"LAN" in this context means the customer facing side of the managed router. If you're providing your own router then you configure a /31 to talk to the ISP and then you have your routed subnet to do what you want with.

Some ISPs configure the WAN side of the managed router with private IP space to conserve their allocation.

Yes. That is certainly the case if you pass on the addresses with a conventional IPoE setup - if you use /32 point-to-point addressing, assuming your devices support it (e.g. Mikrotik), or PPPoE to onward clients you can actually use all four addresses

Sounds right to me.

When I had a /30 from Cerberus I used private addressing on the inside, giving the three additional public addresses to three servers as loopback addresses, with static routes to those servers. That avoided burning the "network" and "broadcast" addresses.

Hi Guys,

I have now been given my TTB WAN/LAN address and it would appear it is a /30 subnet?

Does it make much difference?

They've just given you the one /30 subnet? That's a block of 4 addresses.

For example, let's say it's 192.0.2.64/30, which is the 4 IPs 192.0.2.64, 65, 66, 67. (The lowest one will always be a multiple of 4)

Have they also given a WAN IP address, which is one of the middle two of those, for example 192.0.2.65? And a separate default gateway IP?

Then the "traditional" way to do this is as follows. On the router:

- configure the WAN as a point-to-point with IP 192.0.2.65/32 (netmask 255.255.255.255) and the default gateway as whatever they told you

Then EITHER:
- configure the LAN as 192.0.2.65/30 (netmask 255.255.255.252)
- Connect *one* device downstream of the LAN port on IP address 192.0.2.66/30 with default gateway 192.0.2.65
- That would traditionally be some separate firewall that you plug in and performs its own NAT

OR:
- configure the router LAN with private IPs
- enable NAT on the router itself
- this leaves you with 3 spare IPs for future use (can be used for port forwarding, or statically routed to a server which has it configured as a loopback address)

In reply to a post by jurassic86:

Hi Guys,

I have now been given my TTB WAN/LAN address and it would appear it is a /30 subnet?

Does it make much difference?

With all these types of questions the relevant information is "what did the order say you were getting"

In reply to a post by jpm:

In reply to a post by jurassic86:

Hi Guys,

I have now been given my TTB WAN/LAN address and it would appear it is a /30 subnet?

Does it make much difference?

With all these types of questions the relevant information is "what did the order say you were getting"

I suspect there is no order.

In reply to a post by Whitehall11:

I suspect there is no order.

Finally someone is prepared to say it.

In reply to a post by PCJM40:

In reply to a post by Whitehall11:

I suspect there is no order.

Finally someone is prepared to say it.

These Walter Mitty types come along every so often - with the 'Oh help me, i don't know how my complex leased line order, that costs £300+ a month to run works'.

If they had come to the forum with advice on how best to setup a network to solve a problem, i'd find it more believable or even a genuine technical question. If you're buying a leased line product and don't have much technical knowledge, most suppliers will offer you all the kit and support you need for and not point you down the wires only approach which these questions usually are pointed at.

Edited by Whitehall11 (Wed 22-May-24 22:12:11)

In reply to a post by Whitehall11:

These Walter Mitty types come along every so often - with the 'Oh help me, i don't know how my complex leased line order, that costs £300+ a month to run works'.

Yes, reading through all the OP comments it does sound like a massive jackanory, first a kiosk at the gate for the NTE and now its become two houses for servants, OP is going from a 4G router in loft to becoming a datacentre and then complaining about the huge cost of a router for a £300 a month leased line.