目標：在r1，r4和r5之間的幀中繼網路中配置ospf，網路型別為broadcast，實現vlan a， vlan b和vlan c的互通
配置指南：
在r1上配置介面ether***0/0位址為1.0.0.1/8
在r4上配置介面ether***0/0位址為4.0.0.4/8
在r5上配置介面ether***0/0位址為5.0.0.5/8
在r1上配置介面seria0/0位址為10.0.0.1/8
在r4上配置介面serial0/0位址為10.0.0.4/8
在r5上配置介面serial0/0位址為10.0.0.5/8
在r1，r4和r5的serial介面上配置幀中繼封裝
在r4和r5上禁用幀中繼反向位址解析
在r1上配置靜態對映，通過dcli104到10.0.0.4和通過dlci105到10.0.0.5
在r4上配置靜態對映，通過dlci401到10.0.0.1和10.0.0.5
在r5上配置靜態對映，通過dlci501到10.0.0.1 和10.0.0.4
確保鏈路支援廣播和多播資料報傳遞
在r1， r4， 和r5的serial介面上配置ospf網路型別為broadcast
在r4和r5配置serial介面ospf優先順序為0
配置r1， r4和r5中所有介面加入area 0
自我提問：
broadcast的網路型別和其他網路型別有什麼不同？
這種網路型別中lsa是單播還是組播發送？
這種網路型別支援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:inte***ce ether***0/0
ip address 1.0.0.1 255.0.0.0
!inte***ce serial0/0
ip address 10.0.0.1 255.0.0.0
encapsulation frame-relay
ip ospf ***work broadcast
frame-relay map ip 10.0.0.4 104 broadcast
frame-relay map ip 10.0.0.5 105 broadcast
!router ospf 1
***work 0.0.0.0 255.255.255.255 area 0
r4:inte***ce ether***0/0
ip address 4.0.0.4 255.0.0.0
!inte***ce serial0/0
ip address 10.0.0.4 255.0.0.0
encapsulation frame-relay
ip ospf ***work 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
***work 0.0.0.0 255.255.255.255 area 0
r5:inte***ce ether***0/0
ip address 5.0.0.5 255.0.0.0
!inte***ce serial0/0
ip address 10.0.0.5 255.0.0.0
encapsulation frame-relay
ip ospf ***work 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
***work 0.0.0.0 255.255.255.255 area 0
r1#show ip ospf neighbor
neighbor id pri state dead time address inte***ce
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 inte***ce
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 inte***ce
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, ether***0/0
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, ether***0/0
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, ether***0/0
c 10.0.0.0/8 is directly connected, serial0/0
註解：在網路型別為broadcast的網路中ospf hellos包是通過組播傳遞，像non-broadcast的網路型別一樣需要dr/bdr 的選舉。對於以太網路或者令牌網這種廣播型網路來說，這種是預設的網路型別。需要注意的是本例中的framerelay map命令增加了broadcast選項，這是因為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順序配置問題，略過。