Switching – Best Practice for Connecting 3 Switches to Router

cablingrouterswitchswitching

I am wondering the best way to connect 3 switches to a router in a server rack.

The router is a Cisco RV320 (Dual Gigabit with two static IPs) There is three 48-port Ubiquiti EdgeSwitches, A Datto backup appliance, a Lenovo Thinkserver with 2 VMs running a domain controller and file share, a PBX, and a NVR security camera appliance and patch panels for the office computers.

In total there’s about 140 client devices including devices connected to three Unifi Pro Acces Points (which are connected to the switches) and all the phones.

How should all of these interconnect? Should they be daisy chained and then connect just one switch to the router? Is there a benefit to connecting switch-to-switch with more than one cable? Is there a benefit to connecting each switch to its own port on the router, but also connecting the switches to one another?

Best Answer

Daisy chaining generally is not a good idea. Any problem with an intermediate switch will cause problems across the network. Additionally, security zoning with VLANs will get awkward at best.

Best practice is to select a 'core' switch you connect all other switches and infrastructure devices to. Your router isn't well equipped as a core device with just two GE ports.

If you need more bandwidtch between core and edge switch you can connect more than one link, provided you configure an aggregation group (LAG) for these ports on both sides (preferrably using LACP) - do not connect multiple links without configuring LAG or spanning tree.

Running redundant connections between edge switches creates a physical mesh. This in turn requires you to configure spanning tree: select the core switch as root bridge and set it to a very low STP priority (0). The redundant links won't be used for traffic in normal use but they'll kick in automatically when an active link is disconnected.