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8/12/2019 OSPF v2
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OSPF
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Content
Introduce OSPF
Operation of OSPF
OSPF Network Type OSPF Area Structure
OSPF Multi Area Routing
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Classification of Routing Protocol
Interior Gateway Protocols Exterior Gateway
Protocols
Distance Vector L ink State Path vector
Classful RIP IGRP EGP
Classless RIPv2 EIGRP OSPFv2 IS-IS BGPv4
IPv6 RIPng EIGRP
for IPv6
OSPFv3 IS-IS
forIPv6
BGPv4 for IPv6
Overview
Classification of Routing Protocol
Interior Gateway Protocols Exterior Gateway
Protocols
Distance Vector L ink State Path vector
Classful RIP IGRP EGP
Classless RIPv2 EIGRP OSPFv2 IS-IS BGPv4
IPv6 RIPng EIGRP
for IPv6
OSPFv3 IS-IS
forIPv6
BGPv4 for IPv6
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Router ID
Adjacency
LSATopology Table
SPF AlgorithmSPF
treeRouting table
OSPF Operation
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OSPF Packet
Hello To discover neighbors and form DR/BDR relationship and
exchange neighbor capabilities.
DBD Check for database synchronization between routers
Link-state
request
Requests specific link-state records from another router
Link-state
update
Sends specifically requested link-state records
Link-state
acknowledge
Acknowledges the other packet types
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Neighbors & Adjacencies
Hello
The routers sends & received
hello packets to & from its
neighbor router
After 2 router establishAdjacency, they synchronize
their LSDBs with each other
Ther routers are full adjacency
with each other
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Before two routers can form an OSPF neighbor
adjacency, they must agree on these values:
Hello Interval
Dead Interval
IP MTU must match
Area ID
Stub Area Flag
Authentication Password
Neighbors & Adjacencies
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Down State This state means that no information has been received from neighbor yet
Attemp State Use in NBMA environment. Ther router sends unicast hello packets every poll interval to
the neighbor
I ni t State This state specifies that the router has received a hello packet from its neighbor, but the
receiving router's ID was not included in the hello packet.
2-way State This state designates that bi-directional communication has been established between
two routers. Bi-directional means that each router has seen the other's hello packet.
Exstar t State Once the DR and BDR are elected, the actual process of exchanging link state
information can start between the routers and their DR and BDR.
Exchange State OSPF routers exchange database descriptor (DBD) packets. Database descriptors contain
link-state advertisement (LSA) headers only and describe the contents of the entire link-state database.
Loading State The actual exchange of link state information occurs. Based on the information provided
by the DBDs, routers send link-state request packets. The neighbor then provides the
requested link-state information in link-state update packets
Ful l State All the router and network LSAs are exchanged and the routers' databases are fully
synchronized.
Neighbors State
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Neighbors & Adjacencies
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OSPF uses costas the metric for determining the best
route
Cost=---------------------------
Default Reference Bandwidth = 10
OSPF Metric
Reference Bandwidth
Bandwidth
8
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Interface Type Bandwidth Default cost
9.6 kbps line 9.6 kbps 10,416
56 kbps l ine 56 kbps 1,785
64 kbps l ine 64 kbps 1,562
T1 cir cui t 1.544 Mbps 64E1 cir cuit 2.048 Mbps 48
T3 cir cui t 45 Mbps 2
Ethernet 10 Mbps 10
Fast Ethernet 100 Mbps 1
Gigabit Ethernet 1 Gbps 1
10 Gigabit Ethernet 10 Gbps 1
4 Mbps Token Ring 4 Mbps 25
OSPF Metric
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Shortest Path First Algorithm
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Shortest Path First Algorithm
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Basic OSPF Configuration
192.168.12.0/24 192.168.23.0/24
.1 .2 .2 .3R1 R2 R3
R1(config)#router ospf 1
R1(config-router)#router-id 1.1.1.1
R1(config-router)#network 192.168.12.1 0.0.0.0 area 0
R2(config)#router ospf 1
R2(config-router)#router-id 2.2.2.2
R2(config-router)#network 192.168.12.2 0.0.0.0 area 0
R2(config-router)#network 192.168.23.2 0.0.0.0 area 0
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Point to Point
Broadcast Multi Access
Non Broadcast Multi Access
Point to Multipoint
Point to Multipoint Non Broadcast
OSPF Network Type
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Hello Interval 10 s Dead Interval 40 s
No DR/BDR election
Multicast updates 224.0.0.5
Neighbor automatic
Point to Point
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Hello Interval 30 s
Dead Interval 120 s
DR/BDR election
Updates are sent as unicast
Neighbor manual
Non Broadcast Multi Access
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Cisco proprietary
Host route are added inrouting table
Hello Interval 10 s
Dead Interval 40 s
No DR/BDR election
Multicast updates224.0.0.5
Neighbor automatic
Point to Multipoint
HUB
SPOKE SPOKE
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Cisco proprietary
Host route are added
in routing table
Hello Interval 30 s
Dead Interval 120 s
No DR/BDR election
Unicast Update
Neighbor manual
Point to Multipoint non Broadcast
HUB
SPOKE SPOKE
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Electing DR& BDR
Highest priority
Highest IP Loop back
Interface
Highest IP Physical
Interface
DROther send update
Multicast 224.0.0.6 to DR
& BDR
OSPF & Multi Access Media
DRBDR
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DR send update Multicast
224.0.0.5 to all other
router
OSPF & Multi Access Media
DRBDR
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Configuration OSPF in NBMA
Router(config)#inteface f0/0
Router(config-if)#ip ospf network non-broadcast
Router(config)#router ospf 1
Router(config-router)#neighbor 192.168.0.2
Router(config-router)#neighbor 192.168.0.3
Router(config-router)#neighbor 192.168.0.4
R1
R2
R3
R4
192.168.0.0/24.1
.2
.3
.4
F0/0
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OSPF Area Structure
OSPF Hierarchical
network structure
To reduce SPF
calculations Backbone Area
(Area 0)
None Backbone Area
( Regular Area)
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OSPF Router Type
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OSPF LSA
LSA Type 1
(Router LSA)
Generated by all routers in an area to describe their directly
attached links (Intra-area routes)
LSA Type 2
(Network LSA)
Generated by the DR of a broadcast or Nonbroadcast segment to
describe the neighbors connected to the segment
LSA Type 3(Summary LSA)
Generated by the ABR to describe a route to neighbors outside thearea. (Inter-area routes)
LSA Type 4
(Summary LSA)
Generated by the ABR to describe a route to an ASBR to neighbors
outside the area
LSA Type 5
(External LSA)
Generated by ASBR to describe routes redistributed into the area
LSA Type 6
(Multi cast LSA)
Not support on Cisco Router
LSA Type 7
(NSSA External
LSA)
Generated by an ASBR inside a NSSA to describe routes
redistributed into the NSSA. LSA 7 is translated into LSA 5 as it
leaves the NSSA
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OSPF Standard Area
Type 1/2 Type 1/2
Type 3
Type 5
Type 4
Area 0 Area 10
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OSPF Stub Area
Type 1/2 Type 1/2
Type 3
Area 0 Stub Area 10
Default Route
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OSPF Totally Stuby Area
Type 1/2 Type 1/2
Area 0 Totallly Stuby Area 10
Default Route
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OSPF Not So Stuby Area
Type 1/2 Type 1/2
Type 4
Area 0 Not So Stubby Area 10
Type 7Type 5
Default Route
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OSPF Multi Area RoutingArea 0
Area 1Area 2
Virtual link Or GRE Tunnel
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OSPF Multi Area RoutingArea 0Area 0
Virtual link Or GRE Tunnel
Area 2
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Configuration Virtual Link
Area 0Area 0Area 2
R2 R4
R2
R2(config)#router ospf 1
R2(config-router)#router-id 2.2.2.2
R2(config-router)#area 1 virtual-link 4.4.4.4
R4
R4(config)#router ospf 1
R4(config-router)#router-id 4.4.4.4
R4(config-router)#area 1 virtual-link 2.2.2.2
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Configuration GRE Tunnel
192.168.24.0/24
Area 0Area 0Area 2
R2 R4
R2
R2(config)#interface Tunnel 24
R2(config-if)#ip address 10.0.24.2 255.255.255.0
R2(config-if)#tunnel source FastEthernet 0/1
R2(config-if)#tunnel destination 192.168.24.4
10.0.0.0/24
R4
R4(config)#interface Tunnel 24
R4(config-if)#ip address 10.0.24.4 255.255.255.0
R4(config-if)#tunnel source FastEthernet 0/0
R4(config-if)#tunnel destination 192.168.24.2
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THANK YOU FOR ATTENTION