networktestinggenius.tk

1) Router1 ——- Router2

On Router1, we have process id of 100.  On Router2: we have process id of 200. Will Router1 & Router2 form neighbourship?

Yes

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2) What is a Sham link?

OSPF can be used to propagate links between a Customer Edge device (CE) and a Provider Edge device (PE). Normal operation of this type of network assumes that the only connections between CEs pass through the provider network. However, when other links or routes between the CEs exist within the same area, problems can arise due to the OSPF preference for Intra-area links over Inter-area links.

3) What are the types of LSA's

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• LSA Type 1: OSPF Router LSA

• LSA Type 2: OSPF Network LSA

• LSA Type 3: OSPF Summary LSA

• LSA Type 4: OSPF ASBR Summary LSA

• LSA Type 5: OSPF ASBR External LSA

• LSA Type 6: OSPF Group Membership LSA

• LSA Type 7: OSPF Not So Stubby Area (NSSA) External LSA

• LSA Type 8: OSPF External Attributes LSA (OSPFv2) / Link Local LSA (OSPFv3)

• LSA Type 9: OSPF Link Scope Opaque (OSPFv2) / Intra Area Prefix LSA (OSPFv3)

• LSA Type 10: OSPF Area Scope Opaque LSA

• LSA Type 11:OSPF AS (Autonomous System) Scope Opaque LSA

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4) Which area tyes accept which wich LSAs. Explain

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5)Give Examples for neibourship and adjecency. 

Neigbour: Two Dr other routers
Adj: DR and BDR

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6) What all the testcases you manually test and verify for a fresh router which is configured with OSPF.

1. Configure OSPF

2. neighborship 

3. Verify LSA

4. Verify routing table

5. Configure and verify OSPF Router ids

6. show ip ospf neighbour

 

7) What is the diffrence OSPF Virtual-links vs GRE tunnels

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Virtual-link:

It is considered part of (Area 0) by default, without any additional configuration.
It dose not require any kind of addressing.
Configuration is only needed under the OSPF routing process.
Only routing updates are tunneled into the virtual-link, but data traffic is not.
Transit area can not be a stub area.

GRE tunnel:

Tunnel interfaces must be created and addressing is required. (can be unnumbered).
Tunnel Address must be advertised into (Area 0) using a network command.
Both routing updates and data traffic are tunneled; this introduces more overhead.
Transit area can be any type; this means its your only option if the transit is a stub area.

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8) What all the thing you verify under show ip ospf neighbour

 

1. Neighbor ID

2. Priority

3. State

4. Dead Time

5. Address

6. Interface

 

9) How to verify that OSPF is running on a particular interface and that the interface is in the desired area?

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From the CLI, enter the show ospf interface command.

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10) What is the difference between the area range command and the summary-address command.

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The area range command is used to summarize networks between areas and is configured on the ABR. The summary-address command is used to summarize networks between autonomous systems and is configured on the ASBR.

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11) If a router configured for OSPF routing is not seeing an OSPF neighbor on an attached network. What will you do?

- Make sure that both routers are configured with the same IP mask, MTU, Interface Hello timer, OSPF Hello interval, and OSPF dead interval.

- Make sure that both neighbors are part of the same area and area type.

- Use the debug and show commands to trace the problem.

 

12)  If same route recieved through different LSA's. what will be the order of preference

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Preference Rule:

Intra Area> Inter Area> External E1 > External E2

or,

LSA-1 or LSA-2 > LSA-3 > LSA-5 or LSA-7

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13)  Refer the topo

Identify the routers and LSAs

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• Routers A, B, E, and F are Internal Routers.  (LSA 1)

• Routers C and D are ABRs. (LSA 3 and LSA 4)

• Router G is an ASBR. (LSA 5)

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13) In diffrent type of area types what are the LSA's accepted?

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14) What are the different LSAs

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