OSPF Link State Advertisement (LSA)

OSPF uses an LSDB (link state database) and fills this with LSAs (link state advertisement) LSA holds the topology information and LSA is held in the LSDB. Instead of using 1 LSA packet, OSPF has many different varieties of LSAs.

Here is the list:

  

LSA Types	Description
Type 1	Router LSAs
Type 2	Network LSAs
Type 3 or 4	Summary LSAs
Type 5	Autonomous system external LSAs
Type 6	Multicast OSPF LSAs
Type 7	Defined for not-so-stubby areas
Type 8	External attribute LSAs for  Border Gateway Protocol (BGP)
Type 9, 10, and 11	Opaque LSAs

LSA Type 1: Router LSA

Type 1 router LSA is generated by internal routers. You can identify the “O” routes in the routing table, Type 1 LSA floods within its area only; does not cross ABR. In the type 1 LSA, you will find a list with all the directly connected links of this router.

LSA Type 2: Network LSA

The network LSA or Type 2 creates for each multi-access network. LSA Type 2 is advertised by the DR of the transit network and floods within its area only, network LSA does not cross ABR. You can identify “0” routes in the routing table. In Type 2 LSA you will find all the routers that are connected to the multi-access network, the DR, and the prefix and subnet mask.

LSA Type 3: Summary LSA

 The summary LSA is created by the ABR to send updates from one area to another area. You can identify is “OIA” routes in the routing table. Summary LSA is used to flood network information subnet in the Origin area and cost but does not topology data.

LSA Type 4: ASBR summary LSA

Type 4 LSA is used to advertise ASBR to all other areas in the autonomous system. ASBR summary LSA includes the router ID of the ASBR in the link-state ID field.

LSA Type 5: External LSA

Type 5 LSA External LSA also known as autonomous system external LSA, AS external LSA created by ASBR for external routes redistributed into OSPF (LSA 5), external LSAs are advertised and owned by the originating ASBR. External LSAs flood through the entire autonomous system, and advertising router ID (ASBR) is unchanged throughout the system. Type 4 LSA is needed to find the ASBR.

LSA-6 Multicast OSPF LSA

Type 6 LSA are used in multicast routing (MOSPF routing protocol) multicast LSA (Cisco routers do not support)

LSA Type 7: NSSA external

Type 7 LSA is created by ASBR inside an NSSA, instead of a type 5 LSA. Type 7 LSA flooded only within its area of origin and converted to Type 5 LSA on an ABR toward another area.

·         N1- metric increases as it is passed through the network

·         N2- metric doesn’t increase  (default)

LSA Type 8: external attribute LSA

External attribute LSA is created by ASBR during BGP to OSPF redistribution to preserve BGP attributes of the redistribution network.

LSA Type 9, 10, 11

·         Used in OSPF and BGP inter-networking

Here are the lists of all OSPF labs and theories from CCNA to CCIE.

1.Open Shortest Path First (OSPF) 

2.OSPF Neighbor states

3.OSPF Link State Advertisement (LSA)

4.OSPF STUB, Totally stubby, NSSA, Totally NSSA and(configuration)

5.OSPF Virtual Link

6.Route Redistribution configuration

7.Routing Protocol Authentdication (RIP, and OSPF)

8.Configuring GRE Tunnel instead of virtual link

9. OSPF Autonomous system network map configuration

 

 

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OSPF Virtual Link

An Open Shortest Path First (OSPF) autonomous system all areas must be physically connected to the backbone area (Area 0). In some cases, if this is not possible, we can use a virtual link to connect to the backbone (Area 0) through a non-backbone area. We can also use the virtual links to connect two parts of a partitioned backbone (Area 0) through a non-backbone area. The area through which we configure the virtual link, known as a transit area, must have full routing information. Remember the transit area cannot be a stub area.

Virtual link must be configuring both sides with the same area ID and the corresponding virtual link OSPF neighbor router ID. Show IP OSPF neighbors command give you the router ID information.

area-id	Is identifier for the OSPF area assigned to the transit area for the virtual link. OSPF area ID can be from 0 to 4294967295 or an IP address.
router-id	Router ID is associated with the virtual link neighbor. Specify as an IP address. The router ID appears in the show IP OSPF neighbors command.

In short: virtual link are used to connect a discontiguous area to area 0, virtual link is a logical connection built between routers, virtual links are recommended for backup or temporary connections

Before we start  BGP configuration check out some important  of BGP CCIE exam topics.

Here are the lists of all OSPF labs and theories CCNA to CCIE.

1.Open Shortest Path First (OSPF) 

2.OSPF Neighbor states

3.OSPF Link State Advertisement (LSA)

4.OSPF STUB, Totally stubby, NSSA, Totally NSSA and(configuration)

5.OSPF Virtual Link

6.Route Redistribution configuration

7.Routing Protocol Authentdication (RIP, and OSPF)

8.Configuring GRE Tunnel instead of virtual link

9. OSPF Autonomous system network map configuration

configuration virtual link:

Topology:

GOAL:

• Configure interfaces and assigned IP addresses as per the Topology
• advertise the interfaces using multiple areas defined as per the Topology
• configure the manual router id (RID) R1-11.1.1.1, R2-22.1.1.1, and R3-33.1.1.1
• make sure that the loop-back of R1- 11.0.0.0 routes should be seen on all the other routers

R1#show ip interface brief

Interface              IP-Address      OK? Method Status                Protocol

FastEthernet 0/0        10.1.1.1        YES manual up                    up

Serial3/0                   1.1.1.1         YES manual up                    up

Loopback0              11.0.0.1        YES manual up                    up

Loopback1              11.0.1.1        YES manual up                    up

Loopback2              11.0.2.1        YES manual up                    up

Loopback3              11.0.3.1        YES manual up                    up

R2#show ip interface brief

Interface              IP-Address      OK? Method Status                Protocol

FastEthernet0/0        20.1.1.1        YES manual up                    up

Serial3/0                     1.1.1.2         YES manual up                    up

Serial3/1                     2.2.2.1         YES manual up                    up

R3#show ip interface brief

Interface              IP-Address      OK? Method Status                Protocol

FastEthernet0/0        30.1.1.1        YES manual up                    up

Serial3/1                    2.2.2.2         YES manual up                    up

Serial3/2                    3.3.3.1         YES manual up                    up

R4#show ip interface brief

Interface              IP-Address      OK? Method Status                Protocol

FastEthernet0/0        40.1.1.1        YES manual up                    up

Serial3/2                   3.3.3.2         YES manual up                    up

Loopback0              14.0.0.1        YES manual up                    up

Loopback1              14.0.1.1        YES manual up                    up

Loopback2              14.0.2.1        YES manual up                    up

Loopback3              14.0.3.1        YES manual up                    up

R1(config)#router ospf 1

R1(config-router)#router-id 11.1.1.1

R1(config-router)#NETwork 1.0.0.0 0.255.255.255 Area 20

R1(config-router)#NETwork 10.0.0.0 0.255.255.255 Area 20

R1(config-router)#NETwork 11.0.0.0 0.0.0.255 area 10

R2(config)#router ospf 1

R2(config-router)#router-id 22.1.1.1

R2(config-router)#network 1.0.0.0 0.255.255.255 area 20

R2(config-router)#network 2.0.0.0 0.255.255.255 area 20

R2(config-router)#network 20.0.0.0 0.255.255.255 area 20

R3(config)#router ospf 1

R3(config-router)#router-id 33.1.1.1

R3(config-router)#network 2.0.0.0 0.255.255.255 a 20

R3(config-router)#network 3.0.0.0 0.255.255.255 area 0

R3(config-router)#network 30.0.0.0 0.255.255.255 area 20

R4(config)#router ospf 1

R4(config-router)#network 3.0.0.0 0.255.255.255 area 0

R4(config-router)#network 40.0.0.0 0.255.255.255 area 0

R4(config-router)#network 14.0.0.0 0.0.0.255 area  0

R2#show ip route ospf

Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2

       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

       ia - IS-IS inter area, * - candidate default, U - per-user static route

       o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP

       + - replicated route, % - next hop override

Gateway of last resort is not set

O IA  3.0.0.0/8 [110/128] via 2.2.2.2, 00:28:48, Serial3/1

O     10.0.0.0/8 [110/65] via 1.1.1.1, 00:31:39, Serial3/0

      14.0.0.0/32 is subnetted, 1 subnets

O IA     14.0.0.1 [110/129] via 2.2.2.2, 00:26:24, Serial3/1

O     30.0.0.0/8 [110/65] via 2.2.2.2, 00:29:55, Serial3/1

O IA  40.0.0.0/8 [110/129] via 2.2.2.2, 00:26:39, Serial3/1

R3#show ip route ospf

Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2

       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

       ia - IS-IS inter area, * - candidate default, U - per-user static route

       o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP

       + - replicated route, % - next hop override

Gateway of last resort is not set

O     1.0.0.0/8 [110/128] via 2.2.2.1, 00:29:41, Serial3/1

O     10.0.0.0/8 [110/129] via 2.2.2.1, 00:29:41, Serial3/1

      14.0.0.0/32 is subnetted, 1 subnets

O        14.0.0.1 [110/65] via 3.3.3.2, 00:27:06, Serial3/2

O     20.0.0.0/8 [110/65] via 2.2.2.1, 00:29:41, Serial3/1

O     40.0.0.0/8 [110/65] via 3.3.3.2, 00:27:21, Serial3/2

R4#show ip route ospf

Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2

       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

       ia - IS-IS inter area, * - candidate default, U - per-user static route

       o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP

       + - replicated route, % - next hop override

Gateway of last resort is not set

O IA  1.0.0.0/8 [110/192] via 3.3.3.1, 00:28:06, Serial3/2

O IA  2.0.0.0/8 [110/128] via 3.3.3.1, 00:28:06, Serial3/2

O IA  10.0.0.0/8 [110/193] via 3.3.3.1, 00:28:06, Serial3/2

O IA  20.0.0.0/8 [110/129] via 3.3.3.1, 00:28:06, Serial3/2

O IA  30.0.0.0/8 [110/65] via 3.3.3.1, 00:28:06, Serial3/2

No routes from 11.0.0.0 coming in to routing table  of R2, R3, R3, and R4 as it belong to area 10 which in not directly connected to area 0

in order to make sure that the loopback of R1 (11.0.0.0) routes should be seen on all the other routes we need to configure Virtual-link which allows area 10 to area 0 virtually over area 20 virtual area.

R1#show ip protocols

*** IP Routing is NSF aware ***

Routing Protocol is "ospf 1"

  Outgoing update filter list for all interfaces is not set

  Incoming update filter list for all interfaces is not set

  Router ID 11.1.1.1

  Number of areas in this router is 2. 2 normal 0 stub 0 nssa

  Maximum path: 4

  Routing for Networks:

    1.0.0.0 0.255.255.255 area 20

    10.0.0.0 0.255.255.255 area 20

    11.0.0.0 0.0.0.255 area 10

  Routing Information Sources:

    Gateway         Distance      Last Update

    22.1.1.1             110      00:37:30

    33.1.1.1             110      00:32:35

  Distance: (default is 110)

R3#show ip protocols

*** IP Routing is NSF aware ***

Routing Protocol is "ospf 1"

  Outgoing update filter list for all interfaces is not set

  Incoming update filter list for all interfaces is not set

  Router ID 33.1.1.1

  It is an area border router

  Number of areas in this router is 2. 2 normal 0 stub 0 nssa

  Maximum path: 4

  Routing for Networks:

    2.0.0.0 0.255.255.255 area 20

    3.0.0.0 0.255.255.255 area 0

    30.0.0.0 0.255.255.255 area 20

  Routing Information Sources:

    Gateway         Distance      Last Update

    11.1.1.1             110      00:35:57

    14.0.3.1             110      00:33:22

    22.1.1.1             110      00:35:57

  Distance: (default is 110)

R1(config)#router ospf 1

R1(config-router)#area 20 virtual-link 33.1.1.1

R3(config)#router ospf 1

R3(config-router)#area 20 virtual-link 11.1.1.1

R2#show ip route ospf

Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2

       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

       ia - IS-IS inter area, * - candidate default, U - per-user static route

       o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP

       + - replicated route, % - next hop override

Gateway of last resort is not set

O IA  3.0.0.0/8 [110/128] via 2.2.2.2, 00:40:25, Serial3/1

O     10.0.0.0/8 [110/65] via 1.1.1.1, 00:43:16, Serial3/0

      11.0.0.0/32 is subnetted, 1 subnets

O IA     11.0.0.1 [110/65] via 1.1.1.1, 00:02:47, Serial3/0

      14.0.0.0/32 is subnetted, 1 subnets

O IA     14.0.0.1 [110/129] via 2.2.2.2, 00:38:01, Serial3/1

O     30.0.0.0/8 [110/65] via 2.2.2.2, 00:41:32, Serial3/1

O IA  40.0.0.0/8 [110/129] via 2.2.2.2, 00:38:16, Serial3/1

R3#show ip route ospf

Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2

       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

       ia - IS-IS inter area, * - candidate default, U - per-user static route

       o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP

       + - replicated route, % - next hop override

Gateway of last resort is not set

O     1.0.0.0/8 [110/128] via 2.2.2.1, 00:41:43, Serial3/1

O     10.0.0.0/8 [110/129] via 2.2.2.1, 00:41:43, Serial3/1

      11.0.0.0/32 is subnetted, 1 subnets

O IA     11.0.0.1 [110/129] via 2.2.2.1, 00:03:18, Serial3/1

      14.0.0.0/32 is subnetted, 1 subnets

O        14.0.0.1 [110/65] via 3.3.3.2, 00:39:08, Serial3/2

O     20.0.0.0/8 [110/65] via 2.2.2.1, 00:41:43, Serial3/1

O     40.0.0.0/8 [110/65] via 3.3.3.2, 00:39:23, Serial3/2

R4#show ip route ospf

Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2

       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

       ia - IS-IS inter area, * - candidate default, U - per-user static route

       o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP

       + - replicated route, % - next hop override

Gateway of last resort is not set

O IA  1.0.0.0/8 [110/192] via 3.3.3.1, 00:40:10, Serial3/2

O IA  2.0.0.0/8 [110/128] via 3.3.3.1, 00:40:10, Serial3/2

O IA  10.0.0.0/8 [110/193] via 3.3.3.1, 00:40:10, Serial3/2

      11.0.0.0/32 is subnetted, 1 subnets

O IA     11.0.0.1 [110/193] via 3.3.3.1, 00:03:35, Serial3/2

O IA  20.0.0.0/8 [110/129] via 3.3.3.1, 00:40:10, Serial3/2

O IA  30.0.0.0/8 [110/65] via 3.3.3.1, 00:40:10, Serial3/2

R1#show ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface

33.1.1.1          0   FULL/  -           -        2.2.2.2         OSPF_VL0

22.1.1.1          0   FULL/  -        00:00:32    1.1.1.2         Serial3/0

R1#show ip ospf virtual-links

Virtual Link OSPF_VL0 to router 33.1.1.1 is up

  Run as demand circuit

  DoNotAge LSA allowed.

  Transit area 20, via interface Serial3/0

 Topology-MTID    Cost    Disabled     Shutdown      Topology Name

        0           128       no          no            Base

  Transmit Delay is 1 sec, State POINT_TO_POINT,

  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5

    Hello due in 00:00:04

    Adjacency State FULL (Hello suppressed)

    Index 1/2, retransmission queue length 0, number of retransmission 0

    First 0x0(0)/0x0(0) Next 0x0(0)/0x0(0)

    Last retransmission scan length is 0, maximum is 0

    Last retransmission scan time is 0 msec, maximum is 0 msec

R4#ping 11.0.0.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 11.0.0.1, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 80/131/172 ms

 

 

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OSPF Neighbor states

OSPF neighbor states

During the OSPF adjacency formation process, two OSPF routers transition through several states, which include:

Add caption

1. Down-  first OSPF neighbor state in this state no information (hello) has been received from the neighbouring router but in the down state hello packets can be sent to the neighbor.
2. Attempt- this state is only valid for manually configured neighbor in an non broadcast multi-access (NBMA) environment. router send unicast hello packets every interval to the neighbor orm which hello's have not been received within the dead interval.
3. Init-OSPF router recieved a hello packets from its neighbor but the receiving router's ID was not include in the hello packets.

Router ID (RID)- This is the highest active IP address on the router. Router ID is configured manually and dynamically if its not configured by the administrator, router choose the highest IP of the loopback interface is used and if loopback is not configured, Router choose the highest IP of physical interface.   

 Configure Router ID-

R1(config)#router ospf 1
R1(config-router)#router-id ?
  A.B.C.D  OSPF router-id in IP address format


4. 2 WAY- 2 way state is attained when the router receiving the hello packets and router seen its own router ID within the received  hello packet. Bidirectional communication has been established. In the broadcast multi-access networks, an election can occur after this point.

5. Exstart- the actual process of exchanging link states information can start between the OSPF  routers. master/slave relationship is established and initial sequence numbers are exchange.

6.Exchange- In the Exchange state, OSPF routing information is exchanged using Database description (DBD or DD) packets and link-state request (LSR) and link state update (LSU) packets may also be sent. In this state OSPF router see what LSA's they have and what LSA's they do not have.

7.Full- In the full state, all LSA's information is synchronized among neighbors and adjacency has been established. 

%OSPF-5-ADJCHG: Process 1, Nbr 20.1.1.1 on Serial3/0 from LOADING to FULL, Loading Done


R1#show ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface
20.1.1.1          0   FULL/  -        00:00:39    1.1.1.2         Serial3/0

Before we start  BGP configuration check out some important  of BGP CCIE exam topics.

Here are the lists of all OSPF labs and theories CCNA to CCIE.

1.Open Shortest Path First (OSPF) 

2.OSPF Neighbor states

3.OSPF Link State Advertisement (LSA)

4.OSPF STUB, Totally stubby, NSSA, Totally NSSA and(configuration)

5.OSPF Virtual Link

6.Route Redistribution configuration

7.Routing Protocol Authentdication (RIP, and OSPF)

8.Configuring GRE Tunnel instead of virtual link

9. OSPF Autonomous system network map configuration

 

 

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What is Open Shortest Path First (OSPF) complete?

Open Shortest Path First (OSPF) 

Open shortest path first is an open standard routing protocol that’s been implemented by a wide variety of network venders, include Cisco. And it’s that open standard characteristic that’s the key to OSPF flexibility and popularity. OSPF use the Dijkstra algorithm to initially construct a shortest path tree and follows that by populating the routing table with the resulting best route. Its quick convergence is another reason it’s a favorite. Another two great advantages OSPF offers are that it supports multiple, equal-cost routes to the same destination and it also supports both IPv4 and IPv6 routed protocols.

Here’s a list that summarizes some of OSPF features:

·         Link-state routing protocol.

·         Open standard (IETF)

·         Allow for the creation of areas and autonomous system

·         Minimize the routing update traffic

·         It’s highly flexible, versatile, and scalable

·         Support VLSM/CIDR

·         Offers an unlimited hop count

Terminology

Link a link is a network or router interface assigned to any given network. When an interface is added to the OSPF process, it’s considered to be a link.

Router ID the router ID (RID) is an IP address used to identify the router. Cisco routers choose the router ID by using the highest IP address of all configured loopback interface. To router ID is basically the “name” of each router.

Neighbor neighbor are two or more routers that have an interface on a common network, such as two routers connected on a point-to-point serial link. OSPF neighbors must have a numbers of common configuration options to be able to successfully establishing a neighborship, and all of these options must be configured exactly the same way:

·         Area ID

·         Stub area flag

·         Authentication (if using one)

·         Hello and Dead intervals

Adjacency an adjacency is a relationship between two OSPF routers that permits the direct exchange of routes updates. OSPF directly share routes only with neighbors that have also established adjacencies. Not all the routers neighbors will become adjacent – this depends upon both the type of network and configuration of the routers.

Designated router a designated router(DR) is elected when OSPF routers connected to the same broadcast network to minimize the number of adjacencies formed and to publicize received routing information to and from the remaining routers on the broadcast network or link. Election are won based Upon a router’s priority level, with the one having the highest priority becoming the winner. If there’s a tie, the router ID will be used break it.

Backup designated router a backup designated router is hot standby for the DR on broadcast, or multi-access, links. The BDR receives all routing update from OSPF adjacent routers but does not disperse LSA updates.

Hello protocol the hello protocol provide dynamic neighbor discovery and maintain neighbor relationship. Hello packets are sent to multicast address 224.0.0.5.

Neighbor database the neighbor database is a list of all OSPF routers for which hello packets have been seen.

Topological database the topological database contains information from all of the link state advertisement packets that have been received from an area.

Link state advertisement a link state advertisement (LSA) is an OSPF data packet containing link-state and routing information that’s shared among OSPF routers. LAS packets are used to update and maintain the topological database. There are different types of LSA packets.

OSPF area an ospf area is a grouping of contagious networks and routers.

Broadcast (multi-access) broadcast multi-access networks such as Ethernet allow multiple devices to connect to or access the same network, enabling a broadcast ability in which a single packet is delivered to all nodes on the network.

Nonbroadcast multi-access (NBMA) nonbroadcast multi-access network are networks such as frame relay, X.25, and Asynchronous Transfer Mode (ATM). These kinds of networks allow for multi-access without broadcast ability like Ethernet.

Point-To-Point   Point-To-Point   refers to a type of network topology made up of a direct connection between two routers that provides a single communication path.

Point-to-multipoint Point-to-multipoint refers to type of network topology made up of a series of connections between a single interface on one router and multiple destination routers

 OSPF Metric

OSPF uses a metric referred to as cost. A cost is associated with every outgoing interface include in an SPF tree. Ospf metric is not define in standards, every vendor uses different formula to calculate metric. cisco  uses a simple equation of 108/bandwidth.

Before we start  BGP configuration check out some important  of BGP CCIE exam topics.

Here are the lists of all OSPF labs and theories CCNA to CCIE.

1.Open Shortest Path First (OSPF) 

2.OSPF Neighbor states

3.OSPF Link State Advertisement (LSA)

4.OSPF STUB, Totally stubby, NSSA, Totally NSSA and(configuration)

5.OSPF Virtual Link

6.Route Redistribution configuration

7.Routing Protocol Authentdication (RIP, and OSPF)

8.Configuring GRE Tunnel instead of virtual link

9. OSPF Autonomous system network map configuration

Topology 

Goal: verifying reachability between routers LUKE and MARK with basic OSPF  single area,

LUKE#show ip interface brief

Interface              IP-Address             OK? Method         Status             Protocol

Serial3/0              10.1.1.1                  YES manual           up                    up

Loopback0           192.168.100.50      YES manual          up                    up

MARK#show ip interface brief

Interface              IP-Address      OK? Method        Status                Protocol

Serial3/0              10.1.1.2        YES manual              up                    up

Loopback0        192.168.150.75  YES manual           up                    up

LUKE(config)#router ospf 1

LUKE(config-router)#network 10.0.0.0 0.255.255.255 area 0

LUKE(config-router)#network 192.168.100.0 0.0.0.255 area 0

MARK(config)#router ospf 1

MARK(config-router)#network 10.0.0.0 0.255.255.255 area 0

MARK(config-router)#network 192.168.150.0  0.0.0.255 area 0

LUKE#show ip ospf interface brief

Interface    PID   Area            IP Address/Mask    Cost  State Nbrs F/C

Lo0          1     0               192.168.100.50/24  1     LOOP  0/0

Se3/0        1     0               10.1.1.1/8         64    P2P   1/1

MARK#show ip ospf interface br

Interface    PID   Area            IP Address/Mask    Cost  State Nbrs F/C

Se3/0        1     0               10.1.1.2/8         64    P2P   1/1

LUKE#ping 192.168.150.75

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 192.168.150.75, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 4/27/68 ms

LUKE#traceroute 192.168.150.75

Type escape sequence to abort.

Tracing the route to 192.168.150.75

VRF info: (vrf in name/id, vrf out name/id)

  1 10.1.1.2 52 msec 88 msec 24 msec

MARK#ping 192.168.100.50

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 192.168.100.50, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 20/24/36 ms

MARK#traceroute 192.168.150.75

Type escape sequence to abort.

Tracing the route to 192.168.150.75

VRF info: (vrf in name/id, vrf out name/id)

  1 192.168.150.75 8 msec 8 msec 8 msec