I have following Network Setup:

Basic Home Wifi Router ------------------------------------------------ |

Cisco 2500 Series Wireless Controllers ----------------------------| Cisco SG300-28 POE Switch

2 X Cisco Aironet 2700 Series Access Points --------------------|

From the above, all three: WiFi Router, Wireless Access Point Controller and Access Points are connected to L3 Cisco Switch.

I have a leased line connection with Static Public IP address configured in basic home based wifi router to have internet access.

What I'm trying to do is to eliminate the low end device the Wifi Router in my case which will degrade the performance. Buying a new business router is not an option for time being.

I'm not sure if L3 Switch can do Nating by converting Private IP to Public IP and vice-versa to have internet connection sharing. My only requirement is Internet Connection Sharing without the Router.

I'm curious to know if it's possible to configure Internet Connection settings(ip,subnet,gateway,dns) in L3 Switch(sg300-28) so as to avoid the low end router.

Please anybody confirm if it's possible to share Internet Connection of leased line with L3 Switch without any router.


  • 2
    NAT is a lot more complicated than routing. So it is reasonable to assume that most of the devices which can route packets in hardware won't be able to do NAT in hardware. – kasperd Nov 22 '15 at 19:04
  • 1
    Cisco SG300 simply doesn't support NAT, so you can't use it like that. If you wan't to avoid cheap SOHO router slowing your connection down, put a reasonably modern (not older that 7-8 years) PC between the switch and WAN and install pfSense or OPNsense or any other software router OS. – sam_pan_mariusz Nov 22 '15 at 19:19

The Cisco SG300 does not provide all of the necessary functions of a home router like NAT, DNS relay, or PPPoE. Therefore connecting it directly to a leased line with a single public IP address won't work.

  • Actually, the SG300 does DNS relay, DHCP server, DHCP client, DHCP snooping, Dynamic Arp Inspection, IP Source Guard, DHCPv6 Guard, RA Guard, ND, PVLan, IGMP, VLANs, Layer 3 routing (no RIP/OSPF, and IPv4 only), Port Security, RSTP, PACLs, VLAN ACL access-groups, QoS with DSCP/CoS mappings, 4 outgoing queues, and even 802.1X or MAB port authentication w/VLAN attribute via RADIUS. All at non-blocking full wire speed. But alas, no NAT. All in all these things are pretty awesome for a SOHO switch. – Brain2000 Oct 26 '17 at 15:52
  • Thanks for the correction. The device does indeed sport an impressive feature list, including a DHCP server. (And of course a DHCP client, although the latter seems to be limited to acquiring an IP address for an interface.) I have edited my answer accordingly. I could not find any hint of a DNS relay function or PPPoE though. – Tilman Schmidt Oct 31 '17 at 13:43

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.