本文說明開放最短路徑優先(OSPF)如何將第7類非純末梢區域(NSSA)鏈路狀態通告(LSA)轉換為第5類LSA。
本文件沒有特定需求。
本文件所述內容不限於特定軟體和硬體版本。
如需文件慣例的詳細資訊,請參閱思科技術提示慣例。
本節提供用於設定本文件中所述功能的資訊。
注意:要查詢有關本文檔中使用的命令的其他資訊,請使用命令查詢工具(僅限註冊客戶)。
本檔案會使用下圖中所示的網路設定。
本文檔使用此處顯示的配置。
路由器1.1.1.1 |
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Current configuration: hostname r1.1.1.1 interface Loopback0 ip address 1.1.1.1 255.0.0.0 interface Serial2/1/0 ip address 5.0.0.1 255.0.0.0 interface Ethernet2/0/0 ip address 4.0.0.1 255.0.0.0 router ospf 4 redistribute static metric 5 metric-type 1 network 5.0.0.0 0.255.255.255 area 1 network 4.0.0.0 0.255.255.255 area 1 area 1 nssa ip route 9.0.0.0 255.0.0.0 4.0.0.2 end |
路由器2.2.2.2 |
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Current configuration: hostname r2.2.2.2 interface Loopback0 ip address 2.2.2.2 255.0.0.0 interface Serial0/1/0 ip address 5.0.0.2 255.0.0.0 interface ATM1/0.20 ip address 6.0.0.2 255.0.0.0 router ospf 2 network 5.0.0.0 0.255.255.255 area 1 network 6.0.0.0 0.255.255.255 area 0 area 1 nssa end |
路由器3.3.3.3 |
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Current configuration: hostname r3.3.3.3 interface Loopback0 ip address 3.3.3.3 255.0.0.0 interface ATM2/0.20 point-to-point ip address 6.0.0.3 255.0.0.0 router ospf 2 network 6.0.0.0 0.255.255.255 area 0 end |
本節提供的資訊可用於確認您的組態是否正常運作。
輸出直譯器工具(僅供註冊客戶使用)支援某些show命令,此工具可讓您檢視show命令輸出的分析。
show ip ospf database — 顯示LSA清單並將其鍵入鏈路狀態資料庫。此清單僅顯示LSA報頭中的資訊。
show ip ospf database nssa-external — 僅顯示有關NSSA外部LSA的資訊。
show ip ospf database external — 僅顯示關於外部LSA的資訊。
show ip ospf database [router] [link-state-id] — 顯示資料庫中路由器的所有LSA的清單。LSA由每台路由器生成,這些基本LSA列出所有路由器的鏈路或介面,以及鏈路的狀態和傳出成本。它們只被淹沒在它們的源頭地區。
show ip ospf database summary <link-state id> — 顯示區域邊界路由器(ABR)摘要鏈路。
show ip route — 顯示路由表的當前狀態。
要檢視給定此網路環境的OSPF資料庫外觀,請使用show ip ospf database命令。
r2.2.2.2#show ip ospf database OSPF Router with ID (2.2.2.2) (Process ID 2) Router Link States (Area 0) Link ID ADV Router Age Seq# Checksum Link count 2.2.2.2 2.2.2.2 1235 0x8000001D 0xD9FF 2 3.3.3.3 3.3.3.3 1100 0x8000000B 0x9455 2 Summary Net Link States (Area 0) Link ID ADV Router Age Seq# Checksum 4.0.0.0 2.2.2.2 1979 0x80000002 0xFDE7 5.0.0.0 2.2.2.2 1483 0x80000004 0x8864 Router Link States (Area 1) Link ID ADV Router Age Seq# Checksum Link count 1.1.1.1 1.1.1.1 319 0x8000000C 0xAFA8 3 2.2.2.2 2.2.2.2 220 0x8000002F 0xD478 2 Summary Net Link States (Area 1) Link ID ADV Router Age Seq# Checksum 6.0.0.0 2.2.2.2 1483 0x8000001C 0x7894 Type-7 AS External Link States (Area 1) Link ID ADV Router Age Seq# Checksum Tag 9.0.0.0 1.1.1.1 334 0x80000005 0xD738 0 Type-5 AS External Link States Link ID ADV Router Age Seq# Checksum Tag 9.0.0.0 2.2.2.2 1725 0x80000004 0x50C6 0
要將外部路由通告到NSSA,自治系統邊界路由器(ASBR)會建立nssa外部LSA(型別7)。
r2.2.2.2#show ip ospf database nssa-external 9.0.0.0 OSPF Router with ID (2.2.2.2) (Process ID 2) Type-7 AS External Link States (Area 1) Routing Bit Set on this LSA LS age: 381 Options: (No TOS-capability, Type 7/5 translation, DC) !--- This can be translated into a type 5 LSA by !--- an ABR. LS Type: AS External Link Link State ID: 9.0.0.0 (External Network Number ) !--- The ASBR (Router 1.1.1.1) advertises !--- 9.0.0.0/8. Advertising Router: 1.1.1.1 !--- Router ID of the ASBR. LS Seq Number: 80000005 Checksum: 0xD738 Length: 36 Network Mask: /8 Metric Type: 1 (Comparable directly to link state metric) TOS: 0 Metric: 5 Forward Address: 4.0.0.1 !--- Forwarding address is incorrectly specified !--- as an interface on the ASBR.
ABR將第7類LSA轉換為第5類LSA,並將第5類LSA傳播到正常區域。
r2.2.2.2#show ip ospf database external 9.0.0.0 OSPF Router with ID (2.2.2.2) (Process ID 2) Type-5 AS External Link States LS age: 1782 Options: (No TOS-capability, DC) LS Type: AS External Link Link State ID: 9.0.0.0 (External Network Number ) !--- Router 2.2.2.2 advertises 9.0.0.0/8. Advertising Router: 2.2.2.2 !--- When the conversion is complete, the advertising !--- router ID becomes the ABR router ID !--- because the ABR originates this type 5 LSA. LS Seq Number: 80000004 Checksum: 0x50C6 Length: 36 Network Mask: /8 Metric Type: 1 (Comparable directly to link state metric) TOS: 0 Metric: 5 Forward Address: 4.0.0.1 External Route Tag: 0 r2.2.2.2#show ip ospf database router 1.1.1.1 OSPF Router with ID (2.2.2.2) (Process ID 2) Router Link States (Area 1) Routing Bit Set on this LSA LS age: 426 Options: (No TOS-capability, DC) LS Type: Router Links Link State ID: 1.1.1.1 !--- For router links, Link State ID is always the same !--- as the advertising router (next line). Advertising Router: 1.1.1.1 LS Seq Number: 8000000C Checksum: 0xAFA8 Length: 60 AS Boundary Router !--- Bit E in the router LSA indicates that this router !--- originates from external LSAs. Number of Links: 3 !--- There are three links in area 1. Link connected to: a Stub Network !--- This represents the Ethernet segment 4.0.0.0/8. (Link ID) Network/subnet number: 4.0.0.0 (Link Data) Network Mask: 255.0.0.0 Number of TOS metrics: 0 TOS 0 Metrics: 10 !--- The OSPF cost of the Ethernet segment. Link connected to: another Router (point-to-point) !--- Shows that Router 1.1.1.1 is a neighbor with !--- Router 2.2.2.2. (Link ID) Neighboring Router ID: 2.2.2.2 (Link Data) Router Interface address: 5.0.0.1 !--- The interface address that connects to Router !--- 2.2.2.2 is 5.0.0.1. Number of TOS metrics: 0 TOS 0 Metrics: 64 !--- The OSPF cost of the link that connects !--- the two routers. Link connected to: a Stub Network !--- This represents the serial link 5.0.0.0/8. (Link ID) Network/subnet number: 5.0.0.0 (Link Data) Network Mask: 255.0.0.0 Number of TOS metrics: 0 TOS 0 Metrics: 64 !--- The OSPF cost of the serial link.
從這裡的bold輸出可以看到,儘管Router 2.2.2.2的組態中沒有任何redistribute陳述式,但它仍是ASBR,因為它將第7類LSA轉換為第5類LSA。
r2.2.2.2#show ip ospf database router 2.2.2.2 OSPF Router with ID (2.2.2.2) (Process ID 2) Router Link States (Area 0) LS age: 1361 Options: (No TOS-capability, DC) LS Type: Router Links Link State ID: 2.2.2.2 Advertising Router: 2.2.2.2 LS Seq Number: 8000001D Checksum: 0xD9FF Length: 48 Area Border Router !--- Bit B is set in the router LSA to indicate !--- that this router is an ABR. AS Boundary Router !--- Bit E in the router LSA indicates that this router !--- originates from external LSAs. Number of Links: 2 !--- There are two links in area 0. Link connected to: another Router (point-to-point) (Link ID) Neighboring Router ID: 3.3.3.3 (Link Data) Router Interface address: 6.0.0.2 Number of TOS metrics: 0 TOS 0 Metrics: 1 Link connected to: a Stub Network (Link ID) Network/subnet number: 6.0.0.0 (Link Data) Network Mask: 255.0.0.0 Number of TOS metrics: 0 TOS 0 Metrics: 1 Router Link States (Area 1) LS age: 346 Options: (No TOS-capability, DC) LS Type: Router Links Link State ID: 2.2.2.2 Advertising Router: 2.2.2.2 LS Seq Number: 8000002F Checksum: 0xD478 Length: 48 Area Border Router AS Boundary Router Number of Links: 2 Link connected to: another Router (point-to-point) (Link ID) Neighboring Router ID: 1.1.1.1 (Link Data) Router Interface address: 5.0.0.2 Number of TOS metrics: 0 TOS 0 Metrics: 64 Link connected to: a Stub Network (Link ID) Network/subnet number: 5.0.0.0 (Link Data) Network Mask: 255.0.0.0 Number of TOS metrics: 0 TOS 0 Metrics: 64 r2.2.2.2#show ip ospf database router 3.3.3.3 OSPF Router with ID (2.2.2.2) (Process ID 2) Router Link States (Area 0) LS age: 1245 Options: (No TOS-capability, DC) LS Type: Router Links Link State ID: 3.3.3.3 Advertising Router: 3.3.3.3 LS Seq Number: 8000000B Checksum: 0x9455 Length: 48 Number of Links: 2 Link connected to: another Router (point-to-point) (Link ID) Neighboring Router ID: 2.2.2.2 (Link Data) Router Interface address: 6.0.0.3 Number of TOS metrics: 0 TOS 0 Metrics: 1 Link connected to: a Stub Network (Link ID) Network/subnet number: 6.0.0.0 (Link Data) Network Mask: 255.0.0.0 Number of TOS metrics: 0 TOS 0 Metrics: 1
要將路由從一個區域通告到另一個區域,ABR會建立彙總LSA(型別3)。
r2.2.2.2#show ip ospf database summary 4.0.0.0 OSPF Router with ID (2.2.2.2) (Process ID 2) Summary Net Link States (Area 0) LS age: 172 Options: (No TOS-capability, DC) LS Type: Summary Links(Network) Link State ID: 4.0.0.0 (summary Network Number) !--- The ABR (Router 2.2.2.2) advertises !--- 4.0.0.0/8 into area 0. Advertising Router: 2.2.2.2 LS Seq Number: 80000003 Checksum: 0xFBE8 Length: 28 Network Mask: /8 TOS: 0 Metric: 74 r2.2.2.2#show ip ospf database summary 5.0.0.0 OSPF Router with ID (2.2.2.2) (Process ID 2) Summary Net Link States (Area 0) LS age: 1687 Options: (No TOS-capability, DC) LS Type: Summary Links(Network) Link State ID: 5.0.0.0 (summary Network Number) !--- The ABR (Router 2.2.2.2) advertises !--- 5.0.0.0/8 into area 0. Advertising Router: 2.2.2.2 LS Seq Number: 80000004 Checksum: 0x8864 Length: 28 Network Mask: /8 TOS: 0 Metric: 64 r2.2.2.2#show ip ospf database summary 6.0.0.0 OSPF Router with ID (2.2.2.2) (Process ID 2) Summary Net Link States (Area 1) LS age: 1697 Options: (No TOS-capability, DC) LS Type: Summary Links(Network) Link State ID: 6.0.0.0 (summary Network Number) !--- The ABR (Router 2.2.2.2) advertises !--- 6.0.0.0/8 into area 1. Advertising Router: 2.2.2.2 LS Seq Number: 8000001C Checksum: 0x7894 Length: 28 Network Mask: /8 TOS: 0 Metric: 1
在本例中,不需要ASBR彙總LSA,因為ABR建立外部LSA,並且可以在區域0內訪問ABR。通過檢視資料庫示例OSPF如何將外部路由傳播到多個區域,將此示例與NSSA是正常區域的場景進行比較。
此路由表輸出顯示9.0.0.0稱為每台路由器的OSPF路由的不同型別。
r1.1.1.1#show ip route 9.0.0.0 Routing entry for 9.0.0.0/8 Known via "static", distance 1, metric 0 Redistributing via ospf 4 Advertised by ospf 4 metric 5 metric-type 1 Routing Descriptor Blocks: * 4.0.0.2 Route metric is 0, traffic share count is 1 r2.2.2.2#show ip route ospf O 4.0.0.0/8 [110/74] via 5.0.0.1, 01:10:13, Serial0/1/0 O N1 9.0.0.0/8 [110/79] via 5.0.0.1, 01:07:20, Serial0/1/0 R3.3.3.3#show ip route ospf O IA 4.0.0.0/8 [110/75] via 6.0.0.2, 02:11:14, ATM2/0.20 O IA 5.0.0.0/8 [110/65] via 6.0.0.2, 03:10:41, ATM2/0.20 O E1 9.0.0.0/8 [110/80] via 6.0.0.2, 02:08:11, ATM2/0.20
目前尚無適用於此組態的具體疑難排解資訊。
修訂 | 發佈日期 | 意見 |
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1.0 |
10-Aug-2005 |
初始版本 |