单区域OSPF(p2p)
OSPF作为一种内部网关协议(InteriorGatewayProtocol,IGP),用于在同一个自治系统(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将网络划分为四种类型:广播多路访问型(BMA)、
非广播多路访问型(NBMA)、
点到点型(Point-to-Point)、
点到多点型(Point-to-MultiPoint)。
不同的二层链路的类型需要OSPF不同的网络类型来适应。
下面的几个术语是学习OSPF要掌握的:
1.链路:链路就是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与邻居路由器的关系。所有链路状态信息构成链路状态数据库;
1.区域:有相同的区域标志的一组路由器和网络的集合。在同一个区域内的路由器有相同的链路状态数据库;
2.自治系统:采用同一种路由协议交换路由信息的路由器及其网络构成一个自治系统;
3.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;
4.最短路经优先(SPF)算法:是OSPF路由协议的基础。SPF算法有时也被称为Dijkstra算法,这是因为最短路径优先算法(SPF)是Dijkstra发明的。OSPF路由器利用SPF,独立地计算出到达任意目的地的最佳路由。
点到点链路上的OSPF
R1:
R1(config)#intlo0
R1(config-if)#ipadd1.1.1.1255.255.255.0、
R1(config)#ints0/0
R1(config-if)#ipadd12.1.1.1255.255.255.0
R1(config-if)#nosh
R1(config)#routeros110
R1(config-router)#router-id1.1.1.1
R1(config-router)#network1.1.1.00.0.0.255area0
R1(config-router)#network12.1.1.00.0.0.255area0
R2:
R2(config)#ints0/0
R2(config-if)#ipadd13.1.1.1255.255.255.0
R3(config-if)#nosh
R2(config)#intlo0
R2(config-if)#ipadd2.2.2.2255.255.255.0
R2(config-if)#ints0/1
R2(config-if)#ipadd12.1.1.2255.255.255.0
R3(config-if)#nosh
R2(config)#routeros110
R2(config-router)#router-id2.2.2.2
R2(config-router)#network12.1.1.00.0.0.255area0
R2(config-router)#network2.2.2.00.0.0.255area0
R2(config-router)#network13.1.1.00.0.0.255area0
R3:
R3(config)#ints0/1
R3(config-if)#ipadd13.1.1.2255.255.255.0
R3(config)#nosh
R3(config)#intlo0
R3(config-if)#ipadd3.3.3.3255.255.255.0
R3(config)#routeros110
R3(config-router)#router-id3.3.3.3
R3(config-router)#network3.3.3.00.0.0.255area0
R3(config-router)#network13.1.1.00.0.0.255area0
R1:查看路由表信息
R1#shipro
Codes:C-connected,S-static,R-RIP,M-mobile,B-BGP
D-EIGRP,EX-EIGRPexternal,O-OSPF,IA-OSPFinterarea
N1-OSPFNSSAexternaltype1,N2-OSPFNSSAexternaltype2
E1-OSPFexternaltype1,E2-OSPFexternaltype2
i-IS-IS,su-IS-ISsummary,L1-IS-ISlevel-1,L2-IS-ISlevel-2
ia-IS-ISinterarea,*-candidatedefault,U-per-userstaticroute
o-ODR,P-periodicdownloadedstaticroute
Gatewayoflastresortisnotset
1.0.0.0/24issubnetted,1subnets
C1.1.1.0isdirectlyconnected,Loopback0
2.0.0.0/32issubnetted,1subnets
O2.2.2.2[110/65]via12.1.1.2,00:06:17,Serial0/0
3.0.0.0/32issubnetted,1subnets
O3.3.3.3[110/129]via12.1.1.2,00:06:17,Serial0/0
12.0.0.0/24issubnetted,1subnets
C12.1.1.0isdirectlyconnected,Serial0/0
13.0.0.0/24issubnetted,1subnets
O13.1.1.0[110/128]via12.1.1.2,00:06:17,Serial0/0
注意:R1学习到R2/R3lo0口的路由信息是个32位的路由,这里可以通过在lo0接口上改网络类型,还原实际路由信息。
R2:
R2(config)#intlo0
R2(config-if)#ipospfnetworkpoint-to-point
R3:
R3(config)#intlo0
R3(config-if)#ipospfnetworkpoint-to-point
在R2/R3上lo0改完网络类型,在去R1上看就是24位的路由了。
R1:
R1#shipro
Codes:C-connected,S-static,R-RIP,M-mobile,B-BGP
D-EIGRP,EX-EIGRPexternal,O-OSPF,IA-OSPFinterarea
N1-OSPFNSSAexternaltype1,N2-OSPFNSSAexternaltype2
E1-OSPFexternaltype1,E2-OSPFexternaltype2
i-IS-IS,su-IS-ISsummary,L1-IS-ISlevel-1,L2-IS-ISlevel-2
ia-IS-ISinterarea,*-candidatedefault,U-per-userstaticroute
o-ODR,P-periodicdownloadedstaticroute
Gatewayoflastresortisnotset
1.0.0.0/24issubnetted,1subnets
C1.1.1.0isdirectlyconnected,Loopback0
2.0.0.0/24issubnetted,1subnets
O2.2.2.0[110/65]via12.1.1.2,00:00:10,Serial0/0
3.0.0.0/24issubnetted,1subnets
O3.3.3.0[110/129]via12.1.1.2,00:00:10,Serial0/0
12.0.0.0/24issubnetted,1subnets
C12.1.1.0isdirectlyconnected,Serial0/0
13.0.0.0/24issubnetted,1subnets
O13.1.1.0[110/128]via12.1.1.2,00:00:10,Serial0/0
R1:查看邻居表信息
R1#shiposnei
NeighborIDPriStateDeadTimeAddressInterface
2.2.2.20FULL/-00:00:3812.1.1.2Serial0/0
NeighborID
2.2.2.2邻居router-id号。
State
FULL/-经历五个状态,达到FULL状态,并且不线DR(p2p网络)
DeadTime
00:00:38老化时间到计时
Interface
Serial0/0本地与邻居相连接口。
R1#shiposints0/0
Serial0/0isup,lineprotocolisup
InternetAddress12.1.1.1/24,Area0
ProcessID110,RouterID1.1.1.1,NetworkTypePOINT_TO_POINT,Cost:64(cost值)
TransmitDelayis1sec,StatePOINT_TO_POINT,(网络类型p2p)
Timerintervalsconfigured,Hello10,Dead40,Wait40,Retransmit5
Hello更新时间10s老化时间是hello时间4倍wait时间也是hello时间4倍(选DR等待时间)
oob-resynctimeout40
Helloduein00:00:07
SupportsLink-localSignaling(LLS)
Index2/2,floodqueuelength0
Next0x0(0)/0x0(0)
Lastfloodscanlengthis1,maximumis1
Lastfloodscantimeis0msec,maximumis0msec
NeighborCountis1,Adjacentneighborcountis1
Adjacentwithneighbor2.2.2.2
Suppresshellofor0neighbor(s)
Ospfcost计算:ospfcost=10^8/接口带宽(bit)
列如:
R1#shints0/0
Serial0/0isup,lineprotocolisup
HardwareisM4T
Internetaddressis12.1.1.1/24
MTU1500bytes,BW1544Kbit,DLY20000usec,
reliability255/255,txload1/255,rxload1/255
EncapsulationHDLC,crc16,loopbacknotset
S0/0cost值=100000000/1544000=64(取整数)
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R1:ospflsdb信息
R1#shiposda
OSPFRouterwithID(1.1.1.1)(ProcessID110)
RouterLinkStates(Area0)注:lsa1类(router)
LinkIDADVRouterAgeSeq#ChecksumLinkcount
1.1.1.11.1.1.118230x800000030x00342C3
2.2.2.22.2.2.28090x800000040x0066285
3.3.3.33.3.3.37940x800000050x0041053
注:
lsa1类中:
linkidadvrouter所表示的是一致router―id信息。
在R2上看:
R2#shiposda
OSPFRouterwithID(2.2.2.2)(ProcessID110)
RouterLinkStates(Area0)
LinkIDADVRouterAgeSeq#ChecksumLinkcount
1.1.1.11.1.1.116810x800000040x00322D3
2.2.2.22.2.2.26170x800000050x0064295
3.3.3.33.3.3.35630x800000060x003F063
注:说明在同一个区域里面,每台路由的router(lsa1)信息是一致的。
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R1:通过ospf学习到的路由信息
R1#shiproos
2.0.0.0/24issubnetted,1subnets
O2.2.2.0[110/65]via12.1.1.2,00:16:06,Serial0/0
3.0.0.0/24issubnetted,1subnets
O3.3.3.0[110/129]via12.1.1.2,00:16:06,Serial0/0
13.0.0.0/24issubnetted,1subnets
O13.1.1.0[110/128]via12.1.1.2,00:16:06,Serial0/0
注:通过lsa1类学习到的路由前缀都是打o的。
R1查看lsa1(router)数据库信息:
R1#shiposdatabaserouter
OSPFRouterwithID(1.1.1.1)(ProcessID110)
RouterLinkStates(Area0)
LSage:1193
Options:(NoTOS-capability,DC)
LSType:RouterLinks
LinkStateID:1.1.1.1
AdvertisingRouter:1.1.1.1
LSSeqNumber:80000004
Checksum:0x322D
Length:60
NumberofLinks:3
Linkconnectedto:anotherRouter(point-to-point)
(LinkID)NeighboringRouterID:2.2.2.2
(LinkData)RouterInterfaceaddress:12.1.1.1(拓扑信息)
NumberofTOSmetrics:0
TOS0Metrics:64
Linkconnectedto:aStubNetwork
(LinkID)Network/subnetnumber:12.1.1.0
(LinkData)NetworkMask:255.255.255.0
NumberofTOSmetrics:0
TOS0Metrics:64
Linkconnectedto:aStubNetwork
(LinkID)Network/subnetnumber:1.1.1.1
(LinkData)NetworkMask:255.255.255.255(路由信息)
NumberofTOSmetrics:0
TOS0Metrics:1
LSage:199
Options:(NoTOS-capability,DC)
LSType:RouterLinks
LinkStateID:2.2.2.2
AdvertisingRouter:2.2.2.2
LSSeqNumber:80000005
Checksum:0x6429
Length:84
NumberofLinks:5
Linkconnectedto:anotherRouter(point-to-point)
(LinkID)NeighboringRouterID:3.3.3.3
(LinkData)RouterInterfaceaddress:13.1.1.1
NumberofTOSmetrics:0
TOS0Metrics:64
Linkconnectedto:aStubNetwork
(LinkID)Network/subnetnumber:13.1.1.0
(LinkData)NetworkMask:255.255.255.0
NumberofTOSmetrics:0
TOS0Metrics:64
Linkconnectedto:aStubNetwork
(LinkID)Network/subnetnumber:2.2.2.0
(LinkData)NetworkMask:255.255.255.0
NumberofTOSmetrics:0
TOS0Metrics:1
Linkconnectedto:anotherRouter(point-to-point)
(LinkID)NeighboringRouterID:1.1.1.1
(LinkData)RouterInterfaceaddress:12.1.1.2
NumberofTOSmetrics:0
TOS0Metrics:64
Linkconnectedto:aStubNetwork
(LinkID)Network/subnetnumber:12.1.1.0
(LinkData)NetworkMask:255.255.255.0
NumberofTOSmetrics:0
TOS0Metrics:64
LSage:147
Options:(NoTOS-capability,DC)
LSType:RouterLinks
LinkStateID:3.3.3.3
AdvertisingRouter:3.3.3.3
LSSeqNumber:80000006
Checksum:0x3F06
Length:60
NumberofLinks:3
Linkconnectedto:aStubNetwork
(LinkID)Network/subnetnumber:3.3.3.0
(LinkData)NetworkMask:255.255.255.0
NumberofTOSmetrics:0
TOS0Metrics:1
Linkconnectedto:anotherRouter(point-to-point)
(LinkID)NeighboringRouterID:2.2.2.2
(LinkData)RouterInterfaceaddress:13.1.1.2
NumberofTOSmetrics:0
TOS0Metrics:64
Linkconnectedto:aStubNetwork
(LinkID)Network/subnetnumber:13.1.1.0
(LinkData)NetworkMask:255.255.255.0
NumberofTOSmetrics:0
TOS0Metrics:64