One-armed without Core Switch

[kima25]

Hello, 

In the case where a MX One-Armed is connected to a MX Spoke, and dynamic routing is required for voice traffic through the MX One-Armed, would a Layer 3 switch be necessary?

Thank you.

[GIdenJoe · Accepted solution]

It depends on your setup.

At the one armed concentrator you still need an upstream router/firewall for internet or WAN connectivity.
If the servers you need to reach are in the same subnet as the MX concentrator then the MX can directly reach those devices although it is not best practice.  It is better that the one armed concentrator lives in it's own mini subnet and the upstream router/switch/firewall routes towards the server.

At the spoke you can have that MX be the router of all the local subnets there.

If you want more depth information it would be great if you added some more details about your setup though.

[PhilipDAth]

It doesn't have to be a switch - but it does have to be some kind of layer 3 device.  Because you said you are using a dynamic routing protocol - you must already have this.