dead-interval の値変更



トポロジ

R1 s1/0 ----------------s1/0 R2
        192.168.0.0/24

条件
・R1-R2間にてOSPFを稼動させ、dead-intervalを40に設定してください。
・ip ospf dead-interval, ip ospf hello-interval は使用しないでください。


まず下記設定からスタートです。

R1
interface Serial1/0
ip add 192.168.0.0 255.255.255.0

router ospf 1
net 192.168.0.0 0.0.0.255 area 0

R2
interface Serial1/0
ip add 192.168.0.2 255.255.255.0

router ospf 1
net 192.168.0.0 0.0.0.255 area 0

上記状態で、sh ip ospf int と見ると既にdead-interval が 40 となっているので問題はクリアです。


R1#sh ip ospf int
Serial1/0 is up, line protocol is up
  Internet Address 192.168.0.1/24, Area 0
  Process ID 1, Router ID 192.168.0.1, Network Type POINT_TO_POINT, Cost: 64
  Transmit Delay is 1 sec, State POINT_TO_POINT,
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    oob-resync timeout 40
    Hello due in 00:00:07
  Supports Link-local Signaling (LLS)
  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 1, Adjacent neighbor count is 1
    Adjacent with neighbor 192.168.0.2
  Suppress hello for 0 neighbor(s)


今回の構成では、Serialインターフェースの直つなぎのため network type が point-to-point となり、
Hello 10,Dead 40 となりましたが、non-broadcast の場合などは、Hello 30,Dead 120 となります。

こんなときに Dead interval をかえる方法としてはまず、ip ospf dead-interval を実行します。

dead-interval を 150　にかえたい場合は、

(config-int)#ip ospf dead-interval 150
R1#sh ip ospf interface
Serial1/0 is up, line protocol is up
  Internet Address 192.168.0.1/24, Area 0
  Process ID 1, Router ID 192.168.0.1, Network Type POINT_TO_POINT, Cost: 64
  Transmit Delay is 1 sec, State POINT_TO_POINT,
  Timer intervals configured, Hello 10, Dead 150, Wait 150, Retransmit 5
    oob-resync timeout 150
    Hello due in 00:00:07
  Supports Link-local Signaling (LLS)
  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 1, Adjacent neighbor count is 1
    Adjacent with neighbor 192.168.0.2
  Suppress hello for 0 neighbor(s)


もしくは、ip ospf hello-interval を実行します。Hello-interval を設定した場合、
Dead-interval は Hello の　4倍の間隔になります。


(config-int)#ip ospf hello-interval 15
R1#sh ip ospf inter
Serial1/0 is up, line protocol is up
  Internet Address 192.168.0.1/24, Area 0
  Process ID 1, Router ID 192.168.0.1, Network Type POINT_TO_POINT, Cost: 64
  Transmit Delay is 1 sec, State POINT_TO_POINT,
  Timer intervals configured, Hello 15, Dead 60, Wait 60, Retransmit 5
    oob-resync timeout 60
    Hello due in 00:00:11
  Supports Link-local Signaling (LLS)
  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 1, Adjacent neighbor count is 1
    Adjacent with neighbor 192.168.0.2
  Suppress hello for 0 neighbor(s)

参考 http://www.netagency.biz/ccie/modules/xhnewbb/viewtopic.php?topic_id=28
 手抜きですが、以上です。

更新日：2012年8月24日
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