Bài 1: Configuring ospf virtual link

Bài 1 : Configuring OSPF Virtual Link Mục đích : cấu hình để cho một vùng không có liên lạc với backbone có thể liên lạc được. Cấu hình : + Diagram: Click this bar to view the small image. + Chi tiết : SanJose1#sh run Building configuration… Current configuration : 1015 bytes ! version 12.4 service timestamps debug datetime msec service timestamps log datetime msec no service password-encryption ! hostname SanJose1 ! boot-start-marker boot-end-marker ! enable secret 5 $1$bP5E$pamhnCUi0AcSl/F9Rej651 ! no aaa new-model ! resource policy ! ip cef ! interface Loopback0 ip address 192.168.1.3 255.255.255.0 ! interface Loopback1 ip address 192.168.0.3 255.255.255.0 ! interface FastEthernet0/0 ip address 192.168.224.1 255.255.255.0 duplex half ! router ospf 1 log-adjacency-changes network 192.168.0.0 0.0.0.255 area 0 network 192.168.1.0 0.0.0.255 area 0 network 192.168.224.0 0.0.0.255 area 51 ! no ip http server no ip http secure-server ! logging alarm informational ! control-plane ! gatekeeper shutdown ! ! line con 0 exec-timeout 0 0 password cisco logging synchronous login stopbits 1 line aux 0 stopbits 1 line vty 0 4 exec-timeout 0 0 password cisco logging synchronous login ! ! end SanJose1# Singapore#sh run Building configuration… Current configuration : 1790 bytes ! version 12.4 service timestamps debug datetime msec service timestamps log datetime msec no service password-encryption ! hostname Singapore ! boot-start-marker boot-end-marker ! enable secret 5 $1$bPdv$hcFIbsP8L4rzFyuNrFoqE0 ! no aaa new-model ! resource policy ! ip cef ! interface Loopback0 ip address 192.168.3.1 255.255.255.0 ! interface FastEthernet0/0 ip address 192.168.224.2 255.255.255.0 duplex half ! interface Serial1/0 ip address 192.168.240.1 255.255.255.252 serial restart-delay 0 no dce-terminal-timing-enable ! interface Serial1/1 no ip address shutdown serial restart-delay 0 no dce-terminal-timing-enable ! interface Serial1/2 no ip address shutdown serial restart-delay 0 no dce-terminal-timing-enable ! interface Serial1/3 no ip address shutdown serial restart-delay 0 no dce-terminal-timing-enable ! interface Serial1/4 no ip address shutdown serial restart-delay 0 no dce-terminal-timing-enable ! interface Serial1/5 no ip address shutdown serial restart-delay 0 no dce-terminal-timing-enable ! interface Serial1/6 no ip address shutdown serial restart-delay 0 no dce-terminal-timing-enable ! interface Serial1/7 no ip address shutdown serial restart-delay 0 no dce-terminal-timing-enable ! router ospf 1 log-adjacency-changes network 192.168.3.0 0.0.0.255 area 51 network 192.168.224.0 0.0.0.255 area 51 network 192.168.240.0 0.0.0.3 area 3 ! no ip http server no ip http secure-server ! logging alarm informational ! control-plane ! gatekeeper shutdown ! ! line con 0 exec-timeout 0 0 password cisco logging synchronous login stopbits 1 line aux 0 stopbits 1 line vty 0 4 exec-timeout 0 0 password cisco logging synchronous login ! ! end Singapore# Auckland#sh run Building configuration… Current configuration : 1711 bytes ! version 12.4 service timestamps debug datetime msec service timestamps log datetime msec no service password-encryption ! hostname Auckland ! boot-start-marker boot-end-marker ! enable secret 5 $1$W3Ux$X4cR/1jc27f9IbV5b.Qgn0 ! no aaa new-model ! resource policy ! ip cef ! interface Loopback0 ip address 192.168.252.1 255.255.255.0 ! interface FastEthernet0/0 ip address 192.168.248.1 255.255.255.0 duplex half ! interface Serial1/0 ip address 192.168.240.2 255.255.255.252 serial restart-delay 0 no dce-terminal-timing-enable ! interface Serial1/1 no ip address shutdown serial restart-delay 0 no dce-terminal-timing-enable ! interface Serial1/2 no ip address shutdown serial restart-delay 0 no dce-terminal-timing-enable ! interface Serial1/3 no ip address shutdown serial restart-delay 0 no dce-terminal-timing-enable ! interface Serial1/4 no ip address shutdown serial restart-delay 0 no dce-terminal-timing-enable ! interface Serial1/5 no ip address shutdown serial restart-delay 0 no dce-terminal-timing-enable ! interface Serial1/6 no ip address shutdown serial restart-delay 0 no dce-terminal-timing-enable ! interface Serial1/7 no ip address shutdown serial restart-delay 0 no dce-terminal-timing-enable ! router ospf 1 log-adjacency-changes network 192.168.240.0 0.0.0.3 area 3 ! no ip http server no ip http secure-server ! ! ! logging alarm informational ! control-plane ! gatekeeper shutdown ! ! line con 0 exec-timeout 0 0 password cisco logging synchronous login stopbits 1 line aux 0 stopbits 1 line vty 0 4 exec-timeout 0 0 password cisco logging synchronous login ! ! end Auckland# Auckland#sh ip route Codes: 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 Gateway of last resort is not set 192.168.240.0/30 is subnetted, 1 subnets C 192.168.240.0 is directly connected, Serial1/0 C 192.168.252.0/24 is directly connected, Loopback0 Auckland# Ta nhận thấy rằng không có route nào được được học bởi OSPF được phân phối vào router Auckland. Notes : Bạn nên nhớ rằng, mặc dù area 51 và 3 là thân mật với nhau nhưng để ospf route được updates thì inter area traffic phải được vận chuyển thông đến vùng backbone Router Singapore là một ABR của vùng 3 , router SanJose1 là ABR của vùng 0 (backbone). Vì vậy , để hoàn thành mục đích : ospf route được update vào area 3 thì ta cần phải cấu hình "virtual link" trên Singapore và SanJose1 thông qua area 51 như một "vùng trung chuyển" (transit area) Code: SanJose1: ! router ospf 1 log-adjacency-changes area 51 virtual-link 192.168.3.1 (Đây là router’s RID của Singapore) network 192.168.0.0 0.0.0.255 area 0 network 192.168.1.0 0.0.0.255 area 0 network 192.168.224.0 0.0.0.255 area 51 ! Code: Singapore: ! router ospf 1 log-adjacency-changes area 51 virtual-link 192.168.1.3 network 192.168.3.0 0.0.0.255 area 51 network 192.168.224.0 0.0.0.255 area 51 network 192.168.240.0 0.0.0.3 area 3 Kết quả : Auckland#sh ip route Codes: C - connected, S - static, R D - EIGRP, EX - EIGRP external, O N1 - OSPF NSSA external type 1, N2 E1 - OSPF external type 1, E2 - OSPF external type 2 i - IS-IS, su - IS-IS summary, L1 ia - IS-IS inter area, * - candidate default, U o - ODR, P - periodic downloaded static route Gateway of last resort is not set O IA 192.168.224.0/24 [110/65] via 19 192.168.240.0/30 is subnetted, 1 subnets C 192.168.240.0 is directly connected, Serial1/0 192.168.0.0/32 is subnetted, 1 subnets O IA 192.168.0.3 [110/66] via 192.168.240.1, 00:00:01, Serial1/0 192.168.1.0/32 is subnetted, 1 subnets O IA 192.168.1.3 [110/66] via 192.168.240.1, 00:00:01, Serial1/0 C 192.168.252.0/24 is directly connected, Loopback0 192.168.3.0/32 is subnetted, 1 subnets O IA 192.168.3.1 [110/65] via 192.168.240.1, 00 Ngoài ra để xem "virtual link" bạ Code: #sh ip ospf virtual-links Tóm lại : == virtual links phải được cấu h vùng trung chuyển (transit area) == inter area traffic phài được chuy (Đây là router’s RID của Sanjose1) - RIP, M - mobile, B - BGP - OSPF, IA - OSPF inter area - OSPF NSSA external type 2 - IS-IS level-1, L2 - IS-IS level-2 - per-user static route 2.168.240.1, 00 32, Serial1/0 32, Serial1/0 n dùng thêm lệnh : ình trên cả 2 con router ngoài cùng (edge router) trong ển đến vùng backbone.