thanks eric for your reply.
is it ok if we talk about the virtual link because i`m not expert in this part.
this is my lab.
the first thing i need to talk about with you is the final design for the virual link .
in my lab what i`m thinking about how the virtual link is going to work is like this
on R2 i have 2.2.2.2/32 on area 0 . R2 is going to put 2.2.2.2/32 into the LSDB on area 1 as a type-3 LSA .
which means R2 is going to send 2.2.2.2/32 to R3 two times:
the first time , R2 is going to send 2.2.2.2/32 to R3 as the normal behavior . send it to R3 as a type-3 LSA to R3 with cost of 1 .
the second time by using the virtual link, R2 is has 2.2.2.2/32 with cost=1 and will send it to R3 with cost of 1 via the virtual link
R3#show ip ospf database summary
LS age: 1581
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 2.2.2.2 (summary Network Number)
Advertising Router: 0.0.0.3
LS Seq Number: 80000001
Checksum: 0x2F01
Length: 28
Network Mask: /32
MTID: 0 Metric: 2
Q.1 but why R3 has cost=2 NOT 1?
LS age: 1639
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 2.2.2.2 (summary Network Number)
Advertising Router: 0.0.0.2
LS Seq Number: 80000001
Checksum: 0x2B07
Length: 28
Network Mask: /32
MTID: 0 Metric: 1
Q.2 why the cost here is 1 ?
Q3 how to change the cost of the virtual link ?
Q4 how to change the area of the virtual link ? the default area is area 0
Q5 does my imagination and what i draw in the paint is correct or not ?
Q6 why i have some LSAs have this flag ( DNA) and other LSAs don`t? for ex.
R3#show ip ospf database summary
OSPF Router with ID (0.0.0.3) (Process ID 1)
Summary Net Link States (Area 0)
Routing Bit Set on this LSA in topology Base with MTID 0
LS age: 6 (DoNotAge)
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 5.5.5.5 (summary Network Number)
Advertising Router: 0.0.0.5
LS Seq Number: 80000001
Checksum: 0x8E94
Length: 28
Network Mask: /32
MTID: 0 Metric: 1
here i have DNA on R3 with the LSA 5.5.5.5/32
LS age: 1556
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 5.5.5.5 (summary Network Number)
Advertising Router: 0.0.0.3
LS Seq Number: 80000001
Checksum: 0xAE74
Length: 28
Network Mask: /32
MTID: 0 Metric: 3
but this does not have (DNA) flag even its the same network