttg-skl01 a-salinan-permendikbud-no-54-tahun-2013-ttg-skl
01 a-salinan-permendikbud-no-54-tahun-2013-ttg-skl
 
How consumers are using the smartphones
How consumers are using the smartphonesHow consumers are using the smartphones
How consumers are using the smartphones
 
Social Media and (Urban) Social Protest: The Brazilian Experience
Social Media and (Urban) Social Protest: The Brazilian ExperienceSocial Media and (Urban) Social Protest: The Brazilian Experience
Social Media and (Urban) Social Protest: The Brazilian Experience
 
Presentation1
Presentation1Presentation1
Presentation1
 
MPW - Management of self
MPW - Management of selfMPW - Management of self
MPW - Management of self
 
We Create KC Year 3
We Create KC Year 3We Create KC Year 3
We Create KC Year 3
 

Similar to Exploration routing chapter 10 & 11

Week9(1)
Week9(1)Week9(1)
Week9(1)trayyoo
 
CCNA Discovery 3 - Chapter 6
CCNA Discovery 3 - Chapter 6CCNA Discovery 3 - Chapter 6
CCNA Discovery 3 - Chapter 6Irsandi Hasan
 
CCNA 2 Routing and Switching v5.0 Chapter 8
CCNA 2 Routing and Switching v5.0 Chapter 8CCNA 2 Routing and Switching v5.0 Chapter 8
CCNA 2 Routing and Switching v5.0 Chapter 8Nil Menon
 
CCNAv5 - S3: Chapter6 Multiarea OSPF
CCNAv5 - S3: Chapter6 Multiarea OSPFCCNAv5 - S3: Chapter6 Multiarea OSPF
CCNAv5 - S3: Chapter6 Multiarea OSPFVuz Dở Hơi
 
CCNAv5 - S2: Chapter 8 single area ospf
CCNAv5 - S2: Chapter 8 single area ospfCCNAv5 - S2: Chapter 8 single area ospf
CCNAv5 - S2: Chapter 8 single area ospfVuz Dở Hơi
 
Chapter 08 - Single-Area OSPF
Chapter 08 - Single-Area OSPFChapter 08 - Single-Area OSPF
Chapter 08 - Single-Area OSPFYaser Rahmati
 
ENSA_Module_1.pptx
ENSA_Module_1.pptxENSA_Module_1.pptx
ENSA_Module_1.pptxserieux1
 
Chapter 19 : single-area ospf
Chapter 19 : single-area ospfChapter 19 : single-area ospf
Chapter 19 : single-area ospfteknetir
 
RS_InstructorPPT_Chapter8.pptx
RS_InstructorPPT_Chapter8.pptxRS_InstructorPPT_Chapter8.pptx
RS_InstructorPPT_Chapter8.pptxjagali
 
CCNA Exploration 2 - Chapter 1
CCNA Exploration 2 - Chapter 1CCNA Exploration 2 - Chapter 1
CCNA Exploration 2 - Chapter 1Irsandi Hasan
 
Week3 part 2
Week3  part 2Week3  part 2
Week3 part 2trayyoo
 
Exploration routing chapter_1
Exploration routing chapter_1Exploration routing chapter_1
Exploration routing chapter_1Joshua Torres
 
Chapter5 adjust and troubleshoot single area ospf
Chapter5 adjust and troubleshoot single area ospfChapter5 adjust and troubleshoot single area ospf
Chapter5 adjust and troubleshoot single area ospfVuz Dở Hơi
 
ENSA_Module_1.pptx
ENSA_Module_1.pptxENSA_Module_1.pptx
ENSA_Module_1.pptxrnamboori1
 

Similar to Exploration routing chapter 10 & 11 (20)

Week9(1)
Week9(1)Week9(1)
Week9(1)
 
CCNA Discovery 3 - Chapter 6
CCNA Discovery 3 - Chapter 6CCNA Discovery 3 - Chapter 6
CCNA Discovery 3 - Chapter 6
 
CCNP ROUTE V7 CH3
CCNP ROUTE V7 CH3CCNP ROUTE V7 CH3
CCNP ROUTE V7 CH3
 
CCNA 2 Routing and Switching v5.0 Chapter 8
CCNA 2 Routing and Switching v5.0 Chapter 8CCNA 2 Routing and Switching v5.0 Chapter 8
CCNA 2 Routing and Switching v5.0 Chapter 8
 
CCNAv5 - S3: Chapter6 Multiarea OSPF
CCNAv5 - S3: Chapter6 Multiarea OSPFCCNAv5 - S3: Chapter6 Multiarea OSPF
CCNAv5 - S3: Chapter6 Multiarea OSPF
 
CCNAv5 - S2: Chapter 8 single area ospf
CCNAv5 - S2: Chapter 8 single area ospfCCNAv5 - S2: Chapter 8 single area ospf
CCNAv5 - S2: Chapter 8 single area ospf
 
Chapter 08 - Single-Area OSPF
Chapter 08 - Single-Area OSPFChapter 08 - Single-Area OSPF
Chapter 08 - Single-Area OSPF
 
ENSA_Module_1.pptx
ENSA_Module_1.pptxENSA_Module_1.pptx
ENSA_Module_1.pptx
 
Chapter 19 : single-area ospf
Chapter 19 : single-area ospfChapter 19 : single-area ospf
Chapter 19 : single-area ospf
 
RS_InstructorPPT_Chapter8.pptx
RS_InstructorPPT_Chapter8.pptxRS_InstructorPPT_Chapter8.pptx
RS_InstructorPPT_Chapter8.pptx
 
CCNA Exploration 2 - Chapter 1
CCNA Exploration 2 - Chapter 1CCNA Exploration 2 - Chapter 1
CCNA Exploration 2 - Chapter 1
 
Week3 part 2
Week3  part 2Week3  part 2
Week3 part 2
 
Exploration routing chapter_1
Exploration routing chapter_1Exploration routing chapter_1
Exploration routing chapter_1
 
Cisco ospf
Cisco ospf Cisco ospf
Cisco ospf
 
Link state protocols.ppt
Link state protocols.pptLink state protocols.ppt
Link state protocols.ppt
 
Chapter5 adjust and troubleshoot single area ospf
Chapter5 adjust and troubleshoot single area ospfChapter5 adjust and troubleshoot single area ospf
Chapter5 adjust and troubleshoot single area ospf
 
Cisco ospf
Cisco ospf Cisco ospf
Cisco ospf
 
Routing Protocols
Routing ProtocolsRouting Protocols
Routing Protocols
 
CSC427_Week_11.pdf
CSC427_Week_11.pdfCSC427_Week_11.pdf
CSC427_Week_11.pdf
 
ENSA_Module_1.pptx
ENSA_Module_1.pptxENSA_Module_1.pptx
ENSA_Module_1.pptx
 

More from Sachii Dosti

Network technology paper
Network technology paperNetwork technology paper
Network technology paperSachii Dosti
 
Subneting and vlsm ntpg
Subneting and vlsm ntpgSubneting and vlsm ntpg
Subneting and vlsm ntpgSachii Dosti
 
Subneting and vlsm ntpg (1)
Subneting and vlsm ntpg (1)Subneting and vlsm ntpg (1)
Subneting and vlsm ntpg (1)Sachii Dosti
 
OSI Physical Layer
OSI Physical LayerOSI Physical Layer
OSI Physical LayerSachii Dosti
 
Addressing the Network – IPv4
Addressing the Network – IPv4Addressing the Network – IPv4
Addressing the Network – IPv4Sachii Dosti
 
OSI Transport Layer
OSI Transport LayerOSI Transport Layer
OSI Transport LayerSachii Dosti
 
Application Layer Functionality and Protocols
Application Layer Functionality and ProtocolsApplication Layer Functionality and Protocols
Application Layer Functionality and ProtocolsSachii Dosti
 
Network Fundamentals – Chapter 2
Network Fundamentals – Chapter 2Network Fundamentals – Chapter 2
Network Fundamentals – Chapter 2Sachii Dosti
 
Network Fundamentals – Chapter 1
Network Fundamentals – Chapter 1Network Fundamentals – Chapter 1
Network Fundamentals – Chapter 1Sachii Dosti
 

More from Sachii Dosti (12)

Network technology paper
Network technology paperNetwork technology paper
Network technology paper
 
Subneting and vlsm ntpg
Subneting and vlsm ntpgSubneting and vlsm ntpg
Subneting and vlsm ntpg
 
Subneting and vlsm ntpg (1)
Subneting and vlsm ntpg (1)Subneting and vlsm ntpg (1)
Subneting and vlsm ntpg (1)
 
Static Routing
Static RoutingStatic Routing
Static Routing
 
OSI Physical Layer
OSI Physical LayerOSI Physical Layer
OSI Physical Layer
 
Data Link Layer
Data Link LayerData Link Layer
Data Link Layer
 
Addressing the Network – IPv4
Addressing the Network – IPv4Addressing the Network – IPv4
Addressing the Network – IPv4
 
OSI Network Layer
OSI Network LayerOSI Network Layer
OSI Network Layer
 
OSI Transport Layer
OSI Transport LayerOSI Transport Layer
OSI Transport Layer
 
Application Layer Functionality and Protocols
Application Layer Functionality and ProtocolsApplication Layer Functionality and Protocols
Application Layer Functionality and Protocols
 
Network Fundamentals – Chapter 2
Network Fundamentals – Chapter 2Network Fundamentals – Chapter 2
Network Fundamentals – Chapter 2
 
Network Fundamentals – Chapter 1
Network Fundamentals – Chapter 1Network Fundamentals – Chapter 1
Network Fundamentals – Chapter 1
 

Recently uploaded

Prescribed medication order and communication skills.pptx
Prescribed medication order and communication skills.pptxPrescribed medication order and communication skills.pptx
Prescribed medication order and communication skills.pptxraviapr7
 
How to Manage Cross-Selling in Odoo 17 Sales
How to Manage Cross-Selling in Odoo 17 SalesHow to Manage Cross-Selling in Odoo 17 Sales
How to Manage Cross-Selling in Odoo 17 SalesCeline George
 
How to Add Existing Field in One2Many Tree View in Odoo 17
How to Add Existing Field in One2Many Tree View in Odoo 17How to Add Existing Field in One2Many Tree View in Odoo 17
How to Add Existing Field in One2Many Tree View in Odoo 17Celine George
 
CapTechU Doctoral Presentation -March 2024 slides.pptx
CapTechU Doctoral Presentation -March 2024 slides.pptxCapTechU Doctoral Presentation -March 2024 slides.pptx
CapTechU Doctoral Presentation -March 2024 slides.pptxCapitolTechU
 
In - Vivo and In - Vitro Correlation.pptx
In - Vivo and In - Vitro Correlation.pptxIn - Vivo and In - Vitro Correlation.pptx
In - Vivo and In - Vitro Correlation.pptxAditiChauhan701637
 
UKCGE Parental Leave Discussion March 2024
UKCGE Parental Leave Discussion March 2024UKCGE Parental Leave Discussion March 2024
UKCGE Parental Leave Discussion March 2024UKCGE
 
How to Use api.constrains ( ) in Odoo 17
How to Use api.constrains ( ) in Odoo 17How to Use api.constrains ( ) in Odoo 17
How to Use api.constrains ( ) in Odoo 17Celine George
 
The basics of sentences session 10pptx.pptx
The basics of sentences session 10pptx.pptxThe basics of sentences session 10pptx.pptx
The basics of sentences session 10pptx.pptxheathfieldcps1
 
Drug Information Services- DIC and Sources.
Drug Information Services- DIC and Sources.Drug Information Services- DIC and Sources.
Drug Information Services- DIC and Sources.raviapr7
 
Maximizing Impact_ Nonprofit Website Planning, Budgeting, and Design.pdf
Maximizing Impact_ Nonprofit Website Planning, Budgeting, and Design.pdfMaximizing Impact_ Nonprofit Website Planning, Budgeting, and Design.pdf
Maximizing Impact_ Nonprofit Website Planning, Budgeting, and Design.pdfTechSoup
 
Easter in the USA presentation by Chloe.
Easter in the USA presentation by Chloe.Easter in the USA presentation by Chloe.
Easter in the USA presentation by Chloe.EnglishCEIPdeSigeiro
 
How to Add a New Field in Existing Kanban View in Odoo 17
How to Add a New Field in Existing Kanban View in Odoo 17How to Add a New Field in Existing Kanban View in Odoo 17
How to Add a New Field in Existing Kanban View in Odoo 17Celine George
 
5 charts on South Africa as a source country for international student recrui...
5 charts on South Africa as a source country for international student recrui...5 charts on South Africa as a source country for international student recrui...
5 charts on South Africa as a source country for international student recrui...CaraSkikne1
 
Human-AI Co-Creation of Worked Examples for Programming Classes
Human-AI Co-Creation of Worked Examples for Programming ClassesHuman-AI Co-Creation of Worked Examples for Programming Classes
Human-AI Co-Creation of Worked Examples for Programming ClassesMohammad Hassany
 
AUDIENCE THEORY -- FANDOM -- JENKINS.pptx
AUDIENCE THEORY -- FANDOM -- JENKINS.pptxAUDIENCE THEORY -- FANDOM -- JENKINS.pptx
AUDIENCE THEORY -- FANDOM -- JENKINS.pptxiammrhaywood
 
How to Make a Field read-only in Odoo 17
How to Make a Field read-only in Odoo 17How to Make a Field read-only in Odoo 17
How to Make a Field read-only in Odoo 17Celine George
 
P4C x ELT = P4ELT: Its Theoretical Background (Kanazawa, 2024 March).pdf
P4C x ELT = P4ELT: Its Theoretical Background (Kanazawa, 2024 March).pdfP4C x ELT = P4ELT: Its Theoretical Background (Kanazawa, 2024 March).pdf
P4C x ELT = P4ELT: Its Theoretical Background (Kanazawa, 2024 March).pdfYu Kanazawa / Osaka University
 
CHUYÊN ĐỀ DẠY THÊM TIẾNG ANH LỚP 11 - GLOBAL SUCCESS - NĂM HỌC 2023-2024 - HK...
CHUYÊN ĐỀ DẠY THÊM TIẾNG ANH LỚP 11 - GLOBAL SUCCESS - NĂM HỌC 2023-2024 - HK...CHUYÊN ĐỀ DẠY THÊM TIẾNG ANH LỚP 11 - GLOBAL SUCCESS - NĂM HỌC 2023-2024 - HK...
CHUYÊN ĐỀ DẠY THÊM TIẾNG ANH LỚP 11 - GLOBAL SUCCESS - NĂM HỌC 2023-2024 - HK...Nguyen Thanh Tu Collection
 
HED Office Sohayok Exam Question Solution 2023.pdf
HED Office Sohayok Exam Question Solution 2023.pdfHED Office Sohayok Exam Question Solution 2023.pdf
HED Office Sohayok Exam Question Solution 2023.pdfMohonDas
 
Practical Research 1 Lesson 9 Scope and delimitation.pptx
Practical Research 1 Lesson 9 Scope and delimitation.pptxPractical Research 1 Lesson 9 Scope and delimitation.pptx
Practical Research 1 Lesson 9 Scope and delimitation.pptxKatherine Villaluna
 

Recently uploaded (20)

Prescribed medication order and communication skills.pptx
Prescribed medication order and communication skills.pptxPrescribed medication order and communication skills.pptx
Prescribed medication order and communication skills.pptx
 
How to Manage Cross-Selling in Odoo 17 Sales
How to Manage Cross-Selling in Odoo 17 SalesHow to Manage Cross-Selling in Odoo 17 Sales
How to Manage Cross-Selling in Odoo 17 Sales
 
How to Add Existing Field in One2Many Tree View in Odoo 17
How to Add Existing Field in One2Many Tree View in Odoo 17How to Add Existing Field in One2Many Tree View in Odoo 17
How to Add Existing Field in One2Many Tree View in Odoo 17
 
CapTechU Doctoral Presentation -March 2024 slides.pptx
CapTechU Doctoral Presentation -March 2024 slides.pptxCapTechU Doctoral Presentation -March 2024 slides.pptx
CapTechU Doctoral Presentation -March 2024 slides.pptx
 
In - Vivo and In - Vitro Correlation.pptx
In - Vivo and In - Vitro Correlation.pptxIn - Vivo and In - Vitro Correlation.pptx
In - Vivo and In - Vitro Correlation.pptx
 
UKCGE Parental Leave Discussion March 2024
UKCGE Parental Leave Discussion March 2024UKCGE Parental Leave Discussion March 2024
UKCGE Parental Leave Discussion March 2024
 
How to Use api.constrains ( ) in Odoo 17
How to Use api.constrains ( ) in Odoo 17How to Use api.constrains ( ) in Odoo 17
How to Use api.constrains ( ) in Odoo 17
 
The basics of sentences session 10pptx.pptx
The basics of sentences session 10pptx.pptxThe basics of sentences session 10pptx.pptx
The basics of sentences session 10pptx.pptx
 
Drug Information Services- DIC and Sources.
Drug Information Services- DIC and Sources.Drug Information Services- DIC and Sources.
Drug Information Services- DIC and Sources.
 
Maximizing Impact_ Nonprofit Website Planning, Budgeting, and Design.pdf
Maximizing Impact_ Nonprofit Website Planning, Budgeting, and Design.pdfMaximizing Impact_ Nonprofit Website Planning, Budgeting, and Design.pdf
Maximizing Impact_ Nonprofit Website Planning, Budgeting, and Design.pdf
 
Easter in the USA presentation by Chloe.
Easter in the USA presentation by Chloe.Easter in the USA presentation by Chloe.
Easter in the USA presentation by Chloe.
 
How to Add a New Field in Existing Kanban View in Odoo 17
How to Add a New Field in Existing Kanban View in Odoo 17How to Add a New Field in Existing Kanban View in Odoo 17
How to Add a New Field in Existing Kanban View in Odoo 17
 
5 charts on South Africa as a source country for international student recrui...
5 charts on South Africa as a source country for international student recrui...5 charts on South Africa as a source country for international student recrui...
5 charts on South Africa as a source country for international student recrui...
 
Human-AI Co-Creation of Worked Examples for Programming Classes
Human-AI Co-Creation of Worked Examples for Programming ClassesHuman-AI Co-Creation of Worked Examples for Programming Classes
Human-AI Co-Creation of Worked Examples for Programming Classes
 
AUDIENCE THEORY -- FANDOM -- JENKINS.pptx
AUDIENCE THEORY -- FANDOM -- JENKINS.pptxAUDIENCE THEORY -- FANDOM -- JENKINS.pptx
AUDIENCE THEORY -- FANDOM -- JENKINS.pptx
 
How to Make a Field read-only in Odoo 17
How to Make a Field read-only in Odoo 17How to Make a Field read-only in Odoo 17
How to Make a Field read-only in Odoo 17
 
P4C x ELT = P4ELT: Its Theoretical Background (Kanazawa, 2024 March).pdf
P4C x ELT = P4ELT: Its Theoretical Background (Kanazawa, 2024 March).pdfP4C x ELT = P4ELT: Its Theoretical Background (Kanazawa, 2024 March).pdf
P4C x ELT = P4ELT: Its Theoretical Background (Kanazawa, 2024 March).pdf
 
CHUYÊN ĐỀ DẠY THÊM TIẾNG ANH LỚP 11 - GLOBAL SUCCESS - NĂM HỌC 2023-2024 - HK...
CHUYÊN ĐỀ DẠY THÊM TIẾNG ANH LỚP 11 - GLOBAL SUCCESS - NĂM HỌC 2023-2024 - HK...CHUYÊN ĐỀ DẠY THÊM TIẾNG ANH LỚP 11 - GLOBAL SUCCESS - NĂM HỌC 2023-2024 - HK...
CHUYÊN ĐỀ DẠY THÊM TIẾNG ANH LỚP 11 - GLOBAL SUCCESS - NĂM HỌC 2023-2024 - HK...
 
HED Office Sohayok Exam Question Solution 2023.pdf
HED Office Sohayok Exam Question Solution 2023.pdfHED Office Sohayok Exam Question Solution 2023.pdf
HED Office Sohayok Exam Question Solution 2023.pdf
 
Practical Research 1 Lesson 9 Scope and delimitation.pptx
Practical Research 1 Lesson 9 Scope and delimitation.pptxPractical Research 1 Lesson 9 Scope and delimitation.pptx
Practical Research 1 Lesson 9 Scope and delimitation.pptx
 

Exploration routing chapter 10 & 11

  • 1. Link-State Routing Protocols - OSPF Routing Protocols and Concepts – Chapter 10 & 11 ITE I Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 1
  • 2. Objectives  Describe the basic features & concepts of link-state routing protocols.  List the benefits and requirements of link-state routing protocols.  Describe the background and basic features of OSPF  Identify and apply the basic OSPF configuration commands  Describe, modify and calculate the metric used by OSPF  Describe the Designated Router/Backup Designated Router (DR/BDR) election process ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 2
  • 3. Link-State Routing  Link state routing protocols -Also known as shortest path first algorithms -These protocols built around Dijkstra’s SPF ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 3
  • 4. Link-State Routing Dikjstra’s algorithm also known as the shortest path first (SPF) algorithm ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 4
  • 5. 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 ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 5
  • 6. Link-State Routing Constructing a link state data base  Routers use a database to construct a topology map of the network ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 6
  • 7. Link-State Routing Shortest Path First (SPF) Tree  Building a portion of the SPF tree Process begins by examining R2’s LSP information -R1 ignores 1st LSP Reason: R1 already knows it’s connected to R2 ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 7
  • 8. Link-State Routing  Determining the shortest path The shortest path to a destination determined by adding the costs & finding the lowest cost ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 8
  • 9. Link-State Routing  Once the SPF algorithm has determined the shortest path routes, these routes are placed in the routing table. ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 9
  • 10. Link-State Routing Protocols Advantages of a Link-State Routing Protocol Routing protocol Builds Topological map Router can independently determine the shortest path to every network. Distance vector No Link State Yes ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Convergence A periodic/ event driven routing updates Use of LSP No Slow Generally No No Yes Fast Generally Yes Yes Cisco Public 10
  • 11. Link-State Routing Protocols Requirements for using a link state routing protocol  Memory requirements Typically link state routing protocols use more memory  Processing Requirements More CPU processing is required of link state routing protocols  Bandwidth Requirements Initial startup of link state routing protocols can consume lots of bandwidth ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 11
  • 12. Introduction to OSPF OSPF Message Encapsulation  OSPF packet type There exist 5 types  OSPF packet header Contains - Router ID and area ID and Type code for OSPF packet type  IP packet header Contains - Source IP address, Destination IP address, & Protocol field set to 89 ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 12
  • 13. Introduction to OSPF OSPF Message Encapsulation  Data link frame header Contains - Source MAC address and Destination MAC address ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 13
  • 14. Introduction to OSPF OSPF Packet Types OSPF PACKET TYPE DESCRIPTION 1: HELLO Discovers neighbors & builds ADJACENCY W/ NEIGHBORS 2: DATABASE DESCRIPTION Checks for database synchronization between routers 3: LINK STATE REQUEST REQUESTS SPECIFIC LINK STATE DATABASE information from router to router 4: LINK STATE UPDATE TRANSPORTS LINK STATE records 5: LINK STATE ACKNOWLEDGEMENT ACKNOWLEDGES RECEIPT OF other packet types ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 14
  • 15. Introduction to OSPF Hello Protocol  OSPF Hello Packet –Purpose of Hello Packet  discover OSPF neighbors & establish adjacencies  advertise guidelines on which routers must agree to become neighbors  used by multi-access networks to elect a designated router and a backup designated router ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 15
  • 16. Introduction to OSPF  Hello Packets continued Contents of a Hello Packet router ID of transmitting router  OSPF Hello Intervals –Usually multicast (224.0.0.5) –Sent every 30 seconds for NBMA segments  OSPF Dead Intervals –This is the time that must transpire before the neighbor is considered down –Default time is 4 times the hello interval ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 16
  • 17. Introduction to OSPF  Hello protocol packets contain information that is used in electing -Designated Router (DR)  DR is responsible for updating all other OSPF routers -Backup Designated Router (BDR)  This router takes over DR’s responsibilities if DR fails ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 17
  • 18. Introduction to OSPF OSPF Link-state Updates  Purpose of a Link State Update (LSU) Used to deliver link state advertisements  Purpose of a Link State Advertisement (LSA) Contains information about neighbors & path costs ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 18
  • 19. Introduction to OSPF OSPF Algorithm  OSPF routers build & maintain link-state database containing LSA received from other routers –Information found in database is utilized upon execution of Dijkstra SPF algorithm –SPF algorithm used to create SPF tree –SPF tree used to populate routing table ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 19
  • 20. Introduction to OSPF  OSPF Authentication –Purpose is to encrypt & authenticate routing information –This is an interface specific configuration –Routers will only accept routing information from other routers that have been configured with the same password or authentication information ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 20
  • 21. Basic OSPF Configuration  OSPF network command -Requires entering: network address wildcard mask - the inverse of the subnet mask area-id - area-id refers to the OSPF area. OSPF area is a group of routers that share link state information -Example: Router(config-router)#network network-address wildcard-ask area area-id ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 21
  • 22. Basic OSPF Configuration  Router ID –This is an IP address used to identify a router –3 criteria for deriving the router ID Use IP address configured with OSPF router-id command -Takes precedence over loopback and physical interface addresses If router-id command not used then router chooses highest IP address of any loopback interfaces If no loopback interfaces are configured then the highest IP address on any active interface is used ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 22
  • 23. Basic OSPF Configuration OSPF Router ID  Router ID & Loopback addresses -Highest loopback address will be used as router ID if router-id command isn’t used -Advantage of using loopback address the loopback interface cannot fail  OSPF stability  The OSPF router-id command –Introduced in IOS 12.0 –Command syntax Router(config)#router ospf process-id Router(config-router)#router-id ip-address  Modifying the Router ID –Use the command Router#clear ip ospf process ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 23
  • 24. Basic OSPF Configuration Verifying OSPF  Use the show ip ospf command to verify & trouble shoot OSPF networks Command will display the following:  Neighbor adjacency -No adjacency indicated by Neighboring router’s Router ID is not displayed A state of full is not displayed -Consequence of no adjacencyNo link state information exchanged Inaccurate SPF trees & routing tables ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 24
  • 25. OSPF Metric  OSPF uses cost as the metric for determining the best route -The best route will have the lowest cost -Cost is based on bandwidth of an interface Cost is calculated using the formula 108 / bandwidth -Reference bandwidth defaults to 100Mbps can be modified using auto-cost reference-bandwidth command ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 25
  • 26. OSPF Metric  COST of an OSPF route Is the accumulated value from one router to the next ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 26
  • 27. OSPF Metric  Usually the actual speed of a link is different than the default bandwidth –This makes it imperative that the bandwidth value reflects link’s actual speed Reason: so routing table has best path information  The show interface command will display interface’s bandwidth -Most serial link default to 1.544Mbps ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 27
  • 28. Basic OSPF Configuration Modifying the Cost of a link  Both sides of a serial link should be configured with the same bandwidth –Commands used to modify bandwidth value Bandwidth command –Example: Router(config-if)#bandwidth bandwidth-kbps ip ospf cost command – allows you to directly specify interface cost -Example:R1(config)#interface serial 0/0/0 R1(config-if)#ip ospf cost 1562 ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 28
  • 29. Basic OSPF Configuration Modifying the Cost of the link  Difference between bandwidth command & the ip ospf cost command –Ip ospf cost command Sets cost to a specific value –Bandwidth command Link cost is calculated ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 29
  • 30. OSPF and Multi-access Networks Challenges in Multi-access Networks  OSPF defines five network types: –Point-to-point –Broadcast Multiaccess –Nonbroadcast Multiaccess (NBMA) –Point-to-multipoint –Virtual links ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 30
  • 31. OSPF in Multi-access Networks  2 challenges presented by multi-access networks –Multiple adjacencies –Extensive LSA flooding ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 31
  • 32. OSPF in Multi-access Networks  Extensive flooding of LSAs For every LSA sent out there must be an acknowledgement of receipt sent back to transmitting router. consequence: lots of bandwidth consumed and chaotic traffic ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 32
  • 33. OSPF in Multi-access Networks  Solution to LSA flooding issue is the use of –Designated router (DR) –Backup designated router (BDR)  DR & BDR selection –Routers are elected to send & receive LSA  Sending & Receiving LSA –DRothers send LSAs via multicast 224.0.0.6 to DR & BDR –DR forward LSA via multicast address 224.0.0.5 to all other routers ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 33
  • 34. OSPF in Multi-access Networks DR/BDR Election Process  DR/BDR elections DO NOT occur in point to point networks ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 34
  • 35. OSPF in Multi-access Networks  DR/BDR elections will take place on multi-access networks as shown below ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 35
  • 36. OSPF in Multi-access Networks  Criteria for getting elected DR/BDR 1. DR: Router with the highest OSPF interface priority. 2. BDR: Router with the second highest OSPF interface priority. 3. If OSPF interface priorities are equal, the highest router ID is used to break the tie. ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 36
  • 37. OSPF in Multi-access Networks  Timing of DR/BDR Election –Occurs as soon as 1st router has its interface enabled on multiaccess network When a DR is elected it remains as the DR until one of the following occurs -The DR fails. -The OSPF process on the DR fails. -The multiaccess interface on the DR fails. ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 37
  • 38. OSPF in Multi-access Networks  Manipulating the election process -If you want to influence the election of DR & BDR then do one of the following Boot up the DR first, followed by the BDR, and then boot all other routers, OR Shut down the interface on all routers, followed by a no shutdown on the DR, then the BDR, and then all other routers. ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 38
  • 39. OSPF in Multi-access Networks OSPF Interface Priority  Manipulating the DR/BDR election process continued –Use the ip ospf priority interface command. –Example:Router(config-if)#ip ospf priority {0 - 255} Priority number range 0 to 255 –0 means the router cannot become the DR or BDR –1 is the default priority value ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 39
  • 40. More OSPF Configuration Redistributing an OSPF Default Route  Topology includes a link to ISP –Router connected to ISP Called an autonomous system border router Used to propagate a default route –Example of static default route R1(config)#ip route 0.0.0.0 0.0.0.0 loopback 1 –Requires the use of the default-information originate command –Example of default-information originate command R1(config-router)#default-information originate ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 40
  • 41. More OSPF Configuration Fine-Tuning OSPF  Modifying OSPF timers –Reason to modify timers Faster detection of network failures –Manually modifying Hello & Dead intervals Router(config-if)#ip ospf hello-interval seconds Router(config-if)#ip ospf dead-interval seconds –Point to be made Hello & Dead intervals must be the same between neighbors ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 41
  • 42. Summary  Link State Routing protocols are also known as Shortest Path First protocols  Summarizing the link state process -Routers 1ST learn of directly connected networks -Routers then say “hello” to neighbors -Routers then build link state packets -Routers then flood LSPs to all neighbors -Routers use LSP database to build a network topology map & calculate the best path to each destination ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 42
  • 43. Summary  Link An interface on the router  Link State Information about an interface such as -IP address -Subnet mask -Type of network -Cost associated with link -Neighboring routers on the link  Link State Packets -After initial flooding, additional LSP are sent out -when a change in topology occurs  Examples of link state routing protocols -Open shortest path first -IS-IS ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 43
  • 44. Summary  RFC 2328 describes OSPF link state concepts and operations  OSPF Characteristics –A commonly deployed link state routing protocol –Employs DRs & BDRs on multi-access networks DRs & BDRs are elected DR & BDRs are used to transmit and receive LSAs –Uses 5 packet types: 1: HELLO 2: DATABASE DESCRIPTION 3: LINK STATE REQUEST 4: LINK STATE UPDATE 5: LINK STATE ACKNOWLEDGEMENT ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 44
  • 45. Summary  OSPF Characteristics –Metric = cost Lowest cost = best path  Configuration –Enable OSPF on a router using the following command R1(config)#router ospf process-id –use the network command to define which interfaces will participate in a given OSPF process Router(config-router)#network network-address wildcard-mask area area-id ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 45

Editor's Notes

  1. Once LSP are created they are forwarded out to neighbors. -After receiving the LSP the neighbor continues to forward it throughout routing area.
  2. Building a portion of the SPF tree -R1 uses 2nd LSP Reason: R1 can create a link from R2 to R5. This information is added to R1’s SPF tree R1 uses 3rd LSP Reason: R1 learns that R2 is connected to 10.5.0.0/16. This link is added to R1’s SPF tree.