ネットワークのおべんきょしませんか？ Cisco CCNA/CCNP/CCIE、ネットワークスペシャリスト試験の勉強にピッタリ

トラブルの症状

Recieverが239.1.1.1のマルチキャストグループに参加しているにも関わらず、RPであるR2までの共有ツリーが作成されていません。R2、R3でshow ip mrouteは次のようになっています。

R2 show ip mroute

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R2#show ip mroute
IP Multicast Routing Table
Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,
       L - Local, P - Pruned, R - RP-bit set, F - Register flag,
       T - SPT-bit set, J - Join SPT, M - MSDP created entry,
       X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
       U - URD, I - Received Source Specific Host Report,
       Z - Multicast Tunnel, z - MDT-data group sender,
       Y - Joined MDT-data group, y - Sending to MDT-data group
Outgoing interface flags: H - Hardware switched, A - Assert winner
 Timers: Uptime/Expires
 Interface state: Interface, Next-Hop or VCD, State/Mode

(*, 224.0.1.40), 02:06:47/00:02:08, RP 0.0.0.0, flags: DCL
  Incoming interface: Null, RPF nbr 0.0.0.0
  Outgoing interface list:
    FastEthernet0/0, Forward/Sparse, 02:06:47/00:02:08
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R3 show ip mroute

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R3#show ip mroute
IP Multicast Routing Table
Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,
       L - Local, P - Pruned, R - RP-bit set, F - Register flag,
       T - SPT-bit set, J - Join SPT, M - MSDP created entry,
       X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
       U - URD, I - Received Source Specific Host Report,
       Z - Multicast Tunnel, z - MDT-data group sender,
       Y - Joined MDT-data group, y - Sending to MDT-data group
Outgoing interface flags: H - Hardware switched, A - Assert winner
 Timers: Uptime/Expires
 Interface state: Interface, Next-Hop or VCD, State/Mode
(*, 239.1.1.1), 00:00:15/00:02:44, RP 192.168.0.2, flags: SJC
  Incoming interface: Null, RPF nbr 0.0.0.0
  Outgoing interface list:
    FastEthernet1/0, Forward/Sparse, 00:00:15/00:02:44
(*, 224.0.1.40), 00:01:12/00:01:49, RP 0.0.0.0, flags: DCL
  Incoming interface: Null, RPF nbr 0.0.0.0
  Outgoing interface list:
    Tunnel23, Forward/Sparse, 00:01:12/00:01:49
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また、Sourceから239.1.1.1あてにマルチキャストパケットを送信しても、ルーティングされていません。Sourceから239.1.1.1あてにPingした結果は、次の通りです。

Source ping 239.1.1.1

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Source#ping 239.1.1.1

Type escape sequence to abort.
Sending 1, 100-byte ICMP Echos to 239.1.1.1, timeout is 2 seconds:
.
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トラブルを切り分けるために、Sourceから239.1.1.1へ連続してパケットを送信している状態で、各ルータで以下のshowコマンドを実行しました。

show ip pim interface
show ip pim neighbor
show ip mroute
show ip mroute count

R1 showコマンドの結果

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R1#show ip pim interface
Address          Interface                Ver/   Nbr    Query  DR     DR
                                          Mode   Count  Intvl  Prior
192.168.1.1      FastEthernet0/0          v2/S   0      30     1      192.168.1.1
192.168.12.1     FastEthernet1/0          v2/S   1      30     1      192.168.12.2
192.168.0.1      Loopback0                v2/S   0      30     1      192.168.0.1
R1#show ip pim neighbor
PIM Neighbor Table
Mode: B - Bidir Capable, DR - Designated Router, N - Default DR Priority,
      S - State Refresh Capable
Neighbor          Interface                Uptime/Expires    Ver   DR
Address                                                            Prio/Mode
192.168.12.2      FastEthernet1/0          02:12:34/00:01:16 v2    1 / DR S
R1#show ip mroute
IP Multicast Routing Table
Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,
       L - Local, P - Pruned, R - RP-bit set, F - Register flag,
       T - SPT-bit set, J - Join SPT, M - MSDP created entry,
       X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
       U - URD, I - Received Source Specific Host Report,
       Z - Multicast Tunnel, z - MDT-data group sender,
       Y - Joined MDT-data group, y - Sending to MDT-data group
Outgoing interface flags: H - Hardware switched, A - Assert winner
 Timers: Uptime/Expires
 Interface state: Interface, Next-Hop or VCD, State/Mode
(*, 239.1.1.1), 00:03:12/stopped, RP 192.168.0.2, flags: SPF
  Incoming interface: FastEthernet1/0, RPF nbr 192.168.12.2
  Outgoing interface list: Null

(192.168.1.100, 239.1.1.1), 00:03:12/00:02:54, flags: PFT
  Incoming interface: FastEthernet0/0, RPF nbr 0.0.0.0
  Outgoing interface list: Null
(*, 224.0.1.40), 02:13:03/00:02:55, RP 0.0.0.0, flags: DCL
  Incoming interface: Null, RPF nbr 0.0.0.0
  Outgoing interface list:
    FastEthernet0/0, Forward/Sparse, 02:13:03/00:02:51

R1#show ip mroute count
IP Multicast Statistics
3 routes using 1474 bytes of memory
2 groups, 0.50 average sources per group
Forwarding Counts: Pkt Count/Pkts(neg(-) = Drops) per second/Avg Pkt Size
/Kilobits per second
Other counts: Total/RPF failed/Other drops(OIF-null, rate-limit etc)
Group: 239.1.1.1, Source count: 1, Packets forwarded: 0, Packets received: 15
  RP-tree: Forwarding: 0/0/0/0, Other: 0/0/0
  Source: 192.168.1.100/32, Forwarding: 0/-1/0/0, Other: 15/0/15
Group: 224.0.1.40, Source count: 0, Packets forwarded: 0, Packets received: 0
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R2 showコマンドの結果

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R2#show ip pim interface

Address          Interface                Ver/   Nbr    Query  DR     DR
                                          Mode   Count  Intvl  Prior
192.168.0.2      Tunnel23                 v2/S   1      30     1      0.0.0.0
192.168.12.2     FastEthernet0/0          v2/S   1      30     1      192.168.12.2
192.168.0.2      Loopback0                v2/S   0      30     1      192.168.0.2
R2#show ip pim neighbor
PIM Neighbor Table
Mode: B - Bidir Capable, DR - Designated Router, N - Default DR Priority,
      S - State Refresh Capable
Neighbor          Interface                Uptime/Expires    Ver   DR
Address                                                            Prio/Mode
192.168.0.3       Tunnel23                 02:13:23/00:01:22 v2    1 / S
192.168.12.1      FastEthernet0/0          02:13:44/00:01:32 v2    1 / S
R2#show ip mroute
IP Multicast Routing Table
Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,
       L - Local, P - Pruned, R - RP-bit set, F - Register flag,
       T - SPT-bit set, J - Join SPT, M - MSDP created entry,
       X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
       U - URD, I - Received Source Specific Host Report,
       Z - Multicast Tunnel, z - MDT-data group sender,
       Y - Joined MDT-data group, y - Sending to MDT-data group
Outgoing interface flags: H - Hardware switched, A - Assert winner
 Timers: Uptime/Expires
 Interface state: Interface, Next-Hop or VCD, State/Mode
(*, 239.1.1.1), 00:04:22/stopped, RP 192.168.0.2, flags: SP
  Incoming interface: Null, RPF nbr 0.0.0.0
  Outgoing interface list: Null

(192.168.1.100, 239.1.1.1), 00:04:22/00:01:29, flags: P
  Incoming interface: FastEthernet0/0, RPF nbr 192.168.12.1
  Outgoing interface list: Null

(*, 224.0.1.40), 02:14:12/00:02:38, RP 0.0.0.0, flags: DCL
  Incoming interface: Null, RPF nbr 0.0.0.0
  Outgoing interface list:
    FastEthernet0/0, Forward/Sparse, 02:14:12/00:02:38< br />R2#show ip mroute count
IP Multicast Statistics
3 routes using 1454 bytes of memory
2 groups, 0.50 average sources per group
Forwarding Counts: Pkt Count/Pkts(neg(-) = Drops) per second/Avg Pkt Size
/Kilobits per second
Other counts: Total/RPF failed/Other drops(OIF-null, rate-limit etc)

Group: 239.1.1.1, Source count: 1, Packets forwarded: 0, Packets received: 0
  RP-tree: Forwarding: 0/0/0/0, Other: 0/0/0
  Source: 192.168.1.100/32, Forwarding: 0/0/0/0, Other: 0/0/0
Group: 224.0.1.40, Source count: 0, Packets forwarded: 0, Packets received: 0
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R3 showコマンドの結果

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R3#show ip pim interface
Address          Interface                Ver/   Nbr    Query  DR     DR
                                          Mode   Count  Intvl  Prior
192.168.0.3      Tunnel23                 v2/S   1      30     1      0.0.0.0
192.168.3.3      FastEthernet1/0          v2/S   0      30     1      192.168.3.3
192.168.0.3      Loopback0                v2/S   0      30     1      192.168.0.3
R3#show ip pim neighbor
PIM Neighbor Table
Mode: B - Bidir Capable, DR - Designated Router, N - Default DR Priority,
      S - State Refresh Capable
Neighbor          Interface                Uptime/Expires    Ver   DR
Address                                                            Prio/Mode
192.168.0.2       Tunnel23                 02:14:28/00:01:43 v2    1 / S
R3#show ip mroute
IP Multicast Routing Table
Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,
       L - Local, P - Pruned, R - RP-bit set, F - Register flag,
       T - SPT-bit set, J - Join SPT, M - MSDP created entry,
       X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
       U - URD, I - Received Source Specific Host Report,
       Z - Multicast Tunnel, z - MDT-data group sender,
       Y - Joined MDT-data group, y - Sending to MDT-data group
Outgoing interface flags: H - Hardware switched, A - Assert winner
 Timers: Uptime/Expires
 Interface state: Interface, Next-Hop or VCD, State/Mode

(*, 239.1.1.1), 00:07:12/00:02:50, RP 192.168.0.2, flags: SJC
  Incoming interface: Null, RPF nbr 0.0.0.0
  Outgoing interface list:
    FastEthernet1/0, Forward/Sparse, 00:07:12/00:02:50

(*, 224.0.1.40), 00:08:09/stopped, RP 0.0.0.0, flags: DCL
  Incoming interface: Null, RPF nbr 0.0.0.0
  Outgoing interface list:
    Tunnel23, Forward/Sparse, 00:08:09/00:00:52

R3#show ip mroute count
IP Multicast Statistics
2 routes using 1308 bytes of memory
2 groups, 0.00 average sources per group
Forwarding Counts: Pkt Count/Pkts(neg(-) = Drops) per second/Avg Pkt Size
/Kilobits per second
Other counts: Total/RPF failed/Other drops(OIF-null, rate-limit etc)

Group: 239.1.1.1, Source count: 0, Packets forwarded: 0, Packets received: 0

Group: 224.0.1.40, Source count: 0, Packets forwarded: 0, Packets received: 0
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問題

• なぜ、Sourceから239.1.1.1のメンバーであるRecieverまでマルチキャストパケットがルーティングされないのですか？
• 正常にマルチキャストパケットをルーティングできるようにするためには、どのように設定すればよいですか？ただし、R2-R3間はトンネルインタフェース上でマルチキャストルーティングを行うものとします。

マルチキャストルーティングの仕組みとCiscoルータでの設定・検証方法を詳しく学びたい方は「詳解IPマルチキャスト」がオススメです。