目  錄

1 組播VLAN······································································································································ 1-1

1.1 組播VLAN簡介······················································································································· 1-1

1.2 組播VLAN配置任務簡介·········································································································· 1-2

1.3 配置組播VLAN························································································································ 1-2

1.3.1 配置準備······················································································································· 1-2

1.3.2 配置組播VLAN·············································································································· 1-3

1.4 配置組播VLAN內IGMP Snooping轉發表項的最大數量····························································· 1-3

1.5 組播VLAN顯示和維護············································································································· 1-4

1.6 組播VLAN典型配置舉例·········································································································· 1-4

1 組播VLAN

1.1  組播VLAN簡介

如圖1-1所示，在傳統的組播點播方式下，當屬於不同VLAN的主機Host A、Host B和Host C同時點播同一組播組時，三層設備（Router A）需要把組播數據在每個用戶VLAN（即主機所屬的VLAN）內都複製一份發送給二層設備（Switch A）。這樣既造成了帶寬的浪費，也給三層設備增加了額外的負擔。

圖1-1 未運行組播VLAN時的組播數據傳輸

可以使用組播VLAN功能解決這個問題。在二層設備上配置了組播VLAN後，三層設備隻需把組播數據在組播VLAN內複製一份發送給二層設備，而不必在每個用戶VLAN內都複製一份，從而節省了網絡帶寬，也減輕了三層設備的負擔。

目前設備隻支持基於子VLAN的組播VLAN：

如圖1-2所示，接收者主機Host A、Host B和Host C分屬不同的用戶VLAN。在Switch A上配置VLAN 10為組播VLAN，將所有的用戶VLAN都配置為該組播VLAN的子VLAN，並在組播VLAN內使能IGMP Snooping。

圖1-2 基於子VLAN的組播VLAN示意圖

配置完成後，IGMP Snooping將在組播VLAN中對路由器端口進行維護，而在各子VLAN中對成員端口進行維護。這樣，Router A隻需把組播數據在組播VLAN內複製一份發送給Switch A即可，Switch A會將其分發給該組播VLAN內那些有接收者的子VLAN。

1.2  組播VLAN配置任務簡介

表1-1 組播VLAN配置任務簡介

1.3  配置組播VLAN

1.3.1  配置準備

在配置組播VLAN之前，需完成以下任務：

·     創建相應的VLAN

·     在欲配置為組播VLAN的VLAN內使能IGMP Snooping

1.3.2  配置組播VLAN

首先需要把某個VLAN配置為組播VLAN，再將用戶VLAN添加到該組播VLAN內，使其成為組播VLAN的子VLAN。

表1-2 配置基於子VLAN的組播VLAN

1.4  配置組播VLAN內IGMP Snooping轉發表項的最大數量

用戶可以調整組播VLAN內IGMP Snooping轉發表項的最大數量，當所有組播VLAN內維護的表項總數達到最大數量後，將不再創建新的表項，直至有表項被老化或被手工刪除。

表1-3 配置組播VLAN內IGMP Snooping轉發表項的最大數量

1.5  組播VLAN顯示和維護

在完成上述配置後，在任意視圖下執行display命令可以顯示配置後組播VLAN的運行情況，通過查看顯示信息驗證配置的效果。

表1-4 組播VLAN顯示和維護

1.6  組播VLAN典型配置舉例

1. 組網需求

·     如圖1-3所示，Router A通過接口GigabitEthernet3/0/1連接組播源（Source），通過接口GigabitEthernet3/0/2連接Switch A；Router A上運行IGMPv2，Switch A～Switch C上都運行版本2的IGMP Snooping，並由Router A充當IGMP查詢器。

·     組播源向組播組224.1.1.1發送組播數據，Host A～Host D都是該組播組的接收者（Receiver），且分別屬於VLAN 2～VLAN 5。

·     通過在Switch A上配置基於子VLAN的組播VLAN，使Router A通過組播VLAN向Switch A下分屬不同用戶VLAN的主機分發組播數據。

2. 組網圖

圖1-3 基於子VLAN的組播VLAN配置組網圖

3. 配置步驟

配置IP地址

請按照圖1-3配置各接口的IP地址和子網掩碼，具體配置過程略。

配置Router A

# 使能IP組播路由，在各三層接口上使能PIM-DM，並在主機側接口GigabitEthernet3/0/2上使能IGMP。

<RouterA> system-view

[RouterA] multicast routing-enable

[RouterA] interface Gigabitethernet 3/0/1

[RouterA-GigabitEthernet3/0/1]port link-mode route

[RouterA-GigabitEthernet3/0/1] pim dm

[RouterA-GigabitEthernet3/0/1] quit

[RouterA] interface GigabitEthernet 3/0/2

[RouterA-GigabitEthernet3/0/2]port link-mode route

[RouterA-GigabitEthernet3/0/2] pim dm

[RouterA-GigabitEthernet3/0/2] igmp enable

配置Switch A

# 全局使能IGMP Snooping。

<SwitchA> system-view

[SwitchA] igmp-snooping

[SwitchA-igmp-snooping] quit

# 創建VLAN 2～VLAN 5。

[SwitchA] vlan 2 to 5

# 配置端口GigabitEthernet3/0/2為Trunk端口，並允許VLAN 2和VLAN 3通過。

[SwitchA] interface GigabitEthernet 3/0/2

[SwitchA-GigabitEthernet3/0/2] port link-type trunk

[SwitchA-GigabitEthernet3/0/2] port trunk permit vlan 2 3

[SwitchA-GigabitEthernet3/0/2] quit

# 配置端口GigabitEthernet3/0/3為Trunk端口，並允許VLAN 4和VLAN 5通過。

[SwitchA] interface GigabitEthernet 3/0/3

[SwitchA-GigabitEthernet3/0/3] port link-type trunk

[SwitchA-GigabitEthernet3/0/3] port trunk permit vlan 4 5

[SwitchA-GigabitEthernet3/0/3] quit

# 創建VLAN 10，把端口GigabitEthernet3/0/1添加到該VLAN中，並在該VLAN內使能IGMP Snooping。

[SwitchA] vlan 10

[SwitchA-vlan10] port GigabitEthernet 3/0/1

[SwitchA-vlan10] igmp-snooping enable

[SwitchA-vlan10] quit

# 配置VLAN 10為組播VLAN，並把VLAN 2～VLAN 5都配置為該組播VLAN的子VLAN。

[SwitchA] multicast-vlan 10

[SwitchA-mvlan-10] subvlan 2 to 5

[SwitchA-mvlan-10] quit

配置Switch B

# 全局使能IGMP Snooping。

<SwitchB> system-view

[SwitchB] igmp-snooping

[SwitchB-igmp-snooping] quit

# 創建VLAN 2，把端口GigabitEthernet3/0/2添加到該VLAN中，並在該VLAN內使能IGMP Snooping。

[SwitchB] vlan 2

[SwitchB-vlan2] port GigabitEthernet 3/0/2

[SwitchB-vlan2] igmp-snooping enable

[SwitchB-vlan2] quit

# 創建VLAN 3，把端口GigabitEthernet3/0/3添加到該VLAN中，並在該VLAN內使能IGMP Snooping。

[SwitchB] vlan 3

[SwitchB-vlan3] port GigabitEthernet 3/0/3

[SwitchB-vlan3] igmp-snooping enable

[SwitchB-vlan3] quit

# 配置端口GigabitEthernet3/0/1為Trunk端口，並允許VLAN 2和VLAN 3通過。

[SwitchB] interface GigabitEthernet 3/0/1

[SwitchB-GigabitEthernet3/0/1] port link-type trunk

[SwitchB-GigabitEthernet3/0/1] port trunk permit vlan 2 3

配置Switch C

Switch C的配置與Switch B相似，配置過程略。

檢驗配置效果

# 查看Switch A上所有組播VLAN的信息。

[SwitchA] display multicast-vlan

 Total 1 multicast-vlan(s)

 Multicast vlan 10

   subvlan list:

    vlan 2-5

# 查看Switch A上IGMP Snooping組播組的信息。

[SwitchA] display igmp-snooping group

  Total 5 IP Group(s).

  Total 5 IP Source(s).

  Total 5 MAC Group(s).

  Port flags: D-Dynamic port, S-Static port, C-Copy port, P-PIM port

  Subvlan flags: R-Real VLAN, C-Copy VLAN

  Vlan(id):2.

    Total 1 IP Group(s).

    Total 1 IP Source(s).

    Total 1 MAC Group(s).

    Router port(s):total 0 port(s).

    IP group(s):the following ip group(s) match to one mac group.

      IP group address:224.1.1.1

        (0.0.0.0, 224.1.1.1):

          Host port(s):total 1 port(s).

            GE3/0/2                (D)

    MAC group(s):

      MAC group address:0100-5e01-0101

          Host port(s):total 1 port(s).

            GE3/0/2

  Vlan(id):3.

    Total 1 IP Group(s).

    Total 1 IP Source(s).

    Total 1 MAC Group(s).

    Router port(s):total 0 port(s).

    IP group(s):the following ip group(s) match to one mac group.

      IP group address:224.1.1.1

        (0.0.0.0, 224.1.1.1):

          Host port(s):total 1 port(s).

            GE3/0/2                (D)

    MAC group(s):

      MAC group address:0100-5e01-0101

          Host port(s):total 1 port(s).

            GE3/0/2

  Vlan(id):4.

    Total 1 IP Group(s).

    Total 1 IP Source(s).

    Total 1 MAC Group(s).

    Router port(s):total 0 port(s).

    IP group(s):the following ip group(s) match to one mac group.

      IP group address:224.1.1.1

        (0.0.0.0, 224.1.1.1):

          Host port(s):total 1 port(s).

            GE3/0/3                (D)

    MAC group(s):

      MAC group address:0100-5e01-0101

          Host port(s):total 1 port(s).

            GE3/0/3

  Vlan(id):5.

    Total 1 IP Group(s).

    Total 1 IP Source(s).

    Total 1 MAC Group(s).

    Router port(s):total 0 port(s).

    IP group(s):the following ip group(s) match to one mac group.

      IP group address:224.1.1.1

        (0.0.0.0, 224.1.1.1):

          Host port(s):total 1 port(s).

            GE3/0/3                (D)

    MAC group(s):

      MAC group address:0100-5e01-0101

          Host port(s):total 1 port(s).

            GE3/0/3

  Vlan(id):10.

    Total 1 IP Group(s).

    Total 1 IP Source(s).

    Total 1 MAC Group(s).

    Router port(s):total 1 port(s).

            GE3/0/1                (D)

    IP group(s):the following ip group(s) match to one mac group.

      IP group address:224.1.1.1

        (0.0.0.0, 224.1.1.1):

          Host port(s):total 0 port(s).

    MAC group(s):

      MAC group address:0100-5e01-0101

          Host port(s):total 0 port(s).

由此可見，IGMP Snooping在組播VLAN（VLAN 10）中維護路由器端口，而在各子VLAN（VLAN 2～VLAN 5）中維護各自的成員端口。