How to connect a Cisco router behind an MX84?

[Mario]

Hi. I need to connect a Cisco router behind an MX84. The router belongs to another company, so I can't configure or get access to it.
The router has a public IP Address (from my Public IP Addresses Scope) assigned to a WAN interface and I need to connect this interface to one of the ethernet ports on my MX84.
I have been trying to do it but each time I connected the router isn't reachable from outside, even I can't ping the IP address.

Can somebody help me? Please.

[Fruju]

Set a VLAN on the external interface of that router that goes into the MX84 then set that port on the MX84 to have the same VLAN. 

Either that or use ACL's

[PhilipDAth]

I'm going to assume your WAN interface is statically configured, as opposed to PPPoE or something else.

Options include:

1. Get a spare switch, plug your Internet circuit, MX84 WAN interface and the router into it.
2. Use an existing managed switch.  Create a new VLAN.  Put three ports into it in access mode.  Plug your Internet circuit, MX84 WAN interface and the router into it.
3. Ugly.  On your MX create a new VLAN.  Assign it a random subnet your not using.  Put three LAN ports on the MX84 into that VLAN in access mode.  Plug your MX WAN interface into one of these MX84 LAN ports.  Plug your router and Internet circuit into the other two ports.

[PhilipDAth]

I seem to have lost of first reply, so here goes again.  I'm going to assume your MX84 WAN interface is statically addressed rather than using something like PPPoE.

Your options include:

• Get a spare switch.  Plug your Internet circuit, MX WAN port and the router into it.
• Use an existing managed switch.  Created a new VLAN.  Put three ports into it in access mode.  Plug your MX WAN port, Internet circuit and router into it.
• Ugly.  On your MX create a new VLAN.  Assign it a random subnet that is not in use.  Put three LAN ports of your MX into this VLAN in access mode.  Plug your MX WAN port into one of these MX LAN ports.  Plug the Internet circuit and router into the other two ports.