This is the first time I am encountering this, and it has me a bit confused as to how to set this up. I think I might need a new router to accomplish this. I have a Cisco RV325

The local ISP has me setup with a Fiber line just installed. I am only familiar with configuring a small business router with a static IP block.

The configurations I have from my ISP for my static IP's is similar to the below.

Customer Layer 3 IP Information (WAN BLOCK) Link IP Address: Gateway: Layer 3 IP: Layer 3 Subnet Mask:

Customer Usable IP Information (LAN BLOCK) Usable IP Block: Usable IP Ranges: Usable Subnet Mask:

If this were a typical ISP transparent bridge setup, I would have no problem setting up this internet connection.

I am confused as to how I would configure a link from router WAN port to switch and then set up my public IP block. I am starting to think it is not possible with the RV325.

I would need natting on one of the static IPs. Any suggestion on where to head in the right direction? Do I need to order a better router with more enterprise features?

Any push in the right direction would be incredibly helpful.

The only thing I can think of is setting up my WAN as a static IP, and then a VLAN with my subnets but then I can't figure out how to have my static IP block routed to my local network. I am just confused, and I haven't looked at routing information like this in ages.

  • Ok it looks after even more research this is a common isp configuration. a /30 trasnport and /29 usable ip space. I am thinking of going with a cisco asa5506? any thoughts? Jul 15, 2016 at 22:51
  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can post and accept your own answer.
    – Ron Maupin
    Jan 5, 2021 at 18:31

2 Answers 2


This is indeed a typical config, and most likely doesn't require you to change your hardware.

On one hand, you have the /30 which will be used on the point to point WAN link between you device and the first IP device on the ISP's side. So you should set your device up with the IP they gave you (.142) and a default route pointing to the ISP's device at .141

Then, they are saying they have assigned a /29 block go you. What this means is basically that there is a static route on their side pointing to you WAN IP (.142) for that /29 range such that any traffic for that range is sent to your router. At that point it's up to you to decide how to use it.

You can either route it to another device on your network (a firewall, say) with a static route, or use it on the router itself for handling NAT rules. The range does not need to be associated with any physical interface on the device: the router will be receiving the traffic anyway, due to the ISP's static route, it just needs to know what to do with a packet reaching it with a dest IP in that range: route it further, or process it.

  • Upon research, I saw what you mentioned. MY concerned was that my Cisco RV325 cannot do this. IT is more of a small office device apparently. I did end up purchasing the firewall ASA5506 for our office. I figured this way we can keep using our same router and get the added benefit of a firewall. We do have a few VOIP servers that can benefit from the firewall. Jul 16, 2016 at 16:09
  • 1
    For the sake of argument, I suspect your RV325 would have handled it just fine despite the SOHOish way it presents its features. It supports One-to-One NAT, and firewalling which is all we are really talking about here. Performance on paper isn't all that different either ! Jul 17, 2016 at 4:43
  • I am accepting this comment upon review as it explains the solution better. The RV325 could not handle the scenario, but indeed using another device in between, say a firewall, solved the problem initially. Thank you. Aug 15, 2017 at 15:13

So it turned out the RV325 has features like this oyrpousfully unavailable. It is primsrily set as a SOHO solution and my use was moving away for what it supported.

My fix was to move toward a PFSense router on an old dell blade server I got for 70 bucks. I manage a call centrr with about 80 agents with no hiccuos now.

So in short, the RV325 cannot handle this sort of routing by default.

  • You should accept your answer so that the question doesn't keep popping up forever, looking for an answer.
    – Ron Maupin
    Aug 15, 2017 at 1:59
  • You know I wrote it on mobile, and I couldn't find the accept answer button. Thanks for the heads up. Aug 15, 2017 at 15:11

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