Netgear AC1750 and Cisco 3750 issues with internet connectivity

[fireypickle8918]

I am having trouble getting from VLAN out to the internet.

I have a Netgear AC1750 with LAN IP address of 192.168.1.1.

Connected to one of the LAN ports, I have a Cisco 3750 switch configured with two VLANs and utilizing the layer 3 functionality.

• VLAN30, SVI gateway 10.1.30.1
• VLAN40, SVI gateway 10.1.40.1

I can ping the gateways and can communicate between VLANs. I can even ping the router (192.168.1.1) from each VLAN. 

However, I cannot ping any external internet address from any VLAN devices. Is this an issue with the R6700v2 routing or my switch config?

[Giuseppe Larosa]

Hello,

you need to change the configuration of the netgear router in order to :

a) have static routes for networks behind the C3750

In Cisco CLI would be

ip route 10.1.30.0 255.255.255.0 192.168.1.2

ip route 10.1.40.0 255.255.255.0 192.168.1.2

(note I supposed that C3750 IP address is 192.168.1.2 change it with the effective IP address)

I have also supposed that the network masks for networks are /24 = 255.255.255.0

b) you need to extend the NAT configuration so that IP sources of 192.168.1.0/24 and IP sources of networks behind the switch 10.1.30.0/24 and 10.1.40.0/24 are translated. The current configuration of the NAT on the netgear supports only the directly connected internal LAN 192.168.1.0/24.

NAT is not supported on C3750 you cannot configure it on the switch.

For reference on how to configure the netgear router see the following links:

http://www.downloads.netgear.com/files/GDC/R6400/R6400_UM_11jun32015.pdf

pag 140

ADVANCED > Advanced Setup > Static Routes.

I couldn't find a section about NAT. But it is mentioned in the section about port forwarding.

You will use a web browser as the router provides a web based GUI

Edit:

also the C3750 requires configuration for inter vlan routing and for setting the default route:

ip routing

ip route 0.0.0.0 0.0.0.0 192.168.1.1

Edit2:

A way to extend the NAT operation on the netgear could be that of flagging the private check box when configuring the static route. This is only my guess. The guide says only that setting this flag avoids the static route to be advertised in RIP, but it might also enable NAT for source addresses belonging to the destination described in the static route.

It makes sense as there isn't a specific NAT configuration page in the guide.

Hope to help

Giuseppe

[fireypickle8918]

Hi, thanks for the response.

I believe I have configured the switch correctly. Config here: https://pastebin.com/QqekDaPf

On the Netgear, I have tried creating static routes with "Private" mode checked and unchecked with no luck.

Netgear static route screenshot (192.168.1.10 is the interface on the Cisco switch): 

[Giuseppe Larosa]

Hello,

about the switch configuration have you issued no shut under SVI interfaces Vlan30 and Vlan40 ?

If so you are fine. Also the static default route is correct.

Just to understand if the static routes on the netgear are working can you ping 192.168.1.1 on netgear starting from a host in network 10.1.30.0/24 or 10.1.40.0/24 ?

If so routing is OK and the only part to be solved is how to extend NAT on the NETGEAR.

You have written that you have tried with and without the private checkbox set with no changes in behaviour.

However, it is important to verify that the routing section is now fine as explained above.

May you report the results of the ping tests I have proposed above ?

Hope to help

Giuseppe

[fireypickle8918]

Yes, I can ping the Netgear (192.168.1.1) from a device on VLAN30 (10.1.30.2). I suppose that the Netgear is not capable of NATing like I want.

[Giuseppe Larosa]

Hello,

so the routing configuration is fine.

>> I suppose that the Netgear is not capable of NATing like I want. 

The real issue is that the router GUI is missing a dedicated page for NAT settings.

It is strange, because the router supports static routes and even RIP, so it should take care of NAT also for not directly connected subnets. But there is no easy way to enable this.

Hope to help

Giuseppe

[fireypickle8918]

I looked around for RIP settings and it looks like the RIP Direction is set to Both (In and Out) and the RIP version setting is set to "Disabled". Could this be the issue?

Thanks so much for your help.

[Giuseppe Larosa]

Hello,

unfortunately enabling RIP should not make any difference as it is only a routing protocol.

As I wrote before a NAT configuration web page is missing on the router GUI.

At this point I would expect one option to enable NAT for static routes in the static routes web page, but you have tried the private option with no success.

However, you can try to enable RIP it shouldn't cause problems.

Hope to help

Giuseppe