To reduce the size of OSPF Area 100, you configure the area with the no-summaries parameter. After committing this configuration change, you notice that an OSPF router in a remote area is no longer receiving Type 5 LSAs from an ASBR in Area 100.
Which statement is true in this scenario?
A. The ASBR in Area 100 generates Type 5 LSAs, andplaces them in its own database.
B. The ASBR in Area 100 generates Type 5 LSAs, andthey are translated to Type 7 LSAs.
C. The ASBR in Area 100 generates Type 5 LSAs, andthey are blocked by the ABR.
D. The ASBR in Area 100 generates Type 5 LSAs, anda virtual link is required for transport to other areas.
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assuming in question it should be:
configure the area with the “stub no-summaries”
Then A should be the correct answer
I am not aware that it is possible to configure another area type than stub or nssa with “no-summary”^^
Correct me if I am wrong, in a stub area an ASBR does not make sense.
However in a not-so-stubby, totally-stubby and stub areas, no type 5 LSAs are allowed, and should not be generated by ASBR within this area types.
So no answer should be correct.
https://www.juniper.net/documentation/en_US/junos/topics/topic-map/ospf-stub-and-not-so-stubby-areas.html
In addition, you might have a situation when exporting Type 7 LSAs into the NSSA is unnecessary. When an AS boundary router is also an ABR with an NSSA attached, Type 7 LSAs are exported into the NSSA by default. If the ABR is attached to multiple NSSAs, a separate Type 7 LSA is exported into each NSSA by default. During route redistribution, this routing device generates both Type 5 LSAs and Type 7 LSAs. You can disable exporting Type 7 LSAs into the NSSA.
B is correct.
No-summaries convert this area in a NSSA.
This question is confusing. Nowhere it mentioned what type of area 100 is. Option B is not the correct answer as LSA type change happens at ABR and even if could, the remote area should receive the external routes. My hit is option A.
Hi it cannot be B because stub do not allow type 5, C the same as for B and D is just stupid.
I tested this situation in my lab on a vMX14.1 and i see that even A is not correct, i injected a static route (pointing to discard) into OSPF and nothing in OSPF database, it seems that type 5 is simply not generated….
ASBR
junos@ltxPE1# run show route protocol static
inet.0: 59 destinations, 61 routes (58 active, 0 holddown, 1 hidden)
+ = Active Route, – = Last Active, * = Both
3.3.3.0/24 *[Static/5] 00:39:03
Discard
junos@ltxPE1# show protocols ospf
export EXPOSPF;
area 0.0.0.1 {
stub no-summaries;
interface ge-0/0/3.0;
}
junos@ltxPE1# run show ospf database external
[edit]
junos@ltxPE1#
junos@ltxPE1# run show ospf route
Topology default Route Table:
Prefix Path Route NH Metric NextHop Nexthop
Type Type Type Interface Address/LSP
10.128.0.3 Intra Area BR IP 1 ge-0/0/3.0 10.100.1.0
10.128.0.3 Intra Area BR LSP 1
0.0.0.0/0 Inter Network IP 6 ge-0/0/3.0 10.100.1.0
0.0.0.0/0 Inter Network LSP 6
10.100.1.0/31 Intra Network IP 1 ge-0/0/3.0
10.100.1.0/31 Intra Network LSP 1
junos@ltxPE1# run show ospf database asbrsummary
[edit]
ABR (to backbone)
[edit]
junos@ltxP3# show protocols ospf
area 0.0.0.0 {
interface ge-0/0/3.0;
}
area 0.0.0.1 {
stub default-metric 5 no-summaries;
interface ge-0/0/1.0;
}
[edit]
junos@ltxP3# run show ospf database external
[edit]
junos@ltxP3# run show ospf database
OSPF database, Area 0.0.0.0
Type ID Adv Rtr Seq Age Opt Cksum Len
Router 10.127.0.2 10.127.0.2 0x80000003 434 0x22 0xbb7c 36
Router *10.128.0.3 10.128.0.3 0x80000006 1645 0x22 0x86aa 36
Network *10.100.2.0 10.128.0.3 0x80000002 2650 0x22 0xc65c 32
Summary *10.100.1.0 10.128.0.3 0x80000004 647 0x22 0xd468 28
OSPF database, Area 0.0.0.1
Type ID Adv Rtr Seq Age Opt Cksum Len
Router 10.127.0.1 10.127.0.1 0x80000004 1025 0x20 0xd16b 36
Router *10.128.0.3 10.128.0.3 0x80000007 1026 0x20 0x8ca7 36
Network *10.100.1.0 10.128.0.3 0x80000004 1026 0x20 0xdd47 32
Summary *0.0.0.0 10.128.0.3 0x80000002 149 0x20 0x6744 28
[edit]
junos@ltxP3# run show ospf database asbrsummary
[edit]
junos@ltxP3#
Where does it say that area 100 is a stub area?
Should be C, “no-summaries” parameter converts the area into totally stubby and only type 1, 2 & 3 LSAs are sent to backbone area.
I think it should be A,
Because the definition of a stub area does not allow the use of external LSA information within the
area, no functional AS boundary routers can exist within a stub area. If any ASBR configuration
exists, the router will generate one or more Type 5 LSAs and place them into its local database.
However, these external LSAs cannot be sent out any interfaces supporting stub operation.
Yes Answer is A.
Passed today with 100% in OSPF section