
OSPF is a famous routing protocol, often used in enterprise or campus. Actually, almost every network engineer is skilled master of OSPF J. Today we just discuss some simple example.
As we know, OSPF use LSA calculate routes. OSPF have LSA-1 – LSA-5 calculate intra or inter regular area routes.
Like ‘O’ use LSA-1 and LSA-2 calculated, ‘O IA’ use LSA-1, LSA-2 and LSA-3 calculated, ‘O E’ use LSA-1, LSA-2, LSA-5 and LSA-3 or LSA-4 calculated.
Question 1:
LSA-5 calculate
when not need LSA-4?
when need LSA-4 help calculate?
when need LSA-3 help calculate?
Question 2:

R1 have an loopback0 1.1.1.1/32, network in area 1
R3 have an loopback0 3.3.3.3/32, network in area 0,
The number on the topology is the link cost
area 1 is a regular area, area 0 is backbone area
R3 will use lo0 access R1 lo0 1.1.1.1, which path will use?
- R3->R2->R1
- R3->R4->R1
- load-balance
- drop
Question 3:

R1 have an loopback0 1.1.1.1/32, network in area 1
R3 have an loopback1 33.33.33.33/32, network in eigrp 100, and redistribute into OSPF
The number on the topology is the link cost
area 1 is a regular area, area 0 is backbone area
R1 will use lo0 access R3 lo1 33.33.33.33, which path will use?
- R1->R2->R3
- R1->R4->R3
- load-balance
- drop
Question 4:

R1 have an loopback0 1.1.1.1/32, network in area 1
R3 have an loopback0 3.3.3.3/32, network in area 0,
The number on the topology is the link cost
area 1 is a stub area, area 0 is backbone area
R2 have command: area 1 stub
R4 have command: area 1 stub no-summary
R1 will use lo0 access R3 lo0 3.3.3.3, which path will use?
- R1->R2->R3
- R1->R4->R3
- load-balance
- drop
Question 5:

R1 have an loopback0 1.1.1.1/32, network in area 1
R3 have an loopback1 33.33.33.33/32, network in eigrp 100, and redistribute into OSPF
The number on the topology is the link cost
area 1 is a stub area, area 0 is backbone area
R2 have command: area 1 stub
R4 have command: area 1 stub no-summary
R1 will use lo0 access R3 lo1 33.33.33.33, which path will use?
- R1->R2->R3
- R1->R4->R3
- load-balance
- drop
OK, just 5 questions, more questions will show you next time, if you interested, type your answer below.
Have fun!!!
By lecturer James
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