# 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 count 4.4.4.4 4.4.4.4 1803 0x80000003 0x0044B4 2 5.5.5.5 5.5.5.5 1831 0x80000004 0x00626B 3 IOU5(config)#int s2/0 IOU5(config-if)#shut IOU5(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 detached 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 count 5.5.5.5 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Checksum IOU5(config)#int s2/0 IOU5(config-if)#no shut 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 count 4.4.4.4 4.4.4.4 5 0x80000008 0x003AB9 2 5.5.5.5 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RID Link ID ADV Router Age Seq# Checksum Link count 2.2.2.2 2.2.2.2 956 0x80000008 0x00713B 3 3.3.3.3 3.3.3.3 910 0x80000008 0x00742C 3 4.4.4.4 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RID Link ID ADV Router Age Seq# Checksum 10.1.234.4 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# Checksum 10.1.1.1 2.2.2.2 2591 0x80000004 0x001208 10.1.1.1 3.3.3.3 2563 0x80000004 0x00F322 10.1.5.5 4.4.4.4 593 0x80000005 0x009D35 10.1.45.0 4.4.4.4 593 0x80000005 0x000CA4 10.1.123.0 2.2.2.2 2591 0x80000004 0x00CED2 10.1.123.0 3.3.3.3 2563 0x80000004 0x00B0EC # 3类LSA:域间路由前缀 + 本区域ABR的router_id + MASK + Metrics IOU4#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 s2/1 Serial2/1 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 1/255 IOU4# sh ip ro O 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 1 IOU4(config-router)#auto-cost ? reference-bandwidth Use reference bandwidth method to assign OSPF costIOU4(config-router)#auto-cost re IOU4(config-router)#auto-cost reference-bandwidth ? <1-4294967> The reference bandwidth in terms of Mbits per second IOU4(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 10.1.5.5 Routing 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6477 IOU4(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 bandwidth IOU4(config-if)#bandwidth 100000 IOU4(config-if)#do sh ip ro 10.1.5.5 Routing 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cost IOU4(config-if)#ip ospf cost ? <1-65535> Cost IOU4(config-if)#ip ospf cost 1 IOU4(config-if)#do sh ip ro 10.1.5.5 Routing 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2 IOU4(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 count 2.2.2.2 2.2.2.2 1109 0x80000002 0x00F1E5 1 4.4.4.4 4.4.4.4 1 (DNA) 0x80000002 0x00A6FF 3 5.5.5.5 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 nei Neighbor ID Pri State Dead Time Address Interface 4.4.4.4 0 FULL/ - - 10.1.234.4 OSPF_VL0 4.4.4.4 0 FULL/ - 00:01:48 10.1.234.4 Serial2/0 1.1.1.1 1 FULL/DR 00:00:34 10.1.123.1 Ethernet0/0 2.2.2.2 1 FULL/BDR 00:00:38 10.1.123.2 Ethernet0/0 IOU3#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 10.1.22.22 Routing 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