OSPF NSSA dan Totally NSSA
Halo semua kembali lagi di blog ini, Pada tulisan kali ini kita akan lanjut membahas materi dan lab OSPF. Sebelumnya kita tahu bahwa terdapat area backbone, area standard, dan juga spesial area yaitu Stub dan Totally Stub pada OSPF. Kali ini kita akan membahas materi lanjutan dari area spesial OSPF yaitu NSSA dan Totally NSSA. Jika pada Stub dan Totally Stub external route atau LSA Type-3,4,5 tidak dapat diterima yang dikonversi menjadi default route, Maka jika kita tetap ingin mengadvertise External Route tersebut pada area Stub kita akan menggunakan area spesial ini yaitu NSSA yang akan mengadvertise prefix external route tersebut namun bukan dengan LSA Type-3,4,5 tadi, Melainkan dengan LSA Type-7.
Topologi
Berikut adalah topologi yang akan kita gunakan, Sebelumnya topologi ini sudah kita gunakan pada Routing OSPF Stub dan Totally Stub area namun kita akan menambahkan routing RIP pada R3 yang akan diadvertise kedalam routing OSPF kembali, Routing RIP ini jika di advertise dalam keadaan normal akan membawa LSA Type-5 pada OSPF, Namunnn Area 1 tersebut adalah Stub yang tidak mengizinkan LSA Type tersebut ada. Nahh maka peran NSSA disini yang akan mengubah LSA Type-5 tersebut menjadi Type-7 sehingga routing RIP yang di advertise oleh R3 kedalam OSPF tetap dapat diterima oleh R1 sebagai LSA Type-5. Menarikk banget nih langsung aja kita coba.
NSSA dan Totally NSSA
NSSA (Not So Stubby Area) juga merupakan area spesial pada OSPF selain Stub, NSSA merupakan opsi jika kita tetap ingin mengadvertise external route namun terdapat area yang menolak keberadaan dari LSA Type-5 yaitu Stub. Dengan NSSA LSA Type-5 tersebut dikonversi menjadi LSA Type-7 pada area NSSA yang kemudian pada area dibelakang NSSA ini akan dikonversi kembali menjadi LSA Type-5.
Totally NSSA akan membuat Inter Area juga akan dikonversi menjadi defautl route pada router yang di set kedalam area ini.
Lab Pre-Configuration
R1 ===== R1(config)#int lo0 R1(config-if)#ip add 1.1.1.1 255.255.255.255 R1(config-if)#int lo1 R1(config-if)#ip add 100.100.100.1 255.255.255.255 R1(config-if)#int lo2 R1(config-if)#ip add 100.100.100.2 255.255.255.255 R1(config-if)#int lo3 R1(config-if)#ip add 100.100.100.3 255.255.255.255 R1(config-if)#int lo4 R1(config-if)#ip add 100.100.100.4 255.255.255.255 R1(config-if)#int lo5 R1(config-if)#ip add 100.100.100.5 255.255.255.255 R1(config-if)#int lo6 R1(config-if)#ip add 100.100.100.6 255.255.255.255 R1(config-if)#int lo7 R1(config-if)#ip add 100.100.100.7 255.255.255.255 R1(config)#int gig0/0 R1(config-if)#ip add 12.12.12.1 255.255.255.0 R1(config-if)#no sh 1(config)#router eigrp 10 R1(config-router)#network 100.100.100.4 0.0.0.0 R1(config-router)#network 100.100.100.5 0.0.0.0 R1(config-router)#network 100.100.100.6 0.0.0.0 R1(config-router)#network 100.100.100.7 0.0.0.0 R1(config-router)#no auto-summary R1(config-router)#exit R1(config)#router ospf 1 R1(config-router)#router-id 1.1.1.1 R1(config-router)#network 1.1.1.1 0.0.0.0 area 0 R1(config-router)#network 100.100.100.1 0.0.0.0 area 100 R1(config-router)#network 100.100.100.2 0.0.0.0 area 100 R1(config-router)#network 100.100.100.3 0.0.0.0 area 100 R1(config-router)#network 12.12.12.1 0.0.0.0 area 0 R1(config-router)#redistribute eigrp 10 subnets
R2 ===== R2(config)#int lo0 R2(config-if)#ip add 2.2.2.2 255.255.255.255 R2(config)#int gig0/0 R2(config-if)#ip add 12.12.12.2 255.255.255.0 R2(config-if)#no sh R2(config)#int g0/1 R2(config-if)#ip add 23.23.23.2 255.255.255.0 R2(config-if)#no sh R2(config)#router ospf 2 R2(config-router)#router-id 2.2.2.2 R2(config-router)#network 2.2.2.2 0.0.0.0 area 1 R2(config-router)#network 12.12.12.2 0.0.0.0 area 0 R2(config-router)#network 23.23.23.2 0.0.0.0 area 1
R3 ===== R3(config)#int lo0 R3(config-if)#ip add 3.3.3.3 255.255.255.255 R3(config-if)#int g0/1 R3(config-if)#ip add 23.23.23.3 255.255.255.0 R3(config-if)#no sh R3(config-if)#exit R3(config)#int lo1 R3(config-if)#ip add 33.33.33.1 255.255.255.255 R3(config-if)#int lo2 R3(config-if)#ip add 33.33.33.2 255.255.255.255 R3(config-if)#int lo3 R3(config-if)#ip add 33.33.33.3 255.255.255.255 R3(config)#router rip R3(config-router)#version 2 R3(config-router)#network 33.33.33.0 R3(config-router)#no auto-summary R3(config)#router ospf 3 R3(config-router)#router-id 3.3.3.3 R3(config-router)#network 3.3.3.3 0.0.0.0 area 1 R3(config-router)#network 23.23.23.3 0.0.0.0 area 1 R3(config-router)#redistribute rip subnets
Tabel routing R3 tanpa NSSA/Totally NSSA
=====
R3#show ip route ospf
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
a - application route
+ - replicated route, % - next hop override, p - overrides from PfR
Gateway of last resort is not set
1.0.0.0/32 is subnetted, 1 subnets
O IA 1.1.1.1 [110/3] via 23.23.23.2, 00:02:02, GigabitEthernet0/1
2.0.0.0/32 is subnetted, 1 subnets
O 2.2.2.2 [110/2] via 23.23.23.2, 00:02:02, GigabitEthernet0/1
12.0.0.0/24 is subnetted, 1 subnets
O IA 12.12.12.0 [110/2] via 23.23.23.2, 00:02:02, GigabitEthernet0/1
100.0.0.0/32 is subnetted, 7 subnets
O IA 100.100.100.1 [110/3] via 23.23.23.2, 00:02:02, GigabitEthernet0/1
O IA 100.100.100.2 [110/3] via 23.23.23.2, 00:02:02, GigabitEthernet0/1
O IA 100.100.100.3 [110/3] via 23.23.23.2, 00:02:02, GigabitEthernet0/1
O E2 100.100.100.4 [110/20] via 23.23.23.2, 00:02:02, GigabitEthernet0/1
O E2 100.100.100.5 [110/20] via 23.23.23.2, 00:02:02, GigabitEthernet0/1
O E2 100.100.100.6 [110/20] via 23.23.23.2, 00:02:02, GigabitEthernet0/1
O E2 100.100.100.7 [110/20] via 23.23.23.2, 00:02:02, GigabitEthernet0/1
=====
LSA Database R3 tanpa NSSA/Totally NSSA
=====
R3#show ip ospf database
OSPF Router with ID (3.3.3.3) (Process ID 3)
Router Link States (Area 1)
Link ID ADV Router Age Seq# Checksum Link count
2.2.2.2 2.2.2.2 141 0x80000002 0x0078FF 2
3.3.3.3 3.3.3.3 72 0x80000003 0x0069FF 2
Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
23.23.23.3 3.3.3.3 141 0x80000001 0x00B21F
Summary Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
1.1.1.1 2.2.2.2 164 0x80000001 0x0033FB
12.12.12.0 2.2.2.2 173 0x80000002 0x00A36B
100.100.100.1 2.2.2.2 164 0x80000001 0x0039CB
100.100.100.2 2.2.2.2 164 0x80000001 0x002FD4
100.100.100.3 2.2.2.2 164 0x80000001 0x0025DD
Summary ASB Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
1.1.1.1 2.2.2.2 164 0x80000001 0x001B14
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
33.33.33.1 3.3.3.3 71 0x80000001 0x00DA55 0
33.33.33.2 3.3.3.3 71 0x80000001 0x00D05E 0
33.33.33.3 3.3.3.3 71 0x80000001 0x00C667 0
100.100.100.4 1.1.1.1 214 0x80000001 0x0083E7 0
100.100.100.5 1.1.1.1 214 0x80000001 0x0079F0 0
100.100.100.6 1.1.1.1 214 0x80000001 0x006FF9 0
100.100.100.7 1.1.1.1 214 0x80000001 0x006503 0
Tabel Routing R1 tanpa NSSA/Totally NSSA
=====
R1#show ip route ospf
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
a - application route
+ - replicated route, % - next hop override, p - overrides from PfR
Gateway of last resort is not set
2.0.0.0/32 is subnetted, 1 subnets
O IA 2.2.2.2 [110/2] via 12.12.12.2, 00:06:05, GigabitEthernet0/0
3.0.0.0/32 is subnetted, 1 subnets
O IA 3.3.3.3 [110/3] via 12.12.12.2, 00:05:29, GigabitEthernet0/0
23.0.0.0/24 is subnetted, 1 subnets
O IA 23.23.23.0 [110/2] via 12.12.12.2, 00:06:05, GigabitEthernet0/0
33.0.0.0/32 is subnetted, 3 subnets
O E2 33.33.33.1 [110/20] via 12.12.12.2, 00:04:17, GigabitEthernet0/0
O E2 33.33.33.2 [110/20] via 12.12.12.2, 00:04:17, GigabitEthernet0/0
O E2 33.33.33.3 [110/20] via 12.12.12.2, 00:04:17, GigabitEthernet0/0
=====
LSA Database R1 tanpa NSSA/Totally NSSA
=====
R1# show ip ospf database
OSPF Router with ID (1.1.1.1) (Process ID 1)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count
1.1.1.1 1.1.1.1 439 0x80000002 0x00C6FF 2
2.2.2.2 2.2.2.2 440 0x80000002 0x00577D 1
Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
12.12.12.2 2.2.2.2 440 0x80000001 0x0014EB
Summary Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
2.2.2.2 2.2.2.2 476 0x80000001 0x00FA31
3.3.3.3 2.2.2.2 400 0x80000001 0x00D650
23.23.23.0 2.2.2.2 476 0x80000001 0x0018D6
100.100.100.1 1.1.1.1 480 0x80000001 0x004DBC
100.100.100.2 1.1.1.1 480 0x80000001 0x0043C5
100.100.100.3 1.1.1.1 480 0x80000001 0x0039CE
Summary ASB Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
3.3.3.3 2.2.2.2 333 0x80000001 0x00BE68
Router Link States (Area 100)
Link ID ADV Router Age Seq# Checksum Link count
1.1.1.1 1.1.1.1 485 0x80000001 0x003641 3
Summary Net Link States (Area 100)
Link ID ADV Router Age Seq# Checksum
1.1.1.1 1.1.1.1 480 0x80000001 0x0047EC
2.2.2.2 1.1.1.1 435 0x80000001 0x00230C
3.3.3.3 1.1.1.1 399 0x80000001 0x00FE2B
12.12.12.0 1.1.1.1 480 0x80000001 0x00C350
23.23.23.0 1.1.1.1 435 0x80000001 0x0040B1
Summary ASB Link States (Area 100)
Link ID ADV Router Age Seq# Checksum
3.3.3.3 1.1.1.1 332 0x80000001 0x00E643
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
33.33.33.1 3.3.3.3 338 0x80000001 0x00DA55 0
33.33.33.2 3.3.3.3 338 0x80000001 0x00D05E 0
33.33.33.3 3.3.3.3 338 0x80000001 0x00C667 0
100.100.100.4 1.1.1.1 485 0x80000001 0x0083E7 0
100.100.100.5 1.1.1.1 485 0x80000001 0x0079F0 0
100.100.100.6 1.1.1.1 485 0x80000001 0x006FF9 0
100.100.100.7 1.1.1.1 485 0x80000001 0x006503 0
Kemudian pada R1, Prefix 33.33.33.x juga masuk di LSA Type-5, Pada R1 nantinya Prefix 33.33.33.x tersebut akan tetap pada LSA Type-5 karena pada R1 tidak mengaktifkan NSSA area, Sehingga R1 tetap mengetahui Informasi-informasi LSA Type-5 yaitu IP Prefix external link dan juga router yang mengadvertise prefix tersebut yaitu router-id 3.3.3.3 (R3).Lab NSSA Area
NSSA Area ===== ===== R2 ===== R2(config)#router ospf 2 R2(config-router)#area 1 nssa R2(config-router)#area 1 nssa default-information-originate *Aug 5 04:01:19.875: %OSPF-5-ADJCHG: Process 2, Nbr 3.3.3.3 on GigabitEthernet0/1 from FULL to DOWN, Neighbor Down: Adjacency forced to reset ===== R3 ===== R3(config)#router ospf 3 R3(config-router)#area 1 nssa *Aug 5 04:03:06.003: %OSPF-5-ADJCHG: Process 3, Nbr 2.2.2.2 on GigabitEthernet0/1 from LOADING to FULL, Loading DoneBaik saat ini kita sudah mengaktifkan NSSA Area pada area 1, Kemudian untuk default-information-originate digunakan untuk memberikan default route pada R3 agar dapat reachable mangakses prefix yang di advertise oleh R1 yaitu IP EIGRP yang di redistribute. Jika tidak ada default route tentu kita tidak akan berkomunikasi dengan prefix tersebut karena informasi prefix tersebut sudah dibuang dari LSA Type-5 R3.
Verifikasi NSSA Area
Verifikasi NSSA Area
=====
=====
Routing Table R3
=====
R3#show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
a - application route
+ - replicated route, % - next hop override, p - overrides from PfR
Gateway of last resort is 23.23.23.2 to network 0.0.0.0
O*N2 0.0.0.0/0 [110/1] via 23.23.23.2, 00:04:19, GigabitEthernet0/1
1.0.0.0/32 is subnetted, 1 subnets
O IA 1.1.1.1 [110/3] via 23.23.23.2, 00:04:19, GigabitEthernet0/1
2.0.0.0/32 is subnetted, 1 subnets
O 2.2.2.2 [110/2] via 23.23.23.2, 00:04:19, GigabitEthernet0/1
3.0.0.0/32 is subnetted, 1 subnets
C 3.3.3.3 is directly connected, Loopback0
12.0.0.0/24 is subnetted, 1 subnets
O IA 12.12.12.0 [110/2] via 23.23.23.2, 00:04:19, GigabitEthernet0/1
23.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 23.23.23.0/24 is directly connected, GigabitEthernet0/1
L 23.23.23.3/32 is directly connected, GigabitEthernet0/1
33.0.0.0/32 is subnetted, 3 subnets
C 33.33.33.1 is directly connected, Loopback1
C 33.33.33.2 is directly connected, Loopback2
C 33.33.33.3 is directly connected, Loopback3
100.0.0.0/32 is subnetted, 3 subnets
O IA 100.100.100.1 [110/3] via 23.23.23.2, 00:04:19, GigabitEthernet0/1
O IA 100.100.100.2 [110/3] via 23.23.23.2, 00:04:19, GigabitEthernet0/1
O IA 100.100.100.3 [110/3] via 23.23.23.2, 00:04:19, GigabitEthernet0/1
=====
Verifikasi ping R3
=====
R3#ping 100.100.100.4
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 100.100.100.4, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 3/3/5 ms
R3#ping 100.100.100.5
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 100.100.100.5, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 3/4/5 ms
=====
LSA Database R3
=====
R3#show ip ospf database
OSPF Router with ID (3.3.3.3) (Process ID 3)
Router Link States (Area 1)
Link ID ADV Router Age Seq# Checksum Link count
2.2.2.2 2.2.2.2 298 0x80000004 0x00204E 2
3.3.3.3 3.3.3.3 297 0x80000005 0x000B56 2
Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
23.23.23.3 3.3.3.3 293 0x80000003 0x005475
Summary Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
1.1.1.1 2.2.2.2 401 0x80000002 0x00D651
12.12.12.0 2.2.2.2 401 0x80000003 0x0047C0
100.100.100.1 2.2.2.2 401 0x80000002 0x00DC21
100.100.100.2 2.2.2.2 401 0x80000002 0x00D22A
100.100.100.3 2.2.2.2 401 0x80000002 0x00C833
Type-7 AS External Link States (Area 1)
Link ID ADV Router Age Seq# Checksum Tag
0.0.0.0 2.2.2.2 385 0x80000001 0x00D0D8 0
33.33.33.1 3.3.3.3 298 0x80000001 0x00DC3D 0
33.33.33.2 3.3.3.3 298 0x80000001 0x00D246 0
33.33.33.3 3.3.3.3 298 0x80000001 0x00C84F 0
Sekarang dapat kita lihat, Setelah mengaktifkan NSSA Area tabel routing pada R3 tidak ada Prefix External Links yang di redistribute oleh R1 bukan? Hanya ada default route yang di generate oleh NSSA default-information-originate sebelumnya. Namun jika kita ping ke arah prefix tersebut link dapat berkomunikasi dengan redistribute tersebut. Selanjutnya kita lihat pada LSA Database di R3, External Links yang di redistribute R1 dengan prefix 100.100.100.x > 3 - 7] tersebut di konversi menjadi default route, Dann juga Prefix 33.33.33.x yaitu prefix dari RIP yang di redistribute oleh R3 sendiri sekarang menjadi Type-7, Point ini lah yang paling penting dari penggunaan NSSA Area. NSSA Menolak keberadaan dari LSA Type-5 namun mengganti nya menjadi Type-7 tersebut.
Verifikasi NSSA Area
=====
=====
Routing Table R1
=====
R1#show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
a - application route
+ - replicated route, % - next hop override, p - overrides from PfR
Gateway of last resort is not set
1.0.0.0/32 is subnetted, 1 subnets
C 1.1.1.1 is directly connected, Loopback0
2.0.0.0/32 is subnetted, 1 subnets
O IA 2.2.2.2 [110/2] via 12.12.12.2, 00:31:03, GigabitEthernet0/0
3.0.0.0/32 is subnetted, 1 subnets
O IA 3.3.3.3 [110/3] via 12.12.12.2, 00:12:58, GigabitEthernet0/0
12.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 12.12.12.0/24 is directly connected, GigabitEthernet0/0
L 12.12.12.1/32 is directly connected, GigabitEthernet0/0
23.0.0.0/24 is subnetted, 1 subnets
O IA 23.23.23.0 [110/2] via 12.12.12.2, 00:12:58, GigabitEthernet0/0
33.0.0.0/32 is subnetted, 3 subnets
O E2 33.33.33.1 [110/20] via 12.12.12.2, 00:12:57, GigabitEthernet0/0
O E2 33.33.33.2 [110/20] via 12.12.12.2, 00:12:57, GigabitEthernet0/0
O E2 33.33.33.3 [110/20] via 12.12.12.2, 00:12:57, GigabitEthernet0/0
100.0.0.0/32 is subnetted, 7 subnets
C 100.100.100.1 is directly connected, Loopback1
C 100.100.100.2 is directly connected, Loopback2
C 100.100.100.3 is directly connected, Loopback3
C 100.100.100.4 is directly connected, Loopback4
C 100.100.100.5 is directly connected, Loopback5
C 100.100.100.6 is directly connected, Loopback6
C 100.100.100.7 is directly connected, Loopback7
=====
LSA Database R1
=====
R1#show ip ospf database
OSPF Router with ID (1.1.1.1) (Process ID 1)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count
1.1.1.1 1.1.1.1 1817 0x80000002 0x00C6FF 2
2.2.2.2 2.2.2.2 846 0x80000003 0x005B76 1
Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
12.12.12.2 2.2.2.2 1818 0x80000001 0x0014EB
Summary Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
2.2.2.2 2.2.2.2 1854 0x80000001 0x00FA31
3.3.3.3 2.2.2.2 729 0x80000001 0x00D650
23.23.23.0 2.2.2.2 729 0x80000001 0x0018D6
100.100.100.1 1.1.1.1 1858 0x80000001 0x004DBC
100.100.100.2 1.1.1.1 1858 0x80000001 0x0043C5
100.100.100.3 1.1.1.1 1858 0x80000001 0x0039CE
Router Link States (Area 100)
Link ID ADV Router Age Seq# Checksum Link count
1.1.1.1 1.1.1.1 1863 0x80000001 0x003641 3
Summary Net Link States (Area 100)
Link ID ADV Router Age Seq# Checksum
1.1.1.1 1.1.1.1 1858 0x80000001 0x0047EC
2.2.2.2 1.1.1.1 1812 0x80000001 0x00230C
3.3.3.3 1.1.1.1 728 0x80000001 0x00FE2B
12.12.12.0 1.1.1.1 1858 0x80000001 0x00C350
23.23.23.0 1.1.1.1 728 0x80000001 0x0040B1
Summary ASB Link States (Area 100)
Link ID ADV Router Age Seq# Checksum
2.2.2.2 1.1.1.1 840 0x80000001 0x000B24
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
33.33.33.1 2.2.2.2 728 0x80000001 0x008F98 0
33.33.33.2 2.2.2.2 728 0x80000001 0x0085A1 0
33.33.33.3 2.2.2.2 728 0x80000001 0x007BAA 0
100.100.100.4 1.1.1.1 1863 0x80000001 0x0083E7 0
100.100.100.5 1.1.1.1 1863 0x80000001 0x0079F0 0
100.100.100.6 1.1.1.1 1863 0x80000001 0x006FF9 0
100.100.100.7 1.1.1.1 1863 0x80000001 0x006503 0
Selanjutnyaa, Jika kita lihat table routing pada R1 prefix 33.33.33.x yang advertise oleh R3 tidak diubah menjadi default route melainkan tetap dianggap sebagai external links pada R1, Kemudiann jika kita lihat pada LSA Database R1 prefix-prefix EIGRP yang di redistribute tetap dimasukan kedalam LSA Type-5, Tidak seperti di R3 karena area NSSA hanya ada pada area 1.Lab Totally NSSA
Selanjutnya untuk Totally NSSA kita akan meringkas kembali Inter Area pada area NSSA, Sehingga LSA Type-3 hanya berisi default route namun LSA Type-7 tetap berisi prefix dari network yang di redistribute oleh R3 dan juga default route untuk prefix External Links nya. Baik langsung saja.
Lab Totally NSSA ===== ===== R2 ===== R2(config)#router ospf 2 R2(config-router)#area 1 nssa no-summary ===== R3 ===== R3(config)#router ospf 3 R3(config-router)#area 1 nssa no-summaryKita sudah membuat NSSA menjadi Totally NSSA dengan menambahkan no-summary. Maka seharusnya LSA Type-3 untuk Inter Area sudah di ringkas menjadi default route pada LSA Database R3, Mari kita lihat..
Verifikasi Totally NSSA
Verifikasi Totally NSSA
=====
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Routing Table R3
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R3#show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
a - application route
+ - replicated route, % - next hop override, p - overrides from PfR
Gateway of last resort is 23.23.23.2 to network 0.0.0.0
O*IA 0.0.0.0/0 [110/2] via 23.23.23.2, 00:06:41, GigabitEthernet0/1
2.0.0.0/32 is subnetted, 1 subnets
O 2.2.2.2 [110/2] via 23.23.23.2, 00:06:41, GigabitEthernet0/1
3.0.0.0/32 is subnetted, 1 subnets
C 3.3.3.3 is directly connected, Loopback0
23.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 23.23.23.0/24 is directly connected, GigabitEthernet0/1
L 23.23.23.3/32 is directly connected, GigabitEthernet0/1
33.0.0.0/32 is subnetted, 3 subnets
C 33.33.33.1 is directly connected, Loopback1
C 33.33.33.2 is directly connected, Loopback2
C 33.33.33.3 is directly connected, Loopback3
=====
LSA Database R3
=====
R3#show ip ospf database
OSPF Router with ID (3.3.3.3) (Process ID 3)
Router Link States (Area 1)
Link ID ADV Router Age Seq# Checksum Link count
2.2.2.2 2.2.2.2 193 0x80000005 0x001E4F 2
3.3.3.3 3.3.3.3 162 0x80000006 0x000957 2
Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
23.23.23.3 3.3.3.3 162 0x80000004 0x005276
Summary Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
0.0.0.0 2.2.2.2 439 0x80000001 0x00FC31
Type-7 AS External Link States (Area 1)
Link ID ADV Router Age Seq# Checksum Tag
0.0.0.0 2.2.2.2 193 0x80000002 0x00CED9 0
33.33.33.1 3.3.3.3 162 0x80000002 0x00DA3E 0
33.33.33.2 3.3.3.3 162 0x80000002 0x00D047 0
33.33.33.3 3.3.3.3 162 0x80000002 0x00C650 0
Baiikk mari kita lihatt, Pada routing table R3 bagaimana?? Sangatt ringkas seperti Stub bukan? Prefix dari Inter Area dan Juga External Links di konversi menjadi default route saja. Kemudian kita lihat juga pada LSA Database di R3, Pertama untuk LSA Type-3 yaitu Summary semua di konversi langsungg menjadi default route, Kemudian untuk prefix 33.33.33.x yang mana harusnya menjadi LSA Type-5 yaitu External Links yang di advertise oleh R3 tetap bisaa diketahui dengan LSA Type yang berbeda yaitu Type-7, Kemudian untuk External Links dari EIGRP yang digenerate oleh R1 dikonversi juga menjadi default route didalam Type-7.
Kesimpulan
Kita sudah membahas 2 area spesial pada OSPF yaitu Stub dan sekarang NSSA, Perbedaan NSSA dengan Stub adalah NSSA akan mengizinkan prefix yang di redistribute oleh ASBR namun bukan dengan LSA Type-5 melainkan dengan LSA Type-7, Kenapa tidak dengan LSA Type-5? Karena LSA Type-5 tidak diizinkan dalam Stub area yang mana pada dasarnya NSSA adalah termasuk Stub juga namun tetap mengizinkan Prefix External Links dengan LSA Type yang berbeda.
Oke itu tentang NSSA (Not So Stubby Area), Semoga bisa dipahami dan bermanfaat..Seperti biasa,
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