— Exhibit —
[edit protocols ospf]
user@R2# show
area 0.0.0.6 {
nssa {
default-lsa default-metric 10;
area-range 184.23.12.0/24;
}
interface ge-1/1/4;
}
[edit protocols ospf]
user@R2# show ospf database
OSPF database, Area 0.0.0.0
Type ID Adv Rtr Seq Age Opt Cksum Len
Router *192.168.0.2 192.168.0.2 0x80000004 749 0x22 0x87c2 60
Router 192.168.0.3 192.168.0.3 0x80000004 399 0x22 0x94b5 60
Summary *10.0.0.0 192.168.0.2 0x80000003 19 0x22 0xe2e4 28
Summary *192.168.0.1 192.168.0.2 0x80000002 1100 0x22 0xbda7 28
OSPF database, Area 0.0.0.6
Type ID Adv Rtr Seq Age Opt Cksum Len
Router 192.168.0.1 192.168.0.1 0x80000004 404 0x20 0x76db 60
Router *192.168.0.2 192.168.0.2 0x80000003 1802 0x20 0x319b 48
Summary *11.0.0.0 192.168.0.2 0x80000002 2504 0x20 0xf5d3 28
Summary *192.168.0.2 192.168.0.2 0x80000003 2153 0x20 0xc5a0 28
Summary *192.168.0.3 192.168.0.2 0x80000002 398 0x20 0xc79d 28
NSSA *0.0.0.0 192.168.0.2 0x80000001 11 0x20 0xcbf1 36
NSSA 184.23.12.0 192.168.0.1 0x80000002 447 0x28 0xb93f 36
OSPF AS SCOPE link state database
Type ID Adv Rtr Seq Age Opt Cksum Len
Extern *184.23.12.0 192.168.0.2 0x80000003 11 0x22 0x28d6 36
— Exhibit —
Click the Exhibit button.
Referring to the exhibit, which two statements are correct? (Choose two.)
A.
R2 injects a Type 3 LSA for 184.23.12.0/24 into the backbone.
B.
R2 is an ABR.
C.
R2 injects a Type 5 LSA for 184.23.12.0/24 into the backbone.
D.
R2 is an ASBR.
Correct answers are B and D.
A and C are not correct, because we don’t see this link in the output under Area 0.0.0.0
0
0
taking back…
B and C are correct answers.
A) R2 will never insert originally LSA7 as LSA3 in to the backbone
B) it is ABR because we see summary routes to be generated
C) area-range config says this ABR reports routes to backbone within the specified subnet
D) we miss any NSSA route inserted from R2
the nssa 0/0 route is coming from ABR in between area 6 and area 0 (see default-lsa config option); this dump is missing the configuration option type-7 in the R2 configuration – that would explain the NSSA type of the LSA
0
0
B and C are correct.
R2 is an ABR since the output shows two databases from different areas (backbone and 6)
Re injects a type 5 LSA for 184.23.12/24 in to the backbone is also true, we can see in the database how R2 learns about 184.23.12/24 trough an LSA type 7 or NSSA, generated by some router with ID 192.168.0.1 (NSSA 184.23.12.0 192.168.0.1). And then it creates its own LSA type 5 or external to eventually inject it in to the backbone. We can see the asterisk beside the route : Extern *184.23.12.0 192.168.0.2 0x80000003 11 0x22 0x28d6 36.
As per the following link:
http://www.juniper.net/documentation/en_US/junos13.2/topics/reference/configuration-statement/area-range-edit-protocols-ospf.html
“For a not-so-stubby area (NSSA), summarize a range of IP addresses when sending NSSA link-state advertisements. The specified prefixes are used to aggregate external routes learned within the area when the routes are advertised to other areas. To specify multiple prefixes, include multiple area-range statements. All external routes learned within the area that do not fall into one of the prefixes are advertised individually to other areas”
From what I understand, it will use type 3 LSA or summary LSA if the router creates the LSA type 7 NSSA, this is why aswer A is not correct.
Feel free to correct me if I am wrong.
-“Meditation is the medicine of the mind”
0
0
B & C
0
0