CCNP路由实验(2) -- OSPF

OSPF作为一种内部网关协议(IGP)，用于在同一个AS中的路由器之间交换路由信息。
OSPF的特性如下：
1.可适应大规模网络
2.收敛速度快
3.无路由环路
4.支持VLSM和CIDR
5.支持等价路由
6.支持区域划分，构成结构化的网络
7.提供路由分级管理
8.支持简单口令和MD5认证
9.以组播方式传送协议报文
10.OSPF路由协议的管理距离是110
11.OSPF路由协议采用cost作为度量标准
12.OSPF维护邻居表、拓扑表和路由表

OSPF将网络划分为4中类型：
广播多路访问(BMA)
非广播多路访问(NBMA)
点到点(Point-to-Point)
点到多点(Point-to-MultiPoint)

需要掌握的几个术语：
1.链路：路由器用来连接网络的接口
2.链路状态：用来描述路由器接口及其邻居路由器的关系。所有链路状态信息构成链路状态数据库
3.区域：有相同的区域标识的一组路由器和网络的集合。同一区域内的路由器具有相同的链路状态数据库
4.自治系统：采用同一种路由协议交换路由的路由器及其网络构成一个自治系统
5.链路状态通告(LSA)：LSA用来描述路由器的本地状态，LSA包括的信息有关于路由器接口的状态和所形成的邻接状态

1.多区域的OSPF
   OSPF的DR和BDR选择
2.OSPF汇总
   区域间汇总
   区域外汇总
3.OSPF的网络类型
   点到点网络的网络类型
   广播网络的网络类型
   不同网络类型间相互学习
   NBMA下的OSPF
4.OSPF认证
   OSPF的明文认证
   OSPF的MD5认证
5.OSPF注入默认路由
6.OSPF的特殊区域
   OSPF末节区域
   OSPF完全末节区域
   OSPF次末节区域
   OSPF完全次末节区域
7.OSPF虚电路
   把非骨干区域连接到骨干区域
   不连续的骨干区域
8.OSPF区域间选路

基本配置：
-----------------------------------------------
enable
conf t
no ip do lo
enable pass cisco
line con 0
logg sync
exec-t 0 0
line vty 0 4
pass cisco
logg sync
exit
host

1. 多区域OSPF：
-------------------------------------------------------------------------------

R1:
int f0/0
ip add 12.1.1.1 255.255.255.0
no shut
exit
int l0
ip add 11.1.1.1 255.255.255.0
no shut
exit

router ospf 1
router-id 11.1.1.1
network 12.1.1.0 0.0.0.255 area 1
network 11.1.1.0 0.0.0.255 area 1
exit

R2:
int f0/0
ip add 12.1.1.2 255.255.255.0
no shut
exit
int f1/0
ip add 23.1.1.2 255.255.255.0
no shut
exit
int l0
ip add 22.1.1.1 255.255.255.0
no shut
exit

router ospf 1
router-id 22.1.1.1
network 12.1.1.0 0.0.0.255 area 1
network 22.1.1.0 0.0.0.255 area 0
network 23.1.1.0 0.0.0.255 area 0
exit

R3:
int f0/0
ip add 23.1.1.3 255.255.255.0
no shut
exit
int f1/0
ip add 34.1.1.3 255.255.255.0
no shut
exit
int l0
ip add 33.1.1.1 255.255.255.0
no shut
exit

router ospf 1
router-id 33.1.1.1
network 23.1.1.0 0.0.0.255 area 0
network 33.1.1.0 0.0.0.255 area 0
network 34.1.1.0 0.0.0.255 area 2
exit

R4:
int f0/0
ip add 34.1.1.4 255.255.255.0
no shut
exit
int l0
ip add 44.1.1.1 255.255.255.0
no shut
exit

router ospf 1
router-id 44.1.1.1
network 34.1.1.0 0.0.0.255 area 2
network 44.1.1.0 0.0.0.255 area 2
exit

OSPF路由进程ID的范围必须在1-65535之间，而且只有本地含义，不同路由器的路由进程ID可以不同。如果想要启动OSPF进程，至少需要确保路由器有一个接口是up的。
Area ID是在0-4294967295内的十进制数，可以是IP地址的格式A.B.C.D。当网络Area ID为0或者0.0.0.0时称为主干区域。
在高版本的IOS中通告OSPF网络的时候，网络号的后边可以跟网络掩码，也可以跟反掩码。
确定Router ID顺序如下：优先选定在OSPF进程中用命令"router-id"指定的路由器ID；如果没有指定，则选择IP地址最大的环回接口的IP地址；如果没有环回接口，则选择最大的活动物理接口的IP地址。建议手动指定。

R1:
end
show ip route ospf
conf t
环回接口OSPF路由条目的掩码长度都是32位，这是环回接口的特性，尽管通告了24位。解决的办法是在环回接口下修改网络类型为"Point-to-Point"。其默认网络类型是LOOPBACK，物理接口的默认网络类型是BROADCAST。
R2:
int l0
ip ospf network point-to-point
exit

R1:
end
show ip protocols
show ip ospf int f0/0
show ip ospf neighbor

show ip ospf database

conf t

DR BDR选择
R1:
int f0/0
ip ospf prio 10
exit

R2:
end
show ip ospf neighbor

clear ip ospf process
y

show ip ospf neighbor
conf t

R3:
int f0/0
ip ospf prio 0
exit

R2:
end
show ip ospf neighbor
conf t

2. OSPF汇总

区域间汇总
-----------------------------------------------------------------
R2:
router ospf 1
area 0 range 22.1.0.0 255.255.0.0
area 0 range 33.1.0.0 255.255.0.0
exit

R1:
end
show ip route ospf
conf t

R4:
int l1
ip add 44.1.2.1 255.255.255.0
exit
int l2
ip add 44.1.3.1 255.255.255.0
exit
router ospf 1
network 44.1.2.0 0.0.0.255 area 2
network 44.1.3.0 0.0.0.255 area 2
exit

R1:
end
show ip route ospf
conf t

R3:
router ospf 1
area 2 range 44.1.0.0 255.255.0.0
exit

区域外汇总
--------------------------------------------------------------------
R4:
int l10
ip add 144.1.1.1 255.255.255.0
exit
int l11
ip add 144.1.2.1 255.255.255.0
exit
int l12
ip add 144.1.3.1 255.255.255.0
exit

router ospf 1
redistribute connected subnets
exit

R1:
end
show ip route ospf
conf t

R4:
router ospf 1
summary-add 144.1.0.0 255.255.0.0
exit

R1:
end
show ip route ospf
conf t

3. OSPF网络类型：
------------------------------------------------------------------------

在点到点的网络OSPF的网络类型
点到点的二层网络类型主要出现的地方有两个：1是串行链路；2是帧中继的点对点链路。

R1:
int s0/0
ip add 12.1.1.1 255.255.255.0
no shut
exit
int l0
ip add 11.1.1.1 255.255.255.0
no shut
exit

router ospf 1
router-id 11.1.1.1
network 12.1.1.0 0.0.0.255 area 0
network 11.1.1.0 0.0.0.255 area 0
exit

R2:
int s0/0
ip add 12.1.1.2 255.255.255.0
no shut
exit
int l0
ip add 22.1.1.1 255.255.255.0
no shut
exit

router ospf 1
router-id 22.1.1.1
network 12.1.1.0 0.0.0.255 area 0
network 22.1.1.0 0.0.0.255 area 0
exit

R1:
end
show ip ospf int s0/0
conf t
-----------------------------------------------------------------
R1/R2:
int s0/0
ip ospf network broadcast
ip ospf network point-to-multipoint
ip ospf network point-to-multipoint non-broadcast
exit

R1:
show ip ospf int s0/0
-------------------------------------------------------------
R1/R2:
int s0/0
ip ospf network non-broadcast
exit

R1:
router ospf 1
neighbor 12.1.1.2
exit

R1:
show ip ospf int s0/0

广播网络的OSPF网络类型
--------------------------------------------------------------------------

R1:
int f0/0
ip add 12.1.1.1 255.255.255.0
no shut
exit
int l0
ip add 11.1.1.1 255.255.255.0
no shut
exit

router ospf 1
router-id 11.1.1.1
network 12.1.1.0 0.0.0.255 area 0
network 11.1.1.0 0.0.0.255 area 0
exit

R2:
int f0/0
ip add 12.1.1.2 255.255.255.0
no shut
exit
int l0
ip add 22.1.1.1 255.255.255.0
no shut
exit

router ospf 1
router-id 22.1.1.1
network 12.1.1.0 0.0.0.255 area 0
network 22.1.1.0 0.0.0.255 area 0
exit

R1:
end
show ip ospf int f0/0
conf t
----------------------------------------------------------------------
R1/R2:
int f0/0
ip ospf network point-to-point
exit

R1:
show ip ospf int f0/0

不同网络类型之间相互学习
----------------------------------------------------------------

R1:
int s0/0
ip add 12.1.1.1 255.255.255.0
no shut
exit
int l0
ip add 11.1.1.1 255.255.255.0
no shut
exit

router ospf 1
router-id 11.1.1.1
network 12.1.1.0 0.0.0.255 area 0
network 11.1.1.0 0.0.0.255 area 0
exit

R2:
int s0/0
ip add 12.1.1.2 255.255.255.0
no shut
exit
int l0
ip add 22.1.1.1 255.255.255.0
no shut
exit

router ospf 1
router-id 22.1.1.1
network 12.1.1.0 0.0.0.255 area 0
network 22.1.1.0 0.0.0.255 area 0
exit

R1:
int s0/0
ip ospf network point-to-point
exit

R2:
int s0/0
ip ospf network broadcast
exit

R1:
show ip ospf neighbor
show ip route
show ip ospf database

NBMA环境下的OSPF
----------------------------------------------------------

R4:
frame-relay switch

int s0/1
encap frame-relay
frame-relay lmi-type cisco
frame-relay intf-type dce
frame-relay route 102 int s0/2 201
frame-relay route 103 int s0/3 301
no shut
exit

int s0/2
encap frame-relay
frame-relay lmi-type cisco
frame-relay intf-type dce
frame-relay route 201 int s0/1 102
no shut
exit

int s0/3
encap frame-relay
frame-relay lmi-type cisco
frame-relay intf-type dce
frame-relay route 301 int s0/1 103
no shut
exit

end
show frame-relay route
conf t

R1:
int s0/0
ip add 123.1.1.1 255.255.255.0
encap frame-relay
no frame-relay inverse-arp
frame-relay map ip 123.1.1.2 102 broadcast
frame-relay map ip 123.1.1.3 103 broadcast
no shut
exit

R2:
int s0/0
ip add 123.1.1.2 255.255.255.0
encap frame-relay
no frame-relay inverse-arp
frame-relay map ip 123.1.1.1 201 broadcast
frame-relay map ip 123.1.1.3 201 broadcast
no shut
exit

R3:
int s0/0
ip add 123.1.1.3 255.255.255.0
encap frame-relay
no frame-relay inverse-arp
frame-relay map ip 123.1.1.1 301 broadcast
frame-relay map ip 123.1.1.2 301 broadcast
no shut
exit

R2:
ping 123.1.1.1
ping 123.1.1.3

R1:
router ospf 1
router-id 11.1.1.1
network 123.1.1.0 0.0.0.255 area 0
network 11.1.1.0 0.0.0.255 area 0
exit

R2:
router ospf 1
router-id 22.1.1.1
network 123.1.1.0 0.0.0.255 area 0
network 22.1.1.0 0.0.0.255 area 0
exit

R3:
router ospf 1
router-id 33.1.1.1
network 123.1.1.0 0.0.0.255 area 0
network 22.1.1.0 0.0.0.255 area 0
exit

R1:
show ip ospf neighbor

会发现并没有任何邻居发现，这是因为在NBMA的网络，是没有办法自动发现邻居的，需要手动指邻居，在任何一方指都行。

R1:
router ospf 1
neighbor 123.1.1.2
neighbor 123.1.1.3
exit

show ip ospf neighbor

R2:
show ip route

会发现邻居已经起来了，但是R2没有学到任何路由，这是因为R3被选为DR，造成DR不对称。在NBMA网络中，一定要控制DR在HUB点上。

R2/R3:
int s0/0
ip ospf priority 0
exit

R2:
show io route ospf
show ip ospf int s0/0

R1/R2/R3:
int s0/0
ip ospf network point-to-multipoint
exit

R1:
show ip route ospf

4. OSPF明文认证和MD5认证：
---------------------------------------------------------------

R1:
int s0/0
ip add 12.1.1.1 255.255.255.0
no shut
exit
int l0
ip add 11.1.1.1 255.255.255.0
no shut
exit

router ospf 1
router-id 11.1.1.1
network 12.1.1.0 0.0.0.255 area 0
network 11.1.1.0 0.0.0.255 area 0
exit

R2:
int s0/0
ip add 12.1.1.2 255.255.255.0
no shut
exit
int l0
ip add 22.1.1.1 255.255.255.0
no shut
exit

router ospf 1
router-id 22.1.1.1
network 12.1.1.0 0.0.0.255 area 0
network 22.1.1.0 0.0.0.255 area 0
exit

R1/R2:
show ip route ospf

R1/R2:
int s0/0
ip ospf authentication
ip ospf authentication-key cisco
exit

R1/R2:
show ip ospf int s0/0

R1/R2:
int s0/0
no ip ospf authentication
no ip ospf authentication-key cisco
exit

router ospf 1
area 0 authentication
no area 0 authentication
exit

OSPF的MD5认证与明文认证的配置非常相似，开启的方法也有两种，基于链路和基于区域。在配置秘钥的时候，都只能去链路下配置。每条链路可以配置成不一样的。

R1/R2:
int s0/0
ip ospf authentication message-digest
ip ospf message-digest-key 1 md5 cisco
exit

R1/R2:
int s0/0
no ip ospf authentication message-digest
no ip ospf message-digest-key 1 md5 cisco
exit

router ospf 1
area 0 authentication message-digest
exit

OSPF链路认证开启优先于区域认证开启，也就是说在链路上开启的明文，但是在区域里开启了MD5，则此链路是明文的认证。

5. OSPF注入默认路由
---------------------------------------------------------------
R2:
router ospf 1
default-information originate always
exit

如果不使用可选的"always"参数, 路由器上必须存在一条默认路由；如果使用该参数，无论路由器上是否存在默认路由，都会向OSPF区域内注入一条默认路由。

6. OSPF特殊区域：
-------------------------------------------------------------------------------

OSPF末节区域