Cisco OSPF LSA 类型详解指南

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OSPF LSA Types: The Ultimate Guide

OSPF LSA Types – OSPF LSA 类型 –

OSPF uses LSAs or Link state Advertisements to share information of each network and populate the LSDB (Link State Database). The LSAs are used by routers to exchange topology information. An LSA contains routing and topology information that describe a part of an OSPF network. Routers exchange LSAs and learn the complete topology of the network until all routers have the exact same topology database. Infact, OSPF sends updates (LSAs) when there is a change to one of its links. LSAs are additionally refreshed every 30 minutes.
OSPF 使用 LSA 或链路状态通告来共享每个网络的信息并填充 LSDB（链路状态数据库）。路由器使用 LSA 来交换拓扑信息。LSA 包含描述 OSPF 网络一部分的路由和拓扑信息。路由器交换 LSA 并了解网络的完整拓扑，直到所有路由器都具有完全相同的拓扑数据库。事实上，当其中一个链接发生更改时，OSPF 会发送更新（LSA）。LSA 每 30 分钟额外刷新一次。

All OSPF LSA Types are mentioned in below table –

下表提到了所有 OSPF LSA 类型 –

Types	Description
LSA Type 1	Router LSA
LSA Type 2	Network LSA
LSA Type 3 or 4	Summary LSA & ASBR LSA
LSA Type 5	Autonomous System External LSA
LSA Type 6	Multicast OSPF LSA
LSA Type 7	Defined for Not-So-Stubby-Areas
LSA Type 8	External Attribute LSA for BGP
LSA Type 9,10,11	Opaque LSA

LSA Type 1: Router LSA

This LSA type is flooded by every router within an area
此 LSA 类型被区域内的每个路由器泛洪
The LSA consists of information about directly connected links
LSA 包含有关直接连接链接的信息
It is identified by the Router ID or the originating router
它由路由器 ID 或原始路由器标识
It floods within an area and the LSA Type 1 does not cross the ABR.
它在一个区域内泛洪，LSA Type 1 不会穿过 ABR。
We see this as “O” routes in the routing table
我们在路由表中将其视为“O”路由
LSA 1 – O, Router LSA contains all Link IDs – network, generated by every router and is local to the area.
LSA 1 – O，路由器 LSA 包含所有链路 ID – 网络，由每个路由器生成，并且是该区域的本地设备。
This LSA does not cross ABR.
此 LSA 不跨越 ABR。

LSA Type 2: Network LSA

Generated by the DR Router on the broadcast network
由广播网络上的 DR 路由器生成
It includes the network ID, subnet mask and also the list of attached routers in the transit
它包括网络 ID、子网掩码以及传输中连接的路由器列表
In OSPF we can have one Network LSA or Type 2 LSA for each transit broadcast of NBMA Network
在 OSPF 中，我们可以为 NBMA 网络的每个传输广播使用一个网络 LSA 或 Type 2 LSA
This LSA also can be flooded only within the area and cannot cross the ABR
该 LSA 也只能在区域内被泛洪，不能越过 ABR
We see this as “O” routes in the routing table
我们在路由表中将其视为“O”路由
LSA 2 – O, Network LSA contains all routers attached to the segment, generated by DR and is local to the area
LSA 2 – O，网络 LSA 包含连接到分段的所有路由器，由 DR 生成，并且是该区域的本地路由器

LSA Type 3: Summary LSA

The Type 3 LSA is used to share the network information with other areas. Inter-area ( IA)
Type 3 LSA 用于与其他区域共享网络信息。区域间（ IA）
These LSAs are advertised by the ABR Router
这些 LSA 由 ABR 路由器通告
These LSA are represented in the routing table as “OIA” routes
这些 LSA 在路由表中表示为“OIA”路由
To flood the information through the Autonomous System, they are regenerated by the ABRs following subsequently
为了使信息通过自治系统，它们由随后的 ABRs 重新生成
LSA 3 – OIA, Network Summary LSA describes network from another area, generated by ABR and is propagated between areas
LSA 3 – OIA，网络摘要 LSA 描述来自另一个区域的网络，由 ABR 生成并在区域之间传播
It contains network ID and subnet mask
它包含网络 ID 和子网掩码

LSA Type 4: Summary ASBR LSA

This LSA type is also known as summary LSA is used to advertise about the ASBR to other areas in the same autonomous system.
这种 LSA 类型也称为摘要 LSA，用于向同一自治系统中的其他区域通告 ASBR。
It is generated by the ABR of the originating area.
它由原始区域的 ABR 生成。
These type of LSAs are flooded throughout the Autonomous System
这些类型的 LSA 在整个自治系统中被泛洪
These LSA will contain the Router ID of the ASBR only
这些 LSA 将仅包含 ASBR 的路由器 ID
LSA 4 – OIA, Summary ASB Link States, generated by the ABR and is propagated between areas
LSA 4 – OIA，摘要 ASB 链路状态，由 ABR 生成并在区域之间传播

LSA Type 5: External LSA

These are advertised by the ASBR only and also owned by the ASBR
这些仅由 ASBR 发布广告，也归 ASBR 所有
These LSAs are used to advertise networks from other Autonomous systems
这些 LSA 用于通告来自其他自治系统的网络
These LSAs are flooded throughout the entire Autonomous System
这些 LSA 在整个自治系统中被泛洪
The advertising router ID is not changed throughout the AS when it is propagating.
广播路由器 ID 在传播时不会在整个 AS 中更改。
An LSA Type 4 is used to ~~find~~ an ASBR
LSA Type 4 用于查找 ASBR

斐夷所非注 此处作者描述用词不妥—— 不是查找，而是宣告

LSA Type 4 的功能：
宣告 ASBR 的位置：它告诉其他 OSPF 路由器 ASBR 的位置，从而帮助路由器了解如何到达此 ASBR。
区域信息：包含了 ASBR 所在区域的信息，以便 OSPF 路由器能够如何进行路由选择。

Routes are not summarized by default
默认情况下，不会汇总路由
LSA 5 – O E1, O E2, External Link States, generated by ASBR and is propagated
LSA 5 – O E1、O E2、外部链路状态，由 ASBR 生成并传播

LSA Type 6: Multicast OSPF LSA

These are used when routing using multicast (the MODPF Routing protocol)
在使用多播（MODPF 路由协议）进行路由时，将使用这些协议

斐夷所非注 此处应为 MOSPF

These LSAs are not supported by Cisco Routers
Cisco 路由器不支持这些 LSA

LSA Type 7: External LSA

As LSA Type 5 is not allowed in NSSA Areas, a solution to that was thought as LSA 7.
由于在 NSSA 区域不允许使用 LSA 类型 5，因此提出了一个解决方案，即使用 LSA 类型 7。
It carries similar information as a Type 5 LSA but this is not blocked in the NSSA Area.
它携带与 Type 5 LSA 类似的信息，但这在 NSSA 区域中不会被阻止。
When it reached the ABR it is translated back to Type 5 LSA and flooded into other areas.
当它到达 ABR 时，它被转换回 5 型 LSA 并泛洪到其他地区。
LSA 7 – O N1, O N2, NSSA External Link States, generated by ASBR into NSSA area and is propagated into area 0 as E1 or E2
LSA 7 – O N1、O N2、NSSA 外部链路状态，由 ASBR 生成到 NSSA 区域，并作为 E1 或 E2 传播到区域 0

LSA Type 8: External attributes LSA for Border Gateway Protocol (BGP)

This LSA Types is used to work with BGP.
此 LSA 类型用于处理 BGP。
Note – Below list of LSA9, 10 and 11 are called Opaque LSAs. Further detail on these LSA types is shared below –
注 – 以下 LSA9、10 和 11 列表称为不透明 LSA。有关这些 LSA 类型的更多详细信息，请参阅以下 –

LSA Type 9: Opaque LSA

This LSA types is Link-state in scope and is not flooded beyond the local network.
此 LSA 类型在范围内是链路状态，并且不会泛洪到本地网络之外。

LSA Type 10: Opaque LSA

The scope of this type of LSA is area-local. This LSA is not flooded beyond the borders of their associated area.
此类 LSA 的范围是区域本地的。该 LSA 不会被泛洪到其相关区域的边界之外。

LSA Type 11: Opaque LSA

This LSA is flooded throughout the Autonomous System (AS). Somewhat is can be related to Type-5 LSA is terms of flooding scope. There are 3 key features of Type11 LSAs –
此类 LSA 在整个自治系统（AS）中进行泛洪。在泛洪范围方面，它在某种程度上可以与 Type-5 LSA 相关联。Type-11 LSA 的三个主要特点是：