26. OSPF AREA 개념( ABR, ASBR,IR )

그림 1

ABR - ospf의 area 경계에 있는 것

ASBR - 다른 프로토콜 경계에 있는 것

IR - ospf에만 속해 있는 것

 

ASBR에는 외부의 프로토콜의 축약을 적고 ABR에는 area내의 주소를 축약한 것을 적어줄 수 있다.

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ASBR

router ospf 1
summary-address [축약네트워크] [서브넷 마스크]

ASBR에 다른 프로토콜의 주소를 축약한다는 것을 적어주게 되면 다른 라우터로 전송할때 축약된 라우팅 테이블을 갖게 됩니다.

 

ABR

router ospf 1
area [area number] range [축약네트워크] [서브넷 마스크]

ABR에서 위의 명령어를 적어주었을 때, 다른 ospf area 로 주소가 넘어갈 때 축약되어 주소가 넘어가게 됩니다.

 

A 192.168.10.0 ~ 127                            1 ~126
B 192.168.10.128 ~ 255                       129 ~ 254      255.255.255.128

C 193.168.10.0 ~ 127                           1 ~126

D 193.168.10.128 ~ 255                      129 ~ 254      255.255.255.128

E 194.168.10.0 ~ 194.168.10.127        1~ 126           255.255.255.128 

F 194.168.10.128 ~ 194.168.10.191    129 ~ 190      255.255.255.192 

G 194.168.10.192 ~ 194.168.10.223    193 ~ 222     255.255.255.224 

 그림 1의 각 라우터 작성 내용

<R1>

Router(config-if)#int e0/0 
Router(config-if)#ip add 192.168.10.126 255.255.255.128
Router(config-if)#no sh 
Router(config-if)#exit

Router(config)#int e0/1 
Router(config-if)#ip add 192.168.10.254 255.255.255.128 
Router(config-if)#no sh 
Router(config-if)#exit 

Router(config)#int s1/0
Router(config-if)#ip add 1.1.13.1 255.255.255.0
Router(config-if)#no sh 
Router(config-if)#exit 

Router(config)#router ospf 1
Router(config-router)#network 192.168.10.0 0.0.0.255 area 10
Router(config-router)#network 1.1.13.0 0.0.0.255 area 10 
Router(config-router)#exit

 

<R2>

Router(config)#int e0/0 
Router(config-if)#ip add 193.168.10.126 255.255.255.128 
Router(config-if)#no sh
Router(config-if)#exit

R2(config)#int e0/1 
R2(config-if)#ip add 193.168.10.254 255.255.255.128
R2(config-if)#no sh 
R2(config-if)#exit

R2(config)#int s1/1 
R2(config-if)#ip add 1.1.23.1 255.255.255.0 
R2(config-if)#no sh
R2(config-if)#exit 

R2(config)#router ospf 1
R2(config-router)#network 193.168.10.0 0.0.0.255 area 20 
R2(config-router)#network 1.1.23.0 0.0.0.255 area 20

 

<R3>

R3(config)#router ospf 1 
R3(config-router)#network 1.1.13.0 0.0.0.255 area 10 
R3(config-router)#network 1.1.34.0 0.0.0.255 area 0 
R3(config-router)#network 1.1.23.0 0.0.0.255 area 20 
R3(config-router)#area 10 range 192.168.10.0 255.255.255.0
R3(config-router)#area 20 range 193.168.10.0 255.255.255.0

<R4>

router ospf 1 area 30 range 194.168.10.0 255.255.255.0 
network 1.1.34.0 0.0.0.255 area 0 
network 1.1.45.0 0.0.0.255 area 30
network 1.1.46.0 0.0.0.255 area 30

<R5>

R5(config)#router ospf 1 
R5(config-router)#network 194.168.10.0 0.0.0.127 area 30 
R5(config-router)#network 194.168.10.128 0.0.0.63 area 30 
R5(config-router)#network 1.1.45.0 0.0.0.255 area 30

 

<R6>

router ospf 1 network 1.1.46.0 0.0.0.255 area 30 
network 1.1.67.0 0.0.0.255 area 30 
network 194.168.10.192 0.0.0.31 area 30

 

<R7>

R7(config)#int e0/0
R7(config-if)#ip add 1.1.67.254 255.255.255.0 
R7(config-if)#no sh 
R7(config-if)#exit 
R7(config)#int e0/1 
R7(config-if)#ip add 195.168.10.254 255.255.255.0
R7(config-if)#no sh 
R7(config-if)#exit 
interface Serial1/0 ip address 1.1.78.1 255.255.255.0 
ip summary-address eigrp 100 194.168.10.0 255.255.255.0
serial restart-delay 0 
router eigrp 100 
network 1.1.78.0 0.0.0.255
network 195.168.10.0 
redistribute ospf 1 metric 1 1 1 1 1

router ospf 1 
area 30 range 194.168.10.0 255.255.255.0 
summary-address 195.168.0.0 255.255.224.0
redistribute eigrp 100 metric 20 subnets
network 1.1.67.0 0.0.0.255 area 30

 

<R8>

R8(config)#router eigrp 100 
R8(config-router)#network 195.168.20.0 0.0.0.255
R8(config-router)#network 1.1.78.0 0.0.0.255 
R8(config-router)#no au 
R8(config-router)#exit

OSPF Default Route 생성 하기

<방법 1>
ip route 0.0.0.0 0.0.0.0 1.1.34.4
router ospf 1
default-information originate (metric 100 metric-type 1)

<방법2>
router ospf 1
default-information originate always

 

R7(config)#router ospf 1
R7(config-router)#default-information originate always

 

R6(config)#ip route 0.0.0.0 0.0.0.0 1.1.67.254

R6(config)#router ospf 1
R6(config-router)#default-information or
R6(config-router)#default-information originate