CBR40 - Does not pass traffic from an upstream Cisco L3 Switch

[kw0712]

I have my CBR40 connected to a L3 switch with several upstream networks and the CBR40 will not pass the traffic to the Internet.  I have static routes to all the upstream networks and I can ping everything except, anything on the Internet.  The CBR is either dropping the traffic or not performing NAT.

[FURRYe38]

The CBK40 passes traffic from the internet thru its RG6 coax port. There is a built in modem already with in the CBK40 thus this is the interfacing service port to your cable ISP services and to the internet. All other Ports on the back of the CBR40 are LAN side ports. You can place a swich behind (downstream) the CBR40 on one of it's LAN ports, however, this should be a managed switch with IGMP protocols disabled or a non managed switch. 

[kw0712]

I think you misunderstood upstream from downstream. Please see the attached diagram.

[FURRYe38]

So do you get same results with a PC connected directly to the back of the CBR40? 

Have you tried a different switch, something like a non manged switch with a PC behind the switch? 

What is the model# of this Cisco switch? 

You might ask Cisco if there is a certain configuration needed on a Gateway or Router to effect correct traffic transportation with this switch. Possible there is a configuration needed maybe on the CBR40. This is a gateway router configuration. 

[kw0712]

It worked flawless with my xfinty modem/router. The Cisco switch is a 3750 and it is configured correctly. I have been buiding Cisco networks for 20 plus years. 

It is something on the CBR40 ... I believe when a packet hits the CBR40 with a different subnet; then the local LAN subnet it does not know, what to do with the packet.  

[FURRYe38]

Does this happen with out the Cisco switch being on line? 

Possible that there maybe a bug in FW or something that NG didn't intend for the CBR to support or not something most home users are widely using in there configurations. 

@vkdelta 

[vkdelta]

Are the packets VLAN TAGGED when they hit CBR40?

have you configured reverse static routes on the CBR40?