Cannot ping router interface from switch

[aldentel]

I have a Cisco C921 I am trying to set up as a secondary router. 

I have int g4 connected to the LAN with a 10.20.x.x network

Int g5 is connected to the fiber ring with a 10.15.x.x network.

There are two other routers on the fiber ring. The difference is that this router is on the same subnet (10.20.x.x) as one of the other routers (which is primary) and will not be supplying dhcp. 

From a PC connected to an L2 switch that is directly connected to the router, I can ping the router on g4, but not on g5 and I cannot get out to the other router or the internet. The path to the internet is through that primary router.

I have set a static route to the firewall on the same network connected to the primary router.

I am hoping I have just missed something obvious! New to setting up routers!

[Martin L]

First of all check if PC has a default gateway (IP of 10.20.x.x = secondary router); if the topology is PC<>L2 switch<>Secondary router <> Primary router<>Internet, where is firewall? Can u reach Internet from both routers? Router do know about their directly connected networks (show ip route) but not about any remote networks; Enable routing protocol or add Static routes.  

To reach Internet, you need a default route on routers; Since there is one way out to the Net, add ip route 0.0.0.0 0.0.0.0 exit-interface-# on Secondary router and on Primary as well. 

do a trace 8.8.8.8 from PC to see how far u can reach. 

Regards, ML
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[aldentel]

Hi Martin,

The first problem was in fact that I needed to put the default gateway of my secondary router in the configs for the PC. I am now at least able to ping g4 and g5 and the local network. I cannot ping anything that is not directly connected.I still cannot get out to the internet.

All 3 routers have default IP routes to the Firewall as their path to the internet. The setup at the primary router and where the firewall is, is a router on a stick. When I trace 8.8.8.8 it only gets as far as my secondary router.

I really think my issue is that I cannot use the same subnet as the primary for this location, possibly due to the way the fiber ring is set up. It is managed by the ISP. I am guessing I need to build out a separate subnet (10.0.x.x for example) and supply dhcp locally. Both other routers have a domain controller that is supplying dhcp locally. This is a production environment so other locations are getting to the internet no prob. Is there a way to make this work without rebuilding out that entire location? I have an alternate way currently supplying internet to this location but the fiber ring has a much higher bandwidth so want to make this work!

Thanks! Ann