Connecting Cisco CBS350 to Internet Modem

[EverBlueSky]

Hello,

I need to use this L3-capable switch to connect servers to the Internet. The ISP did not supply a router.

FYI: CBS350 does not support NAT. I have read that inside devices can find the Internet with a static route.

CBS350 routing is enabled.

DHCP is enabled. The Pool for inside devices has been configured.

QUESTIONS:

Do I set up two VLANs? One VLAN configued for inside devices with the above pool addresses, and say another VLAN for the connection to the IPS-provided modem, with the VLAN interface configured with the ISP-provided IP/SN/GW?

Does the VLAN on the ISP side need to be the default VLAN?

What would the static route be, 0.0.0.0/0 or one with the ISP WAN IP?

Any help is appreciated. Thank you.

[Flavio Miranda]

@EverBlueSky 

 You can not achive this using a CBS350. It is not enouth to support routing, NAT is required. Thats why a router is required. 

When you send you traffic to the ISP with your internal VLANs. the ISP will refuse to reply to you because they dont know your internal subnet. 

Thats why NAT is required. When the NAT take place, the IP address that will get to the ISP is the Modem IP address and for that they know how to reply. 

[EverBlueSky]

Thanks Flavio. So what does routing on the L3 switch provide?

[Flavio Miranda]

Routing. L3 = routing. 

 In a scenario where you have a router with NAT connected to ISP, you can use the L3 switch to configure your vlans and route the traffic to your router. And then your router will do the NAT and send the traffic to ISP

[EverBlueSky]

So can a 9300 function as the router... do the NAT and connect to the IPS modem? The circuit is terminated at a modem only. All of the inside routing/switching is up to us to configure.

[Flavio Miranda]

It does. With proper license

Configure and Verify NAT on Catalyst 9000 Switches - Cisco

[EverBlueSky]

Any other Cisco at a lower price point? This is not an enterprise-critical circuit.

[Flavio Miranda · Accepted solution]

Its been a problem recommend cisco hardware because they change all the time. But, you can take a look in the routers for small office RV345, RV340 , etc

[EverBlueSky]

Thanks for your help, Flavio.