Motorola NVG510 "Cascaded Router"

Contributor

Motorola NVG510 "Cascaded Router"

[ Edited ]

Can somebody explain the "Cascaded Router" configuration for the NVG510? I.e., what problem does using it solve? What's a typical set-up (including the IP addresses of devices on one's network)?

 

See screen shot:

 

 

 

The software version of the NVG510 is 9.0.6h2d30.

Message 1 of 14 (22,545 Views)
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Accepted by SomeJoe7777 (Expert)
‎09-30-2015 1:39 AM

Re: Motorola NVG510 "Cascaded Router"

Cascaded router option is only useful if you've purchased static IP addresses. It lets you tell the gateway that the static IP addresses are reachable via your own router, thus the static IP addresses can be on the other side of your own router.

It is equivalent to inserting a static route into the gateway.

Message 2 of 14 (22,479 Views)
Contributor

Re: Motorola NVG510 "Cascaded Router"

Can you elaborate?

Message 3 of 14 (21,500 Views)
Tutor

Re: Motorola NVG510 "Cascaded Router"


walkerbread wrote:

Can you elaborate?


No offense, but if you don't understand what SomeJoe wrote here:

"It is equivalent to inserting a static route into the gateway."

 

...then you probably don't need to use Cascaded Router. You probably want to use IP Passthrough for normal router-behind-NVG510 situations... see this post for more info.

Message 4 of 14 (21,099 Views)
Tutor

Re: Motorola NVG510 "Cascaded Router"

I have a block of 14 usable static IP addresses and I'm trying to configure my own third party router to allocate and route the static IP addresses.
I've put the correct configuration information in the cascaded router dialoges, and I'm unsure of where my configuration problem is. I can't view the routing table for the NVG510 nor can I see any traffic sent from a computer connected to the NVG510 to an IP address allocated to the cascaded router when I tcpdump the cascaded router.

I don't understand your statement "It is equivalent to inserting a static route into the gateway" and an IP passthrough is NOT what I need.

Please elaborate.

Message 5 of 14 (16,100 Views)
ACE - Expert

Re: Motorola NVG510 "Cascaded Router"


NaruFGT wrote:

...

I don't understand your statement "It is equivalent to inserting a static route into the gateway" and an IP passthrough is NOT what I need.

Please elaborate.


It means that filling in the RG's cascaded router form and submitting it basically creates a static routing rule to route the static subnet to the target cascaded router's IP address.  That router is then responsible for knowing how to get to the destination IP addresses, and knowing to route the traffic from those hosts back to the RG.

This is different from what IP Passthrough does, which takes the single dynamic public IP address and passes it through to the router in the IP Passthrough zone when it makes a DHCP request.  It also passes all unsolicited traffic to that single dynamic public IP address that passes any enabled filters, and is not otherwise directed via port forwaring rules, to that router.

*The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.
Message 6 of 14 (16,067 Views)
Contributor

Re: Motorola NVG510 "Cascaded Router"

Ok, I understand the static route reference but I'm unsure of the settings for the Cascaded Router and I can find zero instructions for their use online.  I'll take a stab, please let me know if I'm on track.  I have a static block of IPs, xxx.xxx.xxx.1-8 and I want to use one of my assignable IPs for the interface of my router so I can reach it from outside (a backdoor into my network should my primary WAN fail).  My best guess for this config would be:

 

Cascaded Router Address: xxx.xxx.xxx.2 (my first assignable address)

Network Address: xxx.xxx.xxx.1

Subnet Mask: 255.255.255.248

 

Router Interface (static assignment)

IP Address: xxx.xxx.xxx.2

Subnet Mask: 255.255.255.248

Gateway: xxx.xxx.xxx.7

 

So then I should be able to use my router to assign xxx.xxx.xxx.3-6, correct?

Message 7 of 14 (13,760 Views)
ACE - Expert

Re: Motorola NVG510 "Cascaded Router"

[ Edited ]

@JustAGeek 

 

When configuring a Cascaded Router, it is my understanding that it should have an IP address within the LAN the RG controls.  So... let's say you have your RG at 192.168.1.254, with its LAN at 192.168.1.0/24, you could put your Cascaded Router's WAN address at, say, 192.168.1.10 (maybe via static assignment in your router, or maybe via directed DHCP assignment).

 

Cascaded Router Address: 192.168.1.10

Network Address: xxx.xxx.xxx.0

Subnet Mask: 255.255.255.248

 

Then what happens is that your router will receive all traffic for that subnet.  Use DHCP or static assignment to give the devices on your router's LAN IP addresses in your public subnet (i.e. they are not addressed by NATted private addresses, they hold the actual public address).

 

Does that make sense?

 

*The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.
Message 8 of 14 (13,710 Views)
Contributor

Re: Motorola NVG510 "Cascaded Router"

[ Edited ]
So - it seems that a very important part of this configuration is the change of subnet address from the ATT router's private subnet (typically /24) to the router's WAN interface where in your example you give it 192.168.1.10/29 to match the allocated block of eight addresses. So, the ATT router will be forwarding some /29 packets with a completely different start (like 162.24.15.X) to the 192.168.1.10 interface of the router, and it will then decode those and route them provided you have the proper static routes defined.

But here's the problem: I (will tomorrow) have a Cisco RV325 and it won't let me static route network packets that are not in the range of the WAN IP network. The routes must have an address that exists within the range of the WAN interface. If the Cisco allowed me to define alias addresses for the WAN port like my Netgear UTM did, this would work fine. I did get this working on an Asus RT3200 running the Merlin WRT firmware using IP aliasing and some convoluted NAT, but it isn't stable enough so now I'm hoping an industry standard Cisco solution should work better. However, it seems that both options on this ATT router for static IPs present problems - the "public subnet" creates double NAT problems and this "cascaded router" without ability to assign a public WAN router address is not standard routing procedure (JustAGeek's proposed configuration is standard, this is not).

I am wondering if this will work, which IIUC is what you suggested: let the Cisco route the public IP addressed packets to a private VLAN with the public network address? Maybe the router will automatically setup the correct routes and deal with packets hitting the 192.168.1.10/29 address? In that case, what "default gateway" IP address do I use to configure the private VLAN on the Cisco? So for instance, if the private VLAN is 162.24.15/29 should it's default gateway be 192.168.1.10 (the WAN address) on the Cisco? Normally this default gateway adress must be on the same subnet as the VLAN, so I can imagine this not working correctly - another manifestation of this strange cascaded router option...

Any suggestions?
Message 9 of 14 (6,648 Views)
ACE - Expert

Re: Motorola NVG510 "Cascaded Router"

[ Edited ]

That's not my understanding:

 

You have the Gateway accepting two different address ranges on the WAN side, the public dynamic and the public static.  It handles one internal LAN of 192.168.1.0/24.

 

Your cacaded router acquires some WAN-side address on the 192.168.1.0/24 subnet, either via static assignment or DHCP (if by static assignment, it should be outside the DHCP range).  All traffic between the two will be on this subnet.

 

On the cascaded router's LAN side, it should be running the public static IP range.  It can hand it out via DHCP or you can manually statically configure them.

 

The gateway will set up a static route forwarding all traffic to the public static subnet to your cascaded router and will not be preforming NAT for this traffic, i.e the addresses in the header remain intact.  In this configuration, your cascaded router should also not be performing NAT as it should be passing the IP addressess in the header untouched..

 

The Gateway will continue to perform NAT between the public dynamic address and the other private IP addresses on the LAN not assigned to the cascaded router.

 

 

 

*The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.
Message 10 of 14 (6,175 Views)
Contributor

Re: Motorola NVG510 "Cascaded Router"

[ Edited ]
Your and my suggested configurations are the same IIUC: the cascaded router will have only one IP on the WAN interface, and that WAN IP will be in the private subnet range of the ATT gateway. The cascaded router will configure one VLAN with the public address network, which will result in static routes that will carry packets received on the WAN interface having the VLAN's network address to that VLAN.

That does leave one final question: what is the default route for the internal hosts using the public network IP addresses? In other words, say I have an internal host with public IP 162.25.14.4 on the cascaded router's VLAN serving 162.25.15.0/29 - what should that host use as it's router IP? If there's no IP on that subnet configured inside the cascaded router, then that subnet can't route back through to the gateway and onward IIUC, which leads back to the original problem of not being able to assign one of the public IP addresses to the router as one would *normally* do. And since Cisco doesn't support aliasing or even IOS's "secondary IP" on these devices, it seems we're back at square one. The router needs to be addressable on the public network in order for hosts on that network to be able to route outbound packets to it...
Message 11 of 14 (6,037 Views)
ACE - Expert

Re: Motorola NVG510 "Cascaded Router"

Your internal router should be configured to have the router address (the lowest odd-numbered address) on its LAN side:

 

.0 unused

.1 your router's address

.2-.6 usable by your devices

.7 broadcast

 

Your router's address should be the default gateway.

 

*The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.
Message 12 of 14 (5,847 Views)
Contributor

Re: Motorola NVG510 "Cascaded Router"

@JefferMC

Yep! When I got the Cisco RV325 router ($210 on Amazon BTW) it let me configure a subnet on a LAN port on which I could allocate an IP. I set up that subnet to my public subnet address and gave the port the subnet gateway address per your suggestion, allowed the ports in the firewall and it all works like a charm!

Incidentally, it was necessary to set up the router's WAN port with the same subnet mask as the public IP range. If you use the typical /24 mask of the ATT gateway's private subnet then packets destined for the public IP range are masked out at your router's WAN port. In my case, I had a /29 public network so I set up the private subnet on the ATT gateway to 192.168.2.247/29 (mask 255.255.255.248) and gave the ATT gateway the IP: 192.168.2.254 and my router's WAN port: 192.168.2.253. This was the key to making it work, as when the WAN port was masked with /24 it failed to route the packets into the router.
Message 13 of 14 (5,714 Views)
ACE - Expert

Re: Motorola NVG510 "Cascaded Router"


NoTarget wrote:
...
Incidentally, it was necessary to set up the router's WAN port with the same subnet mask as the public IP range. If you use the typical /24 mask of the ATT gateway's private subnet then packets destined for the public IP range are masked out at your router's WAN port. In my case, I had a /29 public network so I set up the private subnet on the ATT gateway to 192.168.2.247/29 (mask 255.255.255.248) and gave the ATT gateway the IP: 192.168.2.254 and my router's WAN port: 192.168.2.253. This was the key to making it work, as when the WAN port was masked with /24 it failed to route the packets into the router.

Glad you got it working.  None of this subnet trickery should have been necessary; not sure why you had to do this; as long at the Gateway's LAN address and your Router's "WAN" address are on the same subnet (/24, /29 or anywhere in between), they should function.

 

 

*The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.
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