OSPF-LSA系列—LSA TYPE 4和5
2015-04-15 22:56
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通用属性：
类型TYPE、Link ID、ADV Router三者标示了LSA的唯一性
Age存在时间，最大为3600s，正常情况下不会超过1800s，30min周期更新，3600s没有更新会删掉LSA
Seq number范围是80000001-7FFFFFFF
Checksum说明LSA在传输过程有没有出现错误
Age、Seq number和Checksum三者标示了LSA的新旧程度
当多份LSA来到设备时会比较Age、Seq number和Checksum三者来选取一份放入LSDB表中
——————————————————————————————————————————
LSA
作用：1、TYPE 4引导TYPE 5类如何出去
2、告诉TYPE 5类本区域的ABR到达TYPE 5的生成者距离有多远？
通告者：本区域的ABR
传播范围：不在产生TYPE 5类的区域传播，在其他区域引导TYPE 5如何出去
内容：描述本区域ABR到达ASBR距离
——————————————————————————————————————————
R4#show ip ospf database
Summary ASB Link States (Area 10)
Link ID ADV Router Age Seq# Checksum
0.0.0.1 0.0.0.3 4 0x80000001 0x0046A7
——————————————————————————————————————————
R4#show ip ospf database asbr-summary
OSPF Router with ID (0.0.0.4) (Process ID 100)
Summary ASB Link States (Area 10)
Routing Bit Set on this LSA
LS age: 52
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(AS Boundary Router)
Link State ID: 0.0.0.1 (AS Boundary Router address)
Advertising Router: 0.0.0.3
LS Seq Number: 80000001
Checksum: 0x46A7
Length: 28
Network Mask: /0
TOS: 0 Metric: 74
——————————————————————————————————————————
LSA
通告者：产生TYPE 5设备的router-id
传播范围：在整个域中传播，不属于任何区域
内容：路由（网络号、掩码和开销COST）
注意：当导入TYPE 5类路由时，如果导入的路由在导入前已经从OSPF学习到，导入后优先级不如导入前的好，那么TYPE 5类不会产生。
——————————————————————————————————————————
R4#show ip ospf database
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
11.11.11.11 0.0.0.1 97 0x80000001 0x003154 0
——————————————————————————————————————————
R4#show ip ospf database external
OSPF Router with ID (0.0.0.4) (Process ID 100)
Type-5 AS External Link States
Routing Bit Set on this LSA
LS age: 196
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 11.11.11.11 (External Network Number )
Advertising Router: 0.0.0.1
LS Seq Number: 80000001
Checksum: 0x3154
Length: 36
Network Mask: /32
Metric Type: 2 (Larger than any link state path)
TOS: 0
Metric: 2
Forward Address: 0.0.0.0
External Route Tag: 0
——————————————————————————————————————————
LSA
问题：当R6和R4同时存在202.100.1.1/24网段时，R1会不会把R6的放进ospf database中的TYPE 5类LSA中
当R4还没有配置ospf 202.100.1.1/24时，R2把RIP重分布进OSPF
R1#show ip route
O E2 202.100.1.0/24 [110/2] via 12.1.1.2, 00:03:28, FastEthernet0/0
26.0.0.0/24 is subnetted, 1 subnets
O E2 26.1.1.0 [110/2] via 12.1.1.2, 00:05:09, FastEthernet0/0
11.0.0.0/32 is subnetted, 1 subnets
————————————————————————————————————————
R1#show ip ospf database
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
11.11.11.11 0.0.0.1 1275 0x80000001 0x003154 0
26.1.1.0 0.0.0.2 497 0x80000001 0x00BCD7 0
202.100.1.0 0.0.0.2 393 0x80000001 0x001B65 0 R1把R6的202.100.1.1/24网段放进TYPE 5类
————————————————————————————————————————
当R4上配置了202.100.1.1/24网段时，R4优于R2的
R4(config)#int loopback 1
R4(config-if)#ip ospf network point-to-point
R4(config-if)#ip address 202.100.1.1 255.255.255.0
R4(config-if)#ip ospf 100 area 10
R1#show ip route
O IA 202.100.1.0/24 [110/85] via 12.1.1.2, 00:00:41, FastEthernet0/0
26.0.0.0/24 is subnetted, 1 subnets
O E2 26.1.1.0 [110/2] via 12.1.1.2, 00:10:19, FastEthernet0/0
R1#show ip ospf database
Summary Net Link States (Area 5)
Link ID ADV Router Age Seq# Checksum
202.100.1.0 0.0.0.2 872 0x80000001 0x00625D
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
11.11.11.11 0.0.0.1 191 0x80000002 0x002F55 0
26.1.1.0 0.0.0.2 1451 0x80000001 0x00BCD7 0
————————————————————————————————————————
结论：当R6和R4上同时配置了202.100.1.1/24网段时，经过R2比较后，R1是不会把R6的202.100.1.1/24网段放进ospf database的TYPE 5类中
类型TYPE、Link ID、ADV Router三者标示了LSA的唯一性
Age存在时间，最大为3600s，正常情况下不会超过1800s，30min周期更新，3600s没有更新会删掉LSA
Seq number范围是80000001-7FFFFFFF
Checksum说明LSA在传输过程有没有出现错误
Age、Seq number和Checksum三者标示了LSA的新旧程度
当多份LSA来到设备时会比较Age、Seq number和Checksum三者来选取一份放入LSDB表中
——————————————————————————————————————————
LSA
TYPE 4
作用：1、TYPE 4引导TYPE 5类如何出去2、告诉TYPE 5类本区域的ABR到达TYPE 5的生成者距离有多远？
通告者：本区域的ABR
传播范围：不在产生TYPE 5类的区域传播，在其他区域引导TYPE 5如何出去
内容：描述本区域ABR到达ASBR距离
——————————————————————————————————————————
R4#show ip ospf database
Summary ASB Link States (Area 10)
Link ID ADV Router Age Seq# Checksum
0.0.0.1 0.0.0.3 4 0x80000001 0x0046A7
——————————————————————————————————————————
R4#show ip ospf database asbr-summary
OSPF Router with ID (0.0.0.4) (Process ID 100)
Summary ASB Link States (Area 10)
Routing Bit Set on this LSA
LS age: 52
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(AS Boundary Router)
Link State ID: 0.0.0.1 (AS Boundary Router address)
Advertising Router: 0.0.0.3
LS Seq Number: 80000001
Checksum: 0x46A7
Length: 28
Network Mask: /0
TOS: 0 Metric: 74
——————————————————————————————————————————
LSA
TYPE 5
通告者：产生TYPE 5设备的router-id传播范围：在整个域中传播，不属于任何区域
内容：路由（网络号、掩码和开销COST）
注意：当导入TYPE 5类路由时，如果导入的路由在导入前已经从OSPF学习到，导入后优先级不如导入前的好，那么TYPE 5类不会产生。
——————————————————————————————————————————
R4#show ip ospf database
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
11.11.11.11 0.0.0.1 97 0x80000001 0x003154 0
——————————————————————————————————————————
R4#show ip ospf database external
OSPF Router with ID (0.0.0.4) (Process ID 100)
Type-5 AS External Link States
Routing Bit Set on this LSA
LS age: 196
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 11.11.11.11 (External Network Number )
Advertising Router: 0.0.0.1
LS Seq Number: 80000001
Checksum: 0x3154
Length: 36
Network Mask: /32
Metric Type: 2 (Larger than any link state path)
TOS: 0
Metric: 2
Forward Address: 0.0.0.0
External Route Tag: 0
——————————————————————————————————————————
LSA
TYPE 5 扩展实验
问题：当R6和R4同时存在202.100.1.1/24网段时，R1会不会把R6的放进ospf database中的TYPE 5类LSA中
当R4还没有配置ospf 202.100.1.1/24时，R2把RIP重分布进OSPF
R1#show ip route
O E2 202.100.1.0/24 [110/2] via 12.1.1.2, 00:03:28, FastEthernet0/0
26.0.0.0/24 is subnetted, 1 subnets
O E2 26.1.1.0 [110/2] via 12.1.1.2, 00:05:09, FastEthernet0/0
11.0.0.0/32 is subnetted, 1 subnets
————————————————————————————————————————
R1#show ip ospf database
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
11.11.11.11 0.0.0.1 1275 0x80000001 0x003154 0
26.1.1.0 0.0.0.2 497 0x80000001 0x00BCD7 0
202.100.1.0 0.0.0.2 393 0x80000001 0x001B65 0 R1把R6的202.100.1.1/24网段放进TYPE 5类
————————————————————————————————————————
当R4上配置了202.100.1.1/24网段时，R4优于R2的
R4(config)#int loopback 1
R4(config-if)#ip ospf network point-to-point
R4(config-if)#ip address 202.100.1.1 255.255.255.0
R4(config-if)#ip ospf 100 area 10
R1#show ip route
O IA 202.100.1.0/24 [110/85] via 12.1.1.2, 00:00:41, FastEthernet0/0
26.0.0.0/24 is subnetted, 1 subnets
O E2 26.1.1.0 [110/2] via 12.1.1.2, 00:10:19, FastEthernet0/0
R1#show ip ospf database
Summary Net Link States (Area 5)
Link ID ADV Router Age Seq# Checksum
202.100.1.0 0.0.0.2 872 0x80000001 0x00625D
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
11.11.11.11 0.0.0.1 191 0x80000002 0x002F55 0
26.1.1.0 0.0.0.2 1451 0x80000001 0x00BCD7 0
————————————————————————————————————————
结论：当R6和R4上同时配置了202.100.1.1/24网段时，经过R2比较后，R1是不会把R6的202.100.1.1/24网段放进ospf database的TYPE 5类中
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