Public service announcement ...

Ah. Time to change your ISP I suspect. Is it not BT fibre then? Double NATTING should actually work...

I used to run (for a client) an MS Small Business Server behind double NAT, and often accessed its PPTP VPN (20 years ago) through my own double NAT. Online games were not played at either end, so there was never a problem. Apart from my first few years on the Net, I've always run double NAT.

I don't. But SWMBO is wheelchair bound

See above

I had to add an old 2Wire router into the mix as some IoT things insist on a pure 2.4GHz network, not a dual 2.4/5 one.

The point about relying on the internet is well taken. However whilst I am sure it would be possible to setup a local voice-control hub and may be worth working towards it, for *now* SWMBO can enjoy some semblance of normal life.

Oh wow! And there's scope for more, such as a wireless doorbell.

That's a single subnet with a /16 mask. Class A/B/C have been dead and buried for 30 years, you can pick whatever granularity you like, eg a /23, /19 or whatever. If you do that it's still a single subnet.

I meant putting two subnets say 192.168.2.0/24 and 192.168.49.0/24 on the same interface. You can assign the IPs to the interface, but suppose a client wants to do DHCP - which subnet does it get an address in? Yes you can configure the DHCP server to give fixed mappings in either subnet and default to allocating unrecognised devices IPs in one subnet.

I'm also not sure what happens with broadcast traffic, such as mDNS.

That's what I mean about it can be done, but it's messy.

Theo

Its probably ZEN. I use ZEN for Fibre but use a third party VOIP service. As ZEN don't lock down the router I can use that to connect to my VOIP provider.

Dave

Yes it is OpenReach. However the ISP is Vodafone, who don't generally release the required details.

Hiding VoIP details is quite common. TNP's ISP do it too, IDNet. I suspect this is because of the VoIP support issues related to people using their own equipment.

I'm also not sure if "won't release details" is the same as locking down the router so you can't find them for yourself.

Anyway, when I set up a new IDNet connection for my late mother, I didn't take IDNet's own VoIP offering. I went with A&A which was a little tricky to set up, different to Sipgate, but ultimately fine.

For low use A&A are perfect. I will switch to them myself when my Sipgate credit runs out (if it ever does).

That is interesting, I didn't know I could use non VLAN switches. My router only has two NIC interfaces WAN and LAN, so this info is potentially useful. I thought about VLANs 10-15 years ago, for a dual WAN setup I had at the time, but discounted a VLAN due to non-compliant switches, perhaps I was wrong. Although, maybe there were other issues, like subnet broadcast stuff. Anyway, too long ago for me to remember.

My router, pfSense, allows me to define "Firewall ALiases". Which are arbitrary groups of IPs. I can define firewall rules like "no phone home" on an Alias basis.

The problem with open source router software, is that once you get happy with one, the thought of changing becomes horrific.

FWIW, many weeks of "no phone home" killed my mesh WiFi. No phone home blocked each mesh node's ntp time sync, to a hardcoded WAN address, eventually they got out of sync and went into go slow mode.

Broadcast traffic doesn't care about subnets, so it will be visible from all of the subnets on any interface.

John

I apologise completely. The thought of an extreme disability did not cross my mind.

Unfortunately it's both.

I may get my son onto it when he is next home - he's just gained a 1st class honours degree in Cybersecurity and Forensics (plus the Dean's award for excellence in the subject); was on the committee of the university's Hacking Society; works for the authorities in that field; and loves nothing more than hacking routers - he's usually got at least one with wires coming out to access its JTAG interfaces.

Oh. Ok. I thought the idea was just to extend address space. A B C exist as conventions still.

DHCP isn't really designed to exist across two subnets. I mean if the tow subnets are not physically separated at some point, what is the point of making them separatte at all?

I can create a second LAN network here but the proviso is that it's accessed via a different wifi SSID. And that has a difference DHCP server assigned.

If you are fully wired at some level you would need to isolate the two networks for there to be any point in having them

Don't think that is any problem once you get the thing working.

Well that is crap. Time to change to an ISP who does.

When I moved from ASL to fibre i didn't even change the PPP login. IDnet kept everything the same.

In fact from there perspective I am not sure anything HAD changed, They probably saw the same frames coming in to their termination kit ...just via a different mechanism.

There are ISPs who gear their tech towards numpties, and there are ISPs who are happy to support technically sophisticated ones.

Yep. Which is why I will probably not use them for VOIP. They are selling IIRC BTs servie only

Could well be.

Agreed. Sound plan

Sadly used to it.

The older I get, the more I subscribe to the principle "do not let perfection be the enemy of progress".

Yes, what I have is a lash-up. However, having started 10 years ago in various ways, I'm pleased I did. Because I am now 10 years down the line whilst most things haven't moved at all.

Currently my biggest bugbear is that if the internet goes down, a lot of devices won't work by voice. Now if there is a power cut then it's obvious that internet or no internet, you are shafted.

However I've had 2 internet outages in the past 12 months, and they have been a nuisance. I have a 5G dongle, but not yet found a suitable failover router.

There is also the ink cartridge problem that really I need an everlasting SIM that is PAYG. And a network config that puts the smart crap into it's own little subnet so that the failover internet isn't streaming the latest Netflix in 4K ...

Yes, and the consequence is... what exactly?

I think for mDNS you'll have a broadcast saying 'hey I'm an HP Laserjet Whatever, my hostname is laserjet-whatever.local, my IP is 192.168.49.33 and I'm a printer!' and then clients on both subnets will see that. So a client on the .2.x subnet will autodetect the printer on the .49.x subnet. But I think the .2.x client won't have a direct route to that printer, so it'll send traffic via the router. If the router chooses not to forward traffic between the subnets then attempting to print will fail.[1]

Basically you have kind of a halfway position between having all the clients on the same subnet and having them on separate networks, with complications where they in one camp or the other.

Theo

The consumer 'smart' switches support VLANs, QoS and other things that you'd expect to find in a 'big' enterprise switch, but they barely cost any more than an unmanaged switch nowadays. It's got to the point where gigabit ethernet is sufficiently slow compared to modern silicon that these features come almost for free.

Once the firewall rules get too complicated it gets messy to change them :-)

I wonder if they will accept an NTP server sent via DHCP? That could be a way to retarget them to an internal server.

I suppose you could also NAT the hardcoded WAN address to something else, eg something internal? Or hijack their DNS if they are doing a lookup first?

Theo

I've been using A&A VoIP for at least ten years. Light outgoing use, and heavier incoming. We have ten numbers, for various reasons. In our case, I run Asterisk, which just registers with their servers.

A while ago I moved my Sipgate number to A&A. Painless, and they refunded my outstanding balance of about six pounds!