CBS350 with modem Bell "Giga Hub"

[RaphyRaphy]

Hi!

I use the CBS350 switch with several VLANs (intervlan), everything works fine, except I have no internet.
The reason seems to be that I will need to configure the routing of my VLANs on my modem, except that my modem does not seem to be able to do this!

So my question is, what can I do?
According to my research, I would have to add a router which manages the routing of the VLANs, then I put the modem in bridge mode to send it to this router, and finally from the router I will go to my CBS350, would be is that right? Is there really no way to do it just with the equipment I have? And finally, if I really need to add a device, do you have a Cisco device to recommend?

Here is a diagram of my installation to simplify.

Thanks !

[marce1000]

  - Check this thread : https://community.cisco.com/t5/switching/cbs350-what-is-the-recommended-setup-to-share-internet-between/td-p/4196247

 M.

[RaphyRaphy]

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@marce1000  a écrit :

  - Check this thread : https://community.cisco.com/t5/switching/cbs350-what-is-the-recommended-setup-to-share-internet-between/td-p/4196247

 M.

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Yes I had seen this subject, unfortunately the answers given presume that the CBS350 supports NAT, but according to my research this is not the case, so it does not work in my case... it's a shame because I would have really liked the solution of not configuring the modem and for everything to be done at the CBS350 level...

[KJK99]

Switches of the CBS350 class do not support NAT. Also, you will not find a new switch in the CBS350 price range that supports NAT. 

Since CBS350 supports inter-VLAN routing, you do not need a VLAN-aware router. However, you need to be able to set up static routes on your Internet router. Most Internet routers make it possible. Those static routes are necessary to make the Internet router aware about all subnets you set up on the switch.

Bell Giga Hub is not just a modem. It is a modem+Internet router+WiFi access point combo as far as I know. Its Internet router will do NATting, but I'm not sure if you can create static routes on it.

[Richard Burts]

There are several aspects of your issue. But the most important one is that for your network/vlans to have Internet access there must be Network Address Translation. The CBS350 does not support NAT. Perhaps your ISP might agree to translate your traffic toward the Internet? But in my experience that is not very likely. The other option is that you need to obtain some device that does support NAT (and usually that device is a router).

[Giuseppe Larosa]

Hello @RaphyRaphy ,

you would need a router to be inserted between the Bell "giga hub" router and the the multilayer switch CBS350.

BELL <---> NEW Router <---> CBS350 switch

The router will have its "outside" interface connected to the Bell router getting an IP address of the subnet provided by the Bell router.

The router will have one L3 interface to the CBS350 multilayer switch with static routes for the internal subnets.

This router will need to have NAT configured and to translate all the internal networks to its own "outside" so that it can then be natted again by the Bell router.

PAT or or nat overload in cisco terms.

Hope to help

Giuseppe