OSPF LSA Types (2), LSA Type 1: Router LSA

(接前文)

Type 1 LSA定義一個OSPF路由器本身,和直接接在他身上的所有"網路物件"的連結.

"網路物件"指的是: (1) OSPF 路由器,和 (2) OSPF 設定中定義的網段.

附圖中可以看得出來,R1接了三個物件: (1) R2, (2)10.12.12.0/24網段, 和 (3) 10.1.1.0/24網段.

不過, 100.100.100.0/24網段,就不在其中之一, 這是因為100.100.100.0/24並沒有在OSPF設定中被宣告, 所以不算!

我們可以用這個命令 show ip ospf database router 0.0.0.1 ,來印出定義R1的Type 1 Router LSA. 其中"0.0.0.1"是 R1的Router ID, 也就是R1的在OSPF協定中,被稱呼的名字.

R1>show ip ospf database router 0.0.0.1

OSPF Router with ID (0.0.0.1) (Process ID 1)

Router Link States (Area 0)

LS age: 1724
Options: (No TOS-capability, DC)
LS Type: Router Links
Link State ID: 0.0.0.1
Advertising Router: 0.0.0.1
LS Seq Number: 80000003
Checksum: 0x54DC
Length: 60
AS Boundary Router
Number of Links: 3

Link connected to: another Router (point-to-point)
(Link ID) Neighboring Router ID: 0.0.0.2
(Link Data) Router Interface address: 10.12.12.1
Number of TOS metrics: 0
TOS 0 Metrics: 64

Link connected to: a Stub Network
(Link ID) Network/subnet number: 10.12.12.0
(Link Data) Network Mask: 255.255.255.0
Number of TOS metrics: 0
TOS 0 Metrics: 64

Link connected to: a Stub Network
(Link ID) Network/subnet number: 10.1.1.0
(Link Data) Network Mask: 255.255.255.0
Number of TOS metrics: 0
TOS 0 Metrics: 10


R1>

相同的方式,我們也可以列出定義R2的Type 1 Router LSA.我們使用相同的命令 "show ip ospf database router 0.0.0.2"

R1>show ip ospf database router 0.0.0.2

OSPF Router with ID (0.0.0.1) (Process ID 1)

Router Link States (Area 0)

Routing Bit Set on this LSA
LS age: 1508
Options: (No TOS-capability, DC)
LS Type: Router Links
Link State ID: 0.0.0.2
Advertising Router: 0.0.0.2
LS Seq Number: 80000004
Checksum: 0x84A8
Length: 60
Area Border Router
Number of Links: 3

Link connected to: another Router (point-to-point)
(Link ID) Neighboring Router ID: 0.0.0.1
(Link Data) Router Interface address: 10.12.12.2
Number of TOS metrics: 0
TOS 0 Metrics: 64

Link connected to: a Stub Network
(Link ID) Network/subnet number: 10.12.12.0
(Link Data) Network Mask: 255.255.255.0
Number of TOS metrics: 0
TOS 0 Metrics: 64

Link connected to: a Stub Network
(Link ID) Network/subnet number: 10.2.2.0
(Link Data) Network Mask: 255.255.255.0
Number of TOS metrics: 0
TOS 0 Metrics: 10


R1>

大家應該有注意到,R2事實上接上了不只三個網路物件.怎麼會只有印出三個? 這是因為OSPF協定的每一個區域(Area)當中,都有自己的連線狀態資料集合(Link State Database). 列出來的這三個,正是含在R1和R2共同連接的零號區域(Area 0)中.


(待續)

OSPF LSA Types (1)

為了幫助了解OSPF的LSA型態到底有哪幾種,我設計了以下這個例子,方便大家隨時可以參考!

這個例子是使用4部Ｒouter啟動OSPF協定,其中R1屬於Area 0, R3和R4屬於Area 1. R2則是介於這兩個Area中間的ABR,一半的WAN和LAN網路卡分別屬於這兩個Area.

(待續)

架構圖
R1設定
R2設定
R3設定
R4設定