SG350x, layer 2 mode vs layer 3 mode in interface settings

[EnderLiu58018]

Hi everyone

I got a sg305x-24 switch and just cannot figure out what does L2 vs L3 switchport mode do. In other switches you got to toggle L2/L3 for the whole switch before you can do inter-vlan routing. However on the SG350X, the setting is per port. What make things more confusing is even if I leave every port in L2 mode, I can still create IP interface for VLANs and have the switch route between them. What's the real difference between the a port in L2 and L3 mode, because apparently routing still happen when in L2 mode? Do they have different feature or any performance indications?

https://www.cisco.com/c/en/us/support/docs/smb/switches/cisco-350-series-managed-switches/smb5827-configure-vlan-interface-settings-on-a-sx350-sg350x-or-sx550.html

Mentioned this setting but it sounds confusing/not related, it talks about L2/L3 concepts but not the setting itself.

If anyone can help clear this up it would be much appreciated 

[viningele]

I would also like some clarification on this too. Coming from SG300’s to these SG350’s doesn’t make sense. How are supposed to use these features when nothing really explains them, at least there was decent YouTube videos for the SG300 intervlan routing configs.

[viningele]

This video helps a little.

https://youtu.be/ZdEe7cU3x1Q

[JH33Villa]

This is an old response, but if it can help anyone when understanding the SMB line, it is like this:

The 350X/550X series are a bit different from their 300/500 predecessors in the fact that you cannot configure the whole system mode as Layer 2 or 3. The 350X/550X series automatically are Layer 3 by default. This enables the capability of inter-VLAN routing by default. However, you will find that each interface on these switches ARE configurable as Layer 2 or 3. These individual interfaces (physical) are set to Layer 2 so that you can configure each port to tag/untag VLAN's on those ports as most people utilizing switches do this. However, the unique capability of these switches also allow you to configure physical ports as Layer-3 so you can apply ip addresses to those interfaces, effectively making this switch a physical router as well as a VLAN routing device. You will see this when you check the GUI at: IP Configuration --> IPv4 Interface. You will see the physical interfaces you set for Layer3 available to have IP addresses assigned to them alongside the VLAN interfaces now. An absolute awesome feature now with the SMB line. 

I use a SG350X at my branch offices doing this very thing. My ISP has built us a pure Layer-2 network across the Southeast, so I have to make a physical interface IP routable, and route all my local VLAN's through that interface on that switch.