目標：
在R1，R4和R5之間的幀中繼網絡中配置OSPF，網絡類型爲broadcast，實現VLAN A， VLAN B和VLAN C的互通
配置指南：
在R1上配置接口Ethernet0/0地址爲1.0.0.1/8
在R4上配置接口Ethernet0/0地址爲4.0.0.4/8
在R5上配置接口Ethernet0/0地址爲5.0.0.5/8
在R1上配置接口Seria0/0地址爲10.0.0.1/8
在R4上配置接口Serial0/0地址爲10.0.0.4/8
在R5上配置接口Serial0/0地址爲10.0.0.5/8
在R1，R4和R5的Serial接口上配置幀中繼封裝
在R4和R5上禁用幀中繼反向地址解析
在R1上配置靜態映射，通過DCLI104到10.0.0.4和通過DLCI105到10.0.0.5
在R4上配置靜態映射，通過DLCI401到10.0.0.1和10.0.0.5
在R5上配置靜態映射，通過DLCI501到10.0.0.1 和10.0.0.4
確保鏈路支持廣播和多播數據包傳遞
在R1， R4， 和R5的Serial接口上配置OSPF網絡類型爲broadcast
在R4和R5配置Serial接口OSPF優先級爲0
配置R1， R4和R5中所有接口加入area 0
自我提問：
broadcast的網絡類型和其他網絡類型有什麼不同?
這種網絡類型中LSA是單播還是組播發送?
這種網絡類型支持DR/BDR 選舉嗎?
這些屬性對配置有什麼影響?
最終配置和驗證：
R1:
interface Ethernet0/0
ip address 1.0.0.1 255.0.0.0
!
interface Serial0/0
ip address 10.0.0.1 255.0.0.0
encapsulation frame-relay
ip ospf network broadcast
frame-relay map ip 10.0.0.4 104 broadcast
frame-relay map ip 10.0.0.5 105 broadcast
!
router ospf 1
network 0.0.0.0 255.255.255.255 area 0
R4:
interface Ethernet0/0
ip address 4.0.0.4 255.0.0.0
!
interface Serial0/0
ip address 10.0.0.4 255.0.0.0
encapsulation frame-relay
ip ospf network broadcast
ip ospf priority 0
frame-relay map ip 10.0.0.1 401 broadcast
frame-relay map ip 10.0.0.5 401
no frame-relay inverse-arp
!
router ospf 1
network 0.0.0.0 255.255.255.255 area 0
R5:
interface Ethernet0/0
ip address 5.0.0.5 255.0.0.0
!
interface Serial0/0
ip address 10.0.0.5 255.0.0.0
encapsulation frame-relay
ip ospf network broadcast
ip ospf priority 0
frame-relay map ip 10.0.0.1 501 broadcast
frame-relay map ip 10.0.0.4 501
no frame-relay inverse-arp
!
router ospf 1
network 0.0.0.0 255.255.255.255 area 0
R1#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
10.0.0.4 0 FULL/DROTHER 00:00:33 10.0.0.4 Serial0/0
10.0.0.5 0 FULL/DROTHER 00:00:36 10.0.0.5 Serial0/0
R4#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
10.0.0.1 1 FULL/DR 00:00:39 10.0.0.1 Serial0/0
R5#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
10.0.0.1 1 FULL/DR 00:00:33 10.0.0.1 Serial0/0
R1#show ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
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
C 1.0.0.0/8 is directly connected, Ethernet0/0
O 4.0.0.0/8 [110/74] via 10.0.0.4, 00:01:49, Serial0/0
O 5.0.0.0/8 [110/74] via 10.0.0.5, 00:01:49, Serial0/0
C 10.0.0.0/8 is directly connected, Serial0/0
R4#show ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
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
O 1.0.0.0/8 [110/74] via 10.0.0.1, 00:02:26, Serial0/0
C 4.0.0.0/8 is directly connected, Ethernet0/0
O 5.0.0.0/8 [110/74] via 10.0.0.5, 00:02:26, Serial0/0
C 10.0.0.0/8 is directly connected, Serial0/0
R5#show ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
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
O 1.0.0.0/8 [110/74] via 10.0.0.1, 00:00:11, Serial0/0
O 4.0.0.0/8 [110/74] via 10.0.0.4, 00:00:11, Serial0/0
C 5.0.0.0/8 is directly connected, Ethernet0/0
C 10.0.0.0/8 is directly connected, Serial0/
註解：
在網絡類型爲broadcast的網絡中OSPF hellos包是通過組播傳遞，像non-broadcast的網絡類型一樣需要DR/BDR 的選舉。對於以太網絡或者令牌網這種廣播型網絡來說，這種是缺省的網絡類型。需要注意的是本例中的framerelay map命令增加了broadcast選項，這是因爲hello包是組播傳遞的。另外由於不是單播所以對於DR和BDR就不需要配置neighbor的命令。同樣還會出現前例講到的優先級配置問題，略過。
通過使用show ip ospf neighbor命令來驗證鄰居關係，使用show ip ospf interface命令來驗證網絡類型和DR/BDR.
關於下一跳的問題也類似前例。