#LSA的同步更新机制#LSAID：LSA的标识符#ADVRouter：通告LSA的路由器#Age（老化时间，3600s，类似于毒化）：1800s更新，用于删除垃圾的LSA，因为路由器无法删除其他路由
.
# LSA的同步更新机制# LSA ID：LSA的标识符# ADV Router：通告LSA的路由器# Age（老化时间，3600s，类似于毒化）：1800s更新，用于删除垃圾的LSA，因为路由器无法删除其他路由的LSA# Seq（序列号）：LSA的新旧程度，序列号越大，同步；# Checksum（校验码）：除了LSA老化时间的校验和，校验和越大，同步；# 以上均相同则计算老化时间之差，超过15min，900s则同步；# 关闭互联端口后，LSA并不直接删除，LSA_age逐渐增加至3600后删除IOU5#sh ip ospf database OSPF Router with ID (5.5.5.5) (Process ID 1) Router Link States (Area 1)Link ID ADV Router Age Seq# Checksum Link count4.4.4.4 4.4.4.4 1803 0x80000003 0x0044B4 25.5.5.5 5.5.5.5 1831 0x80000004 0x00626B 3IOU5(config)#int s2/0IOU5(config-if)#shutIOU5(config-if)#*Nov 20 14:25:17.364: %OSPF-5-ADJCHG: Process 1, Nbr 4.4.4.4 on Serial2/0 from FULL to DOWN, Neighbor Down: Interface down or detachedIOU5#sh ip ospf database OSPF Router with ID (5.5.5.5) (Process ID 1) Router Link States (Area 1)Link ID ADV Router Age Seq# Checksum Link count5.5.5.5 5.5.5.5 202 0x80000007 0x001FCF 1#开启互联端口后，LSA_seq较大的同步较小的LSA；并计算ChecksumIOU5(config)#int s2/0 IOU5(config-if)#no shutIOU5#sh ip ospf database OSPF Router with ID (5.5.5.5) (Process ID 1) Router Link States (Area 1)Link ID ADV Router Age Seq# Checksum Link count4.4.4.4 4.4.4.4 5 0x80000008 0x003AB9 25.5.5.5 5.5.5.5 4 0x80000008 0x005A6F 3
# 1、1类LSA（P2P网络） IOU4#sh ip ospf database OSPF Router with ID (4.4.4.4) (Process ID 1) Router Link States (Area 0) #始发RID #始发RIDLink ID ADV Router Age Seq# Checksum Link count2.2.2.2 2.2.2.2 956 0x80000008 0x00713B 33.3.3.3 3.3.3.3 910 0x80000008 0x00742C 34.4.4.4 4.4.4.4 918 0x80000009 0x00FBB6 2# 4种链路类型# a. Stub Network：前缀 + Mask + Metrics Link connected to: a Stub Network (Link ID) Network/subnet number: 10.1.5.5 (Link Data) Network Mask: 255.255.255.255 Number of MTID metrics: 0 TOS 0 Metrics: 1 # b. point-to-point：对端Router-ID + 本端互联接口地址（ + Metrics Link connected to: another Router (point-to-point) (Link ID) Neighboring Router ID: 4.4.4.4 (Link Data) Router Interface address: 10.1.45.5 Number of MTID metrics: 0 TOS 0 Metrics: 64 # c. Transit Network：DR的接口IP（伪节点）+ Metrics Link connected to: a Transit Network (Link ID) Designated Router address: 10.1.234.4 (Link Data) Router Interface address: 10.1.234.4 Number of MTID metrics: 0 TOS 0 Metrics: 64# d. Virtual Link ： 对端Router-id + 本端互联接口地址（计算得出） + Metrics Link connected to: a Virtual Link (Link ID) Neighboring Router ID: 4.4.4.4 (Link Data) Router Interface address: 10.1.234.2 Number of MTID metrics: 0 TOS 0 Metrics: 64 # 2、2类LSA（MA网络的DR）IOU4#sh ip ospf database Net Link States (Area 0)#DR接口IP #DR的RIDLink ID ADV Router Age Seq# Checksum10.1.234.4 4.4.4.4 886 0x80000002 0x0012F4# 2类LSA： DR网段MASK + LAN节点IOU4#sh ip ospf database network OSPF Router with ID (4.4.4.4) (Process ID 1) Net Link States (Area 0) Routing Bit Set on this LSA in topology Base with MTID 0 LS age: 811 Options: (No TOS-capability, DC) LS Type: Network Links Link State ID: 10.1.234.4 (address of Designated Router) Advertising Router: 4.4.4.4 LS Seq Number: 80000002 Checksum: 0x12F4 Length: 36 Network Mask: /24 # MA网络中，如果LAN中接口mask不一致，无法建立邻居 Attached Router: 4.4.4.4 Attached Router: 2.2.2.2 Attached Router: 3.3.3.3 # 3、3类LSA （ABR产生的域间路由）IOU4#sh ip ospf database Summary Net Link States (Area 0)Link ID ADV Router Age Seq# Checksum10.1.1.1 2.2.2.2 2591 0x80000004 0x00120810.1.1.1 3.3.3.3 2563 0x80000004 0x00F32210.1.5.5 4.4.4.4 593 0x80000005 0x009D3510.1.45.0 4.4.4.4 593 0x80000005 0x000CA410.1.123.0 2.2.2.2 2591 0x80000004 0x00CED210.1.123.0 3.3.3.3 2563 0x80000004 0x00B0EC# 3类LSA：域间路由前缀 + 本区域ABR的router_id + MASK + MetricsIOU4#sh ip ospf database summary 10.1.5.5 OSPF Router with ID (4.4.4.4) (Process ID 1) Summary Net Link States (Area 0) LS age: 586 Options: (No TOS-capability, DC, Upward) LS Type: Summary Links(Network) Link State ID: 10.1.5.5 (summary Network Number) Advertising Router: 4.4.4.4 LS Seq Number: 80000005 Checksum: 0x9D35 Length: 28 Network Mask: /32 MTID: 0 Metric: 65 # 3类LSA注意事项： # 1、ABR把非骨干区域的域内路由T1/T2向骨干区域发送T3； 域间路由OIA = T3+T1/T2# 2、ABR把骨干区域的域间路由T3向非骨干区域发送T3；前提，没有对应的域内路由# 3、ABR把骨干区域的域内路由T1/T2向非骨干区域发送T3；# 4、ABR不会把非骨干区域的T3向骨干区域发送T3；# 5、因为ABR只计算来自骨干区域内的T3，不计算非骨干区域的T3
# cost的计算 ：路由方向的入向接口，路由方向和数据方向相反；# 计算公式cost = 10^8/BW(bps)IOU4#sh int s2/1Serial2/1 is up, line protocol is up Hardware is M4T Internet address is 10.1.45.4/24 MTU 1500 bytes, BW 1544 Kbit/sec, DLY 20000 usec, # BW 1544 Kbit/sec 即 1544000 bps reliability 255/255, txload 1/255, rxload 1/255IOU4# sh ip roO 10.1.5.5/32 [110/65] via 10.1.45.5, 00:00:20, Serial2/1 # [110/65] ： cost为65，根据公式： 10^8 / 1544000 = 64.7# 修改cost值# 1、修改cost参考值10^8，建议高于最大带宽值；IOU4(config)#router ospf 1IOU4(config-router)#auto-cost ? reference-bandwidth Use reference bandwidth method to assign OSPF cost <cr>IOU4(config-router)#auto-cost reIOU4(config-router)#auto-cost reference-bandwidth ? <1-4294967> The reference bandwidth in terms of Mbits per secondIOU4(config-router)#auto-cost reference-bandwidth 10000% OSPF: Reference bandwidth is changed. Please ensure reference bandwidth is consistent across all routers.IOU4(config-router)#do sh ip ro% Ambiguous command: "do sh ip ro"IOU4(config-router)#do sh ip ro 10.1.5.5Routing entry for 10.1.5.5/32 Known via "ospf 1", distance 110, metric 6477, type intra area Last update from 10.1.45.5 on Serial2/1, 00:00:19 ago Routing Descriptor Blocks: * 10.1.45.5, from 5.5.5.5, 00:00:19 ago, via Serial2/1 Route metric is 6477, traffic share count is 1 # 修改后，cost值为6477IOU4(config-router)## 2、修改接口带宽IOU4(config-if)#bandwidth ? <1-10000000> Bandwidth in kilobits inherit Specify how bandwidth is inherited qos-reference Reference bandwidth for QOS test receive Specify receive-side bandwidthIOU4(config-if)#bandwidth 100000IOU4(config-if)#do sh ip ro 10.1.5.5Routing entry for 10.1.5.5/32 Known via "ospf 1", distance 110, metric 101, type intra area Last update from 10.1.45.5 on Serial2/1, 00:00:22 ago Routing Descriptor Blocks: * 10.1.45.5, from 5.5.5.5, 00:00:22 ago, via Serial2/1 Route metric is 101, traffic share count is 1 # 修改后，cost值为101 # 3、直接修改costIOU4(config-if)#ip ospf cost ? <1-65535> CostIOU4(config-if)#ip ospf cost 1 IOU4(config-if)#do sh ip ro 10.1.5.5Routing entry for 10.1.5.5/32 Known via "ospf 1", distance 110, metric 2, type intra area Last update from 10.1.45.5 on Serial2/1, 00:00:00 ago Routing Descriptor Blocks: * 10.1.45.5, from 5.5.5.5, 00:00:00 ago, via Serial2/1 Route metric is 2, traffic share count is 1 # 修改后，cost值为2IOU4(config-if)#
# virtual-links不发送Hello包，Hello包抑制IOU2#sh ip ospf virtual-links Virtual Link OSPF_VL1 to router 4.4.4.4 is up Run as demand circuit DoNotAge LSA allowed. # (DoNotAge,age不更新，简称DNA) Transit area 1, via interface Serial2/0 Topology-MTID Cost Disabled Shutdown Topology Name 0 64 no no Base Transmit Delay is 1 sec, State POINT_TO_POINT, Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 Hello due in 00:00:01 Adjacency State FULL (Hello suppressed) # Hello包抑制，virtual-links不发送Hello包 Index 1/4, retransmission queue length 0, number of retransmission 0 First 0x0(0)/0x0(0) Next 0x0(0)/0x0(0) Last retransmission scan length is 0, maximum is 0 Last retransmission scan time is 0 msec, maximum is 0 msec# DNA：do not age，老化时间age不更新IOU2#sh ip ospf data OSPF Router with ID (2.2.2.2) (Process ID 1) Router Link States (Area 0)Link ID ADV Router Age Seq# Checksum Link count2.2.2.2 2.2.2.2 1109 0x80000002 0x00F1E5 14.4.4.4 4.4.4.4 1 (DNA) 0x80000002 0x00A6FF 35.5.5.5 5.5.5.5 289 (DNA) 0x80000004 0x00626B 3# virtual-links问题：产生次优路径或者环路IOU3# sh ip ospf neiNeighbor ID Pri State Dead Time Address Interface4.4.4.4 0 FULL/ - - 10.1.234.4 OSPF_VL04.4.4.4 0 FULL/ - 00:01:48 10.1.234.4 Serial2/01.1.1.1 1 FULL/DR 00:00:34 10.1.123.1 Ethernet0/02.2.2.2 1 FULL/BDR 00:00:38 10.1.123.2 Ethernet0/0IOU3#sh ip ospf da summ 10.1.22.22 OSPF Router with ID (3.3.3.3) (Process ID 1) Summary Net Link States (Area 0) Routing Bit Set on this LSA in topology Base with MTID 0 LS age: 2 (DoNotAge) Options: (No TOS-capability, DC, Upward) LS Type: Summary Links(Network) Link State ID: 10.1.22.22 (summary Network Number) Advertising Router: 2.2.2.2 LS Seq Number: 80000001 Checksum: 0xF804 Length: 28 Network Mask: /32 MTID: 0 Metric: 1 Summary Net Link States (Area 1) LS age: 1826 Options: (No TOS-capability, DC, Upward) LS Type: Summary Links(Network) Link State ID: 10.1.22.22 (summary Network Number) Advertising Router: 2.2.2.2 LS Seq Number: 80000001 Checksum: 0xF804 Length: 28 Network Mask: /32 MTID: 0 Metric: 1 Summary Net Link States (Area 2) LS age: 1825 Options: (No TOS-capability, DC, Upward) LS Type: Summary Links(Network) Link State ID: 10.1.22.22 (summary Network Number) Advertising Router: 2.2.2.2 LS Seq Number: 80000001 Checksum: 0xF804 Length: 28 Network Mask: /32 MTID: 0 Metric: 1 LS age: 562 Options: (No TOS-capability, DC, Upward) LS Type: Summary Links(Network) Link State ID: 10.1.22.22 (summary Network Number) Advertising Router: 3.3.3.3 LS Seq Number: 80000001 Checksum: 0xDF98 Length: 28 Network Mask: /32 MTID: 0 Metric: 129 # 产生次优路径原因：virtual-links修改路由器状态为ABR，ABR只计算来自a0的T3；IOU3#sh ip ro 10.1.22.22Routing entry for 10.1.22.22/32 Known via "ospf 1", distance 110, metric 129, type inter area Last update from 10.1.234.4 on Serial2/0, 00:38:33 ago Routing Descriptor Blocks: * 10.1.234.4, from 2.2.2.2, 00:38:33 ago, via Serial2/0 Route metric is 129, traffic share count is 1
