基于M-LAG组成的双活系统提供了设备级的可靠性，将双归接入的两台设备在逻辑上虚拟成一台设备。M-LAG提供了一个没有环路的二层拓扑同时实现冗余备份。
多级M-LAG互联可以在保证可靠性、提供链路利用率的同时扩展双归接入的网络规模，满足客户的需求。
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第一步【需求分析】
DS1和DS2、AS1和AS2交换机组建了多级M-LAG，DS1和DS2之间Eth-Trunk链路配置Peer-Link，交互M-LAG同步报文。在M-LAG设备之间配置V-STP破除环路。同时，在DS和CS设备上配置OSPF实现三层互通。
M-LAG配置要点：
以AS1和AS2组建M-LAG为例，DS设备配置类似。
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第二步、在AS1和AS2上配置主接口的IP地址，且保证能够三层互通，专门用于M-LAG主备设备间心跳报文的传输。
<AS1> system-view
[~AS1] interface meth 0/0/0
[~AS1-MEth0/0/0] ip address 10.1.1.1 24
[*AS1-MEth0/0/0] quit
---------------------------------------------
<AS2> system-view
[~AS2] interface meth 0/0/0
[~AS2-MEth0/0/0] ip address 10.1.1.2 24
[*AS2-MEth0/0/0] quit
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第三步、在AS1和AS2上配置M-LAG的DFS Group。
[*AS1] dfs-group 1
[*AS1-dfs-group-1] source ip 10.1.1.1
[*AS1-dfs-group-1] priority 150
[*AS1-dfs-group-1] quit
--------------------------------------------
[*AS2] dfs-group 1
[*AS2-dfs-group-1] source ip 10.1.1.2
[*AS2-dfs-group-1] priority 120
[*AS2-dfs-group-1] quit
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第四步、在AS1和AS2上配置M-LAG的Peer-Link
[*AS1] interface eth-trunk 0
[*AS1-Eth-Trunk0] trunkport 10ge 1/0/3
[*AS1-Eth-Trunk0] trunkport 10ge 1/0/4
[*AS1-Eth-Trunk0] mode lacp-static
[*AS1-Eth-Trunk0] peer-link 1
[*AS1-Eth-Trunk0] quit
--------------------------------------------------
[*AS2] interface eth-trunk 0
[*AS2-Eth-Trunk0] trunkport 10ge 1/0/3
[*AS2-Eth-Trunk0] trunkport 10ge 1/0/4
[*AS2-Eth-Trunk0] mode lacp-static
[*AS2-Eth-Trunk0] peer-link 1
[*AS2-Eth-Trunk0] quit
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第五步、在AS1和AS2上配置M-LAG的成员口
[*AS1] vlan batch 11
[*AS1] interface eth-trunk 20
[*AS1-Eth-Trunk20] mode lacp-static
[*AS1-Eth-Trunk20] port link-type trunk
[*AS1-Eth-Trunk20] port trunk allow-pass vlan 11
[*AS1-Eth-Trunk20] trunkport 10ge 1/0/1 to 1/0/2
[*AS1-Eth-Trunk20] dfs-group 1 m-lag 1
[*AS1-Eth-Trunk20] quit
[*AS1] interface eth-trunk 30
[*AS1-Eth-Trunk30] mode lacp-static
[*AS1-Eth-Trunk30] port link-type trunk
[*AS1-Eth-Trunk30] port trunk allow-pass vlan 11
[*AS1-Eth-Trunk30] trunkport 10ge 1/0/5 to 1/0/6
[*AS1-Eth-Trunk30] dfs-group 1 m-lag 2
[*AS1-Eth-Trunk30] quit
[*AS1] commit
--------------------------------------------------------------------
[*AS2] vlan batch 11
[*AS2] interface eth-trunk 20
[*AS2-Eth-Trunk20] mode lacp-static
[*AS2-Eth-Trunk20] port link-type trunk
[*AS2-Eth-Trunk20] port trunk allow-pass vlan 11
[*AS2-Eth-Trunk20] trunkport 10ge 1/0/1 to 1/0/2
[*AS2-Eth-Trunk20] dfs-group 1 m-lag 1
[*AS2-Eth-Trunk20] quit
[*AS2] interface eth-trunk 30
[*AS2-Eth-Trunk30] mode lacp-static
[*AS2-Eth-Trunk30] port link-type trunk
[*AS2-Eth-Trunk30] port trunk allow-pass vlan 11
[*AS2-Eth-Trunk30] trunkport 10ge 1/0/5 to 1/0/6
[*AS2-Eth-Trunk30] dfs-group 1 m-lag 2
[*AS2-Eth-Trunk30] quit
[*AS2] commit
END
原作者：Ricky
