IPv6 OSPFv3路由協議（續三）

區域內前綴 LSA （ Intra-Area-Prefix-LSA ）

該類型LSA在本區域內傳播，具備如下兩種功能之一：經過參考網絡LSA把IPv6地址前綴與轉遞網絡（transit network）相關聯；或者經過參考路由器LSA把IPv6地址前綴與路由器相關聯。一臺路由器能夠爲給定的區域產生多個該類型的LSA，這些LSA使用鏈路狀態ID字段（Link State ID）區分。DR爲它所表明的鏈路產生一個或多個該類型的LSA，向整個區域內通告該鏈路的地址前綴。

Intra Area Prefix LSA描述了Router LSA和Network LSA所攜帶的路由信息，所以在Intra Area Prefix LSA中須要標明該LSA引用的Router LSA或Network LSA，這是經過Referenced LS Type、Referenced Link State ID和Referenced AdvertisingRouter字段來聯合標識的。

主要字段的解釋以下：

? # Prefixes：包含的IPv6 地址前綴的個數。

? Referenced LS Type：引用LSA 的類型，取值爲1 代表該LSA 與RouterLSA 相關，取值爲2 代表該LSA 與Network LSA 相關。

? Referenced Link State ID：引用LSA 的Link State ID。若是引用的是Router LSA，此字段值爲0；若是引用的是Network LSA，此字段值爲DR在該條鏈路上的Interface ID。

? Referenced Advertising Router：引用LSA 的發佈路由器。若是引用的是Router LSA，此字段值爲產生該LSA 路由器的Router ID；若是引用的是Network LSA，此字段值爲DR 的Router ID。

以下圖所示：

3.1.3 OSPFv3路由協議工做機制

OSPFv3協議的工做原理與OSPFv2的工做原理是同樣的，由於OSPFv3是在OSPFv2的基礎之上修改而成的。在路由器上可使用show ipv6 ospf adj來了解其鄰居、鄰接之間造成的工做過程，以下所示：

R1#debug ipv6 ospf adj

OSPFv3 adjacency events debugging is on

R1#clear ipv6 ospf process

Reset ALL OSPF processes? [no]: yes

R1#

*Sep 5 11:56:57.747: OSPFv3: Interface Loopback0 going Down

*Sep 5 11:56:57.747: OSPFv3: Interface Ethernet1/0 going Down

*Sep 5 11:56:57.747: OSPFv3: Neighbor change Event on interface Ethernet1/0

*Sep 5 11:56:57.751: OSPFv3: DR/BDR election on Ethernet1/0

*Sep 5 11:56:57.751: OSPFv3: Elect BDR 0.0.0.0

*Sep 5 11:56:57.751: OSPFv3: Elect DR 2.2.2.2

*Sep 5 11:56:57.751: OSPFv3: Elect BDR 0.0.0.0

*Sep 5 11:56:57.751: OSPFv3: Elect DR 2.2.2.2

*Sep 5 11:56:57.751: DR: 2.2.2.2 (Id) BDR: none

*Sep 5 11:56:57.755: OSPFv3: 2.2.2.2 address FE80::C800:4CFF:FE18:1C on Ethernet1/0 is dead, state DOWN

*Sep 5 11:56:57.755: %OSPFv3-5-ADJCHG: Process 10, Nbr 2.2.2.2 on Ethernet1/0 from FULL to DOWN, Neighbor Down: Interface down or detached

*Sep 5 11:56:57.759: OSPFv3: Neighbor change Event on interface Ethernet1/0

*Sep 5 11:56:57.759: OSPFv3: DR/BDR election on Ethernet1/0

*Sep 5 11:56:57.759: OSPFv3: Elect BDR 0.0.0.0

*Sep 5 11:56:57.763: OSPFv3: Elect DR 0.0.0.0

*Sep 5 11:56:57.763: DR: none BDR: none

*Sep 5 11:56:57.763: OSPFv3: Remember old DR 2.2.2.2 (id)

*Sep 5 11:56:57.767: OSPFv3: Interface Loopback0 going Up

*Sep 5 11:56:57.767: OSPFv3: Interface Ethernet1/0 going Up

*Sep 5 11:56:57.787: OSPFv3: 2 Way Communication to 2.2.2.2 on Ethernet1/0, state 2WAY

*Sep 5 11:56:57.787: OSPFv3: Backup seen Event before WAIT timer on Ethernet1/0

*Sep 5 11:56:57.791: OSPFv3: DR/BDR election on Ethernet1/0

*Sep 5 11:56:57.791: OSPFv3: Elect BDR 1.1.1.1

*Sep 5 11:56:57.791: OSPFv3: Elect DR 2.2.2.2

*Sep 5 11:56:57.791: OSPFv3: Elect BDR 1.1.1.1

*Sep 5 11:56:57.791: OSPFv3: Elect DR 2.2.2.2

*Sep 5 11:56:57.795: DR: 2.2.2.2 (Id) BDR: 1.1.1.1 (Id)

*Sep 5 11:56:57.795: OSPFv3: Send DBD to 2.2.2.2 on Ethernet1/0 seq 0x13E3 opt 0x0013 flag 0x7 len 28

*Sep 5 11:56:57.855: OSPFv3: Rcv DBD from 2.2.2.2 on Ethernet1/0 seq 0xA36 opt 0x0013 flag 0x7 len 28 mtu 1500 state EXSTART

*Sep 5 11:56:57.859: OSPFv3: NBR Negotiation Done. We are the SLAVE

*Sep 5 11:56:57.859: OSPFv3: Send DBD to 2.2.2.2 on Ethernet1/0 seq 0xA36 opt 0x0013 flag 0x0 len 28

*Sep 5 11:56:57.879: OSPFv3: Rcv DBD from 2.2.2.2 on Ethernet1/0 seq 0xA37 opt 0x0013 flag 0x3 len 188 mtu 1500 state EXCHANGE

*Sep 5 11:56:57.883: OSPFv3: Send DBD to 2.2.2.2 on Ethernet1/0 seq 0xA37 opt 0x0013 flag 0x0 len 28

*Sep 5 11:56:57.883: OSPFv3: Database request to 2.2.2.2

*Sep 5 11:56:57.887: OSPFv3: sent LS REQ packet to FE80::C800:4CFF:FE18:1C, length 96

*Sep 5 11:56:58.131: OSPFv3: Rcv DBD from 2.2.2.2 on Ethernet1/0 seq 0xA38 opt 0x0013 flag 0x1 len 28 mtu 1500 state EXCHANGE

*Sep 5 11:56:58.131: OSPFv3: Exchange Done with 2.2.2.2 on Ethernet1/0

*Sep 5 11:56:58.131: OSPFv3: Send DBD to 2.2.2.2 on Ethernet1/0 seq 0xA38 opt 0x0013 flag 0x0 len 28

*Sep 5 11:56:58.139: OSPFv3: Synchronized with 2.2.2.2 on Ethernet1/0, state FULL

*Sep 5 11:56:58.139: %OSPFv3-5-ADJCHG: Process 10, Nbr 2.2.2.2 on Ethernet1/0 from LOADING to FULL, Loading Done

*Sep 5 11:57:00.691: OSPFv3: Neighbor change Event on interface Ethernet1/0

*Sep 5 11:57:00.691: OSPFv3: DR/BDR election on Ethernet1/0

*Sep 5 11:57:00.691: OSPFv3: Elect BDR 1.1.1.1

*Sep 5 11:57:00.695: OSPFv3: Elect DR 2.2.2.2

*Sep 5 11:57:00.695: DR: 2.2.2.2 (Id) BDR: 1.1.1.1 (Id)

3.1.3 OSPFv3多區域配置

在配置OSPFv3路由協議以前，須要注意到如下幾點：

? 接口要參與OSPFv3運行，必須在接口配置模式下明確啓動。而在OSPFv2中，這是經過在OSPF路由配置模式下，經過network命令間接啓動。

? 若是配置接口參與OSPFv3運行，那麼接口上全部的地址都將參與IPv6運行。而在OSPFv2中，全部地址都必須經過network命令啓動。

? 在運行OSPFv3的環境中，在同一個鏈路上可以容許運行多個OSPF實體，該鏈路所連的不一樣設備能夠選擇參與運行某一個OSPF實體。OSPFv2並不支持該功能。

? 每臺運行OSPFv3進程的設備都必須使用一個router ID來標識，router ID使用IPv4地址格式。不一樣於OSPFv2，OSPFv2進程將自動獲取IPv4地址做爲router ID，設備在啓動OSPFv3進程後，用戶必須使用router-id命令爲OSPFv3進程配置router ID，不然OSPFv3進程將沒法啓動。

本實驗的網絡拓撲以下圖所示：

具體配置以下所示：

路由器 R1 配置

ipv6 unicast-routing

!

interface Loopback0

no ip address

ipv6 address 2001:10::1/64

ipv6 ospf 10 area 10

!

interface Ethernet1/0

no ip address

duplex full

ipv6 address 2001:1::1/64

ipv6 enable

ipv6 ospf 10 area 10

!

interface Ethernet1/1

no ip address

duplex full

ipv6 address 2001:5::1/64

ipv6 enable

!

ipv6 router ospf 10

router-id 1.1.1.1

log-adjacency-changes

路由器 R2 配置

ipv6 unicast-routing

!

interface Ethernet1/0

no ip address

duplex full

ipv6 address 2001:1::2/64

ipv6 enable

ipv6 ospf 10 area 10

!

interface Ethernet1/1

no ip address

duplex full

ipv6 address 2001:2::1/64

ipv6 enable

ipv6 ospf 10 area 0

!

ipv6 router ospf 10

router-id 2.2.2.2

log-adjacency-changes

!

路由器 R3 配置

ipv6 unicast-routing

!

interface Ethernet1/0

no ip address

duplex full

ipv6 address 2001:2::2/64

ipv6 enable

ipv6 ospf 10 area 0

!

interface Ethernet1/1

no ip address

duplex full

ipv6 address 2001:3::1/64

ipv6 enable

ipv6 ospf 10 area 20

!

ipv6 router ospf 10

router-id 3.3.3.3

log-adjacency-changes

路收器 R4 配置

ipv6 unicast-routing

!

interface Loopback0

no ip address

ipv6 address 2001:11::1/64

ipv6 ospf 10 area 20

!

interface Ethernet1/0

no ip address

duplex full

ipv6 address 2001:3::2/64

ipv6 enable

ipv6 ospf 10 area 20

!

interface Ethernet1/1

no ip address

duplex full

ipv6 address 2001:4::1/64

ipv6 enable

ipv6 ospf 10 area 20

!

ipv6 router ospf 10

router-id 4.4.4.4

log-adjacency-changes

可使用show命令來查看路由表和鄰居狀態。

R1#sh ipv6 route

IPv6 Routing Table - 11 entries

Codes: C - Connected, L - Local, S - Static, R - RIP, B - BGP

U - Per-user Static route

I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary

O - OSPF intra, OI - OSPF inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2

ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2

C 2001:1::/64 [0/0]

via ::, Ethernet1/0

L 2001:1::1/128 [0/0]

via ::, Ethernet1/0

OI 2001:2::/64 [110/20]

via FE80::C800:4CFF:FE18:1C, Ethernet1/0

OI 2001:3::/64 [110/30]

via FE80::C800:4CFF:FE18:1C, Ethernet1/0

OI 2001:4::/64 [110/30]

via FE80::C800:4CFF:FE18:1C, Ethernet1/0

C 2001:5::/64 [0/0]

via ::, Ethernet1/1

L 2001:5::1/128 [0/0]

via ::, Ethernet1/1

C 2001:10::/64 [0/0]

via ::, Loopback0

L 2001:10::1/128 [0/0]

via ::, Loopback0

L FE80::/10 [0/0]

via ::, Null0

L FF00::/8 [0/0]

via ::, Null0

R3#sh ipv6 ospf neighbor

Neighbor ID Pri State Dead Time Interface ID Interface

2.2.2.2 1 FULL/DR 00:00:35 6 Ethernet1/0

4.4.4.4 1 FULL/DR 00:00:33 6 Ethernet1/1