Ospf

distrubute routing information within a single autonomous system

 OSPF cost=带宽/100M (也可以强行设置 ip ospf cost )  OSPF 中area 0 作为backbone

 routes that are generated from within an area ( the destination belongs to the area)

are called intra-area routes. 这类路由在路由表中用O表示

 routes that originate from other areas are called inter-area or summary routes. 这类路由在路由表中用O IA表示

 routes that originate from other routing protocols (or different ospf process ) and

that are inject into ospf via redistribution are called external routes. 这类路由在路由表中用O E1 或O E2表示

E1、E2(external type1&external type 2)是计算cost的两种方法，E2只计算ASBR与外部之间的cost,E1还要加上ospf内部的cost), 缺省为E2

1. Enable OSPF on router

router OSPF

network (mask contain wild card bits where 0 is match and 1 is \"don't care\" bit) 例:

router ospf 100

network 192.213.0.0 0.0.255.255 area 0.0.0.0 network 128.213.1.1 0.0.0.0 area 23

2. OSPF Authentication

Null authentication、simple password authentication、message digest authentication(MD5)

(1)Simple Authentication: ip ospf authentication-key (this go under the specific interface)

area authentication (this go under \"router ospf ) 例:

interface Ethernet 0

ip address 10.10.10.10 255.255.255.0 ip ospf authentication-key mypassword

router ospf 100

network 10.10.0.0 0.0.255.255 area 0 area 0 authentication

(2)MD5 authentication: ip ospf message-digest-key md5 (use

under the interface)

area authentication message-digest (use under \"router ospf ) 例：

interface ethernet 0

ip address 10.10.10.10 255.255.255.0

ip ospf message-digest-key 10 md5 mypassword

router ospf 100

network 10.10.0.0 0.0.255.255 area 0 area 0 authentication message-digest

3. virtual link

(use for two purpose : a. link an area that does not have a physical connection to the backbone b. patching the backbone in case discontinuity of area 0 occurs) area virtual-link (area-id 是作为传输的area号，即做virtual link的两个area之间的area, RID是做virtual link 的两个路由器的id ,一般是路由器上最大的ip address或最大的loopback地址） 例:

路由器RTA 地址为1.1.1.1 在area 1 中, 路由器RTB 地址为2.2.2.2 在area 0 中,

area0 和area1 通过area 2 做virtual link. RTA#

router ospf 100

area 2 virtual-link 2.2.2.2 RTB#

router ospf 100

area 2 virtual-link 1.1.1.1

4. Adjacencies:

ip ospf hello-interval ip ospf dead-interval

ip ospf priority (value 值缺省为1，设为0则该路由器不为DR、BDR) sh ip ospf interface , sh ip ospf neighbor 验证

neighbor [priority ] [poll-interval ] (目前已较少使用)

5. NBMA:

(1) point to point subinterface

在物理口上开若干逻辑口实现点对点互连 例:

RTA#:

interface serial 0 no ip address

encapsulation frame-relay

interface serial0.1 point-to-point

ip address 128.213.63.6 255.255.252.0 frame-relay interface-dlci 20

iterface serial0.2 point-to-point

ip address 128.213.64.6 255.255.252.0 frame-relay interface-dlci 30

router ospf 10

network 128.213.0.0 0.0.255.255 area 1

RTB#:

interface serial 0 no ip address

encapsulation frame-relay

interface serial0.1 point-to-point

ip address 128.213.63.5 255.255.252.0 frame-relay interface-dlci 40

interface serial 1

ip address 128.212.1.1 255.255.255.0

router ospf 10

network 128.213.0.0 0.0.255.255 area 1 network 128.212.0.0 0.0.255.255 area 0

(2) Select interface network type:

ip ospf network {broadcast|non-broadcast|point-to-multipoint} 例： RTA#:

interface loopback 0

ip address 200.200.10.1 255.255.255.0

interface serial 0

ip address 128.213.10.1 255.255.252.0 encapsulation frame-relay

ip ospf network point-to-multipoint

router ospf 10

network 128.213.0.0 0.0.255.255 area 1

RTB#:

interface serial 0

ip address 128.213.10.2 255.255.255.0 encapsulation frame-relay

ip ospf network point-to-multipoint

interface serial 1

ip address 123.212.1.1 255.255.255.0

router ospf 10

network 128.213.0.0 0.0.255.255 area 1 network 123.212.0.0 0.0.255.255 area 0

6. OSPF and route summarization

(1) Inter-area route summarization (done on ABRs) area range