OSPFでのDR/BDRの選出を確認する (ルータIDを変更する)

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OSPFでのDR/BDRの選出を確認する (ルータIDを変更する)

※ 前の「シナリオ」の続きとして記載しています。

RT-A にループバックインターフェイスを設定し、RT-A のルータ ID を変えなさい。

lo0 のIPアドレス	192.168.2.1/32

＜ RT-A ＞
RT-A# conf t
Enter configuration commands, one per line.  End with CNTL/Z.
RT-A(config)# int lo0
RT-A(config-if)# ip add 192.168.2.1 255.255.255.255
RT-A(config-if)# ^Z
RT-A#

RT-A で、sh ip ospf int f0/0 コマンドを実行しなさい。

＜ RT-A ＞
RT-A# sh ip ospf int f0/0
FastEthernet0/0 is up, line protocol is up
  Internet Address 192.168.1.1/24, Area 0, Attached via Network Statement
  Process ID 1, Router ID 192.168.1.1, Network Type BROADCAST, Cost: 1   ← ルータ ID は 192.168.1.1
  Topology-MTID    Cost    Disabled    Shutdown      Topology Name
        0           1         no          no            Base
  Transmit Delay is 1 sec, State DROTHER, Priority 1                     ← RT-A は DROTHER
  Designated Router (ID) 192.168.1.2, Interface address 192.168.1.2
  Backup Designated router (ID) 192.168.1.4, Interface address 192.168.1.4
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    oob-resync timeout 40
    Hello due in 00:00:02
  Supports Link-local Signaling (LLS)
  Cisco NSF helper support enabled
  IETF NSF helper support enabled
  Index 1/1, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 0, maximum is 1
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 3, Adjacent neighbor count is 2
    Adjacent with neighbor 192.168.1.2  (Designated Router)
    Adjacent with neighbor 192.168.1.4  (Backup Designated Router)
  Suppress hello for 0 neighbor(s)
RT-A#

RT-A のルータ ID は変わっていません。

RT-A の設定を保存し、RT-A を再起動させなさい。

＜ RT-A ＞
RT-A# copy run start
Destination filename [startup-config]? < Enter >
Building configuration...
[OK]
RT-A# reload
Proceed with reload? [confirm] < Enter >

RT-A が完全に起動した後、sh ip ospf int f0/0 コマンドを実行しなさい。

＜ RT-A ＞
RT-A# sh ip ospf int f0/0
FastEthernet0/0 is up, line protocol is up
  Internet Address 192.168.1.1/24, Area 0, Attached via Network Statement
  Process ID 1, Router ID 192.168.2.1, Network Type BROADCAST, Cost: 1   ← ルータ ID  は 192.168.2.1
  Topology-MTID    Cost    Disabled    Shutdown      Topology Name
        0           1         no          no            Base
  Transmit Delay is 1 sec, State DROTHER, Priority 1                     ← RT-A は DROTHER
  Designated Router (ID) 192.168.1.2, Interface address 192.168.1.2
  Backup Designated router (ID) 192.168.1.4, Interface address 192.168.1.4
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    oob-resync timeout 40
    Hello due in 00:00:01
  Supports Link-local Signaling (LLS)
  Cisco NSF helper support enabled
  IETF NSF helper support enabled
  Index 1/1, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 1, maximum is 1
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 3, Adjacent neighbor count is 2
    Adjacent with neighbor 192.168.1.2  (Designated Router)
    Adjacent with neighbor 192.168.1.4  (Backup Designated Router)
  Suppress hello for 0 neighbor(s)
RT-A#

RT-A のルータ ID が 192.168.2.1 になりました。

RT-A で、sh ip ospf neighbor コマンドを実行しなさい。

＜ RT-A ＞
RT-A# sh ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface
192.168.1.2       1   FULL/DR         00:00:38    192.168.1.2     FastEthernet0/0   ← RT-B
192.168.1.3       1   2WAY/DROTHER    00:00:33    192.168.1.3     FastEthernet0/0   ← RT-C
192.168.1.4       1   FULL/BDR        00:00:34    192.168.1.4     FastEthernet0/0   ← RT-D
RT-A#

RT-A を再起動させて RT-A のルータ ID は変わりましたが、DR/BDR に変更はありません。

ルータ名	プライオリティ	ルータ ID	機能
RT-A	1	192.168.2.1	DROTHER
RT-B	1	192.168.1.2	DR
RT-C	1	192.168.1.3	DROTHER
RT-D	1	192.168.1.4	BDR

router-id コマンドで、RT-C にルータ ID を設定しなさい。

ルータ ID	192.168.3.1

＜ RT-C ＞
RT-C# conf t
Enter configuration commands, one per line.  End with CNTL/Z.
RT-C(config)# router ospf 1
RT-C(config-router)# router-id 192.168.3.1
Reload or use "clear ip ospf process" command, for this to take effect
RT-C(config-router)# ^Z
RT-C#

RT-C で、sh ip ospf int f0/0 コマンドを実行しなさい。

＜ RT-C ＞
RT-C# sh ip ospf int f0/0
FastEthernet0/0 is up, line protocol is up
  Internet Address 192.168.1.3/24, Area 0, Attached via Network Statement
  Process ID 1, Router ID 192.168.1.3, Network Type BROADCAST, Cost: 1   ← ルータ ID は 192.168.1.3
  Topology-MTID    Cost    Disabled    Shutdown      Topology Name
        0           1         no          no            Base
  Transmit Delay is 1 sec, State DROTHER, Priority 1
  Designated Router (ID) 192.168.1.2, Interface address 192.168.1.2
  Backup Designated router (ID) 192.168.1.4, Interface address 192.168.1.4
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    oob-resync timeout 40
    Hello due in 00:00:08
  Supports Link-local Signaling (LLS)
  Cisco NSF helper support enabled
  IETF NSF helper support enabled
  Index 1/1, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 0, maximum is 1
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 3, Adjacent neighbor count is 2
    Adjacent with neighbor 192.168.1.2  (Designated Router)
    Adjacent with neighbor 192.168.1.4  (Backup Designated Router)
  Suppress hello for 0 neighbor(s)
RT-C#

RT-C のルータ ID は変わっていません。

RT-C で、clear ip ospf process コマンドを実行後、sh ip ospf int f0/0 コマンドを実行しなさい。

＜ RT-C ＞
RT-C#clear ip ospf process
Reset ALL OSPF processes? [no]: y
RT-C# sh ip ospf int f0/0
FastEthernet0/0 is up, line protocol is up
  Internet Address 192.168.1.3/24, Area 0, Attached via Network Statement
  Process ID 1, Router ID 192.168.3.1, Network Type BROADCAST, Cost: 1   ← ルータ ID は 192.168.3.1
  Topology-MTID    Cost    Disabled    Shutdown      Topology Name
        0           1         no          no            Base
  Transmit Delay is 1 sec, State DROTHER, Priority 1
  Designated Router (ID) 192.168.1.2, Interface address 192.168.1.2
  Backup Designated router (ID) 192.168.1.4, Interface address 192.168.1.4
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    oob-resync timeout 40
    Hello due in 00:00:00
  Supports Link-local Signaling (LLS)
  Cisco NSF helper support enabled
  IETF NSF helper support enabled
  Index 1/1, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 0, maximum is 1
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 3, Adjacent neighbor count is 2
    Adjacent with neighbor 192.168.1.2  (Designated Router)
    Adjacent with neighbor 192.168.1.4  (Backup Designated Router)
  Suppress hello for 0 neighbor(s)
RT-C#

RT-C のルータ ID が 192.168.3.1 になりました。

RT-C で、sh ip ospf neighbor コマンドを実行しなさい。

＜ RT-C ＞
RT-C# sh ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface
192.168.1.2       1   FULL/DR         00:00:37    192.168.1.2     FastEthernet0/0   ← RT-B
192.168.1.4       1   FULL/BDR        00:00:38    192.168.1.4     FastEthernet0/0   ← RT-D
192.168.2.1       1   2WAY/DROTHER    00:00:31    192.168.1.1     FastEthernet0/0   ← RT-A
RT-C#

RT-C のルータ ID は変わりましたが、DR/BDR に変更はありません。

ルータ名	プライオリティ	ルータ ID	機能
RT-A	1	192.168.2.1	DROTHER
RT-B	1	192.168.1.2	DR
RT-C	1	192.168.3.1	DROTHER
RT-D	1	192.168.1.4	BDR

SW-A の電源を [OFF] → [ON] しなさい。

SW-A が完全に起動し RT-C で、sh ip ospf int f0/0 コマンドを実行しなさい。

＜ RT-C ＞
RT-C# sh ip ospf int f0/0
FastEthernet0/0 is up, line protocol is up
  Internet Address 192.168.1.3/24, Area 0, Attached via Network Statement
  Process ID 1, Router ID 192.168.3.1, Network Type BROADCAST, Cost: 1
  Topology-MTID    Cost    Disabled    Shutdown      Topology Name
        0           1         no          no            Base
  Transmit Delay is 1 sec, State DR, Priority 1                             ← RT-C が DR
  Designated Router (ID) 192.168.3.1, Interface address 192.168.1.3
  Backup Designated router (ID) 192.168.2.1, Interface address 192.168.1.1
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    oob-resync timeout 40
    Hello due in 00:00:05
  Supports Link-local Signaling (LLS)
  Cisco NSF helper support enabled
  IETF NSF helper support enabled
  Index 1/1, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 1, maximum is 1
  Last flood scan time is 0 msec, maximum is 4 msec
  Neighbor Count is 3, Adjacent neighbor count is 3
    Adjacent with neighbor 192.168.1.2
    Adjacent with neighbor 192.168.1.4
    Adjacent with neighbor 192.168.2.1  (Backup Designated Router)
  Suppress hello for 0 neighbor(s)
RT-C#

RT-C で、sh ip ospf neighbor コマンドを実行しなさい。

＜ RT-C ＞
RT-A# sh ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface
192.168.1.2       1   FULL/DROTHER    00:00:38    192.168.1.2     FastEthernet0/0   ← RT-B
192.168.1.4       1   FULL/DROTHER    00:00:33    192.168.1.4     FastEthernet0/0   ← RT-D
192.168.2.1       1   FULL/BDR        00:00:39    192.168.1.1     FastEthernet0/0   ← RT-A
RT-A#

ルータ ID の大きい順に DR/BDR が決定し、それ以外は DROTHER になっています。

ルータ名	プライオリティ	ルータ ID	機能
RT-A	1	192.168.2.1	BDR
RT-B	1	192.168.1.2	DROTHER
RT-C	1	192.168.3.1	DR
RT-D	1	192.168.1.4	DROTHER

DR ルータは、BDR とも DROTHER ともアジャセンシー関係を確立します。
また、BDR ルータも同様に DR とも DROTHER ともアジャセンシー関係を確立します。
DROTHER 同士のみネイバー関係までになります。

※ 次の「シナリオ」に続きます。