Vlan network at present, the processing of an external network (192.168.20.0/24) by only one vlan interface in a bridge-domain(BD for short), a BD corresponds to a loop, when the external network for the first router (gateway 192.168.20.5 on loop), when again for a second router (gateway 192.169.20.10 will be bound to the local0), while the second router is used for forwarding the gateway or (192.168.20.5), this leads to a problem is,Multiple routers cannot independently turn on and off THE SNAT function, and the source IP of the message sent by the second router is not its own gateway (192.169.20.10).What do you do with this?

1. Can a VLAN subinterface be bound to multiple bridge-domains and simultaneously copy messages to multiple bound Bridge-domains?

2. Or can we make a BD have multiple loops of gateways that can be bound to the network segment?

3, or by other means of implementation?