Setting up intervlan routing and default route to internet on Catalyst 3750

Evening all.

I have set up a stack of 3750 G's to act as a vlan router.  I am able to successfully ping within the vlans from all switches.  I can also ping the next hop (a firewall interface) from the 3750 stack but not from the other switches or connected devices within the local network.

When reviewing the documentation on Cisco's site for this I found a missing point (to input the ip routing command) which resolved my initial issue of not being able to route at all between the vlans themselves.  I'm here at the house tonight and thinking about this issue and wonder if any of you can answer the following -

I have default gateways set up on each of the extended 3750's but not on the routing 3750.

-  Do I need to set up a DG on the routing 3750?
-  If so, could this be the core problem with not be able to route from internal devices out the default route?
-  If not or other, could anyone share with me what I may be missing/need to add?

I have run the following shows where appropriate on the network with expected returns -

show vlan - all vlans show up on each device
show vtp stat - device status displaying correctly and correct dB versions showing
show ip route   (routing 3750) - all vlans showing as (C)onnected and default route 0.0.0.0 0.0.0.0 x.x.x.x (S)tatic

No routing protocol is in use and only static route is the default pointing to the inside interface of the firewall.

Thanks for your insight folks!
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atlas_shudderedSr. Network EngineerAsked:
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Don JohnstonConnect With a Mentor InstructorCommented:
>Do I need to set up a DG on the routing 3750?
No. DG's are for devices that can't route. Like end stations and layer 2 switches.

>If so, could this be the core problem with not be able to route from internal devices out the default route?
No. Most likely the problem is the device you're pointing to for your default route doesn't have a path (route) back to the networks connected to the 3750. The default route sends traffic out, but the device you're sending it to needs to know about the network the traffic originated from.

>If not or other, could anyone share with me what I may be missing/need to add?
Go to the device this is handling the default route traffic and create static routes for the 3750 connected networks and use the 3750 as the next hop address.

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bluepetCommented:
Agree with donjohnston, did you configure route back to the VLANs at the firewall?

it is possible that your routing-3750 sends the icmp to the firewall, if there is no route at firewall back to the VLAN network, the firewall might drop it or send it to where the default route is pointing to.

Another reason could be your firewall is blocking/dropping ICMP which is a default rule on most firewall. You might want to check your firewall rule and add a temporary rule to allow your firewall interfaces to be ping for testing purpose.
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atlas_shudderedSr. Network EngineerAuthor Commented:
Thanks for the input donj.  I went back and checked and had indeed missed the DG.  Its all about the details...

Thanks again
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