This topic

Hybrid Connect, network switch, separate DHCP server

lesthawk — Sun, 23 May 2021 12:37:20 GMT

FIRSTLY I AM NOT A BT ENGINEER, BUT I have spent a lot of time today experimenting to how the Hybrid Setup works in Fail over.

I have a bespoke setup... VERY bespoke. Network ports all around the house, plugged into a network switch. A Separate DHCP server, hub obviously has this feature disabled. So collectively the Hub is only responsible as a gateway to the internet, not DNS and not DHCP. I then added on the Hybrid connect.

I recently had an outage and the Hybrid connect failed to... well, fail over. In fact as part of this it took out all connectivity on my network. The hub didn't even respond to pings over Wi-Fi despite being connected and networked ports were all down too. Unfortunately the kit is so new that no-one at BT was able to advise on what the correct configuration should be when NOT USING THE BT HUB AS A DHCP SERVER. Should I plug the device into the switch or the hub, how does it actually fail over? does it reroute traffic to the Hybrid device or does it swap IPs. If you have a bespoke or business setup similar to mine you'll be asking the same questions because this will largely determine your network topology/configuration and setup

Anyway, I determined the issue was the hub and BT are sending a new one. However the current one is mostly functional and barring another weird behaviour from it it's up until the new one arrives.

I figured time to research and try to find out the correct configuration. The good news is that after trying several configurations I know both the configuration and what happens when something bad happens. The bad news is that if your HUB blows you're basically up a creek without a paddle.

First the configuration. I have the Hub as above, but I have the Hybrid Connect hooked into it by Cat6 cable. This gives the best rate of transmission at the full network capability (in my case 1gb network speeds) You can disconnect the device from the cable seems but this limited the connection to Wi-Fi speeds (much slower) and are affected by all the usual Wi-Fi related issues such as device contention and ethernet taking priority.

Next I decided to try a DR Event (Disaster Recovery) and turned off the fibre modem. This is to simulate the dropped or broken fibre connection into the home.

It took a good few minutes for the Hybrid to realise what had happened before it kicked in. From the Hub control panel you can see it's status, monitoring after it realised the connection was down it took less than a minute for it to connect to 4G. At this point it became clear it had the same IP as before on the network and the Hub had agreed to failover again on the same IP. This confirmed several things.

1. when the connection drops it seems the Hybrid is polling to see if it has connection before letting the hub know to fail over to it. If it was the hub controlling this then it would have spotted it sooner and started the Hybrid connection up.

2. The Hub redirects it's traffic to the Hybrid device. Effectively uses it as the modem and, IMPORTANTLY, this device just therefore has to be easily communicable from the Hub.

3.When the connection is back up the whole thing happens again in reverse.

Several points of note here.

1. The hybrid could be connected by switch, but doesn't need to be. Anyone who's had the issues I've seen due to multiple devices connected to the hub and others connected to a switch also connected to hub may find they can't always talk to each other. This is negated if you ONLY have the hybrid and the switch plugged into the Hub.

2. The Hybrid is slower but providing it's got at least two of the three bars showing Blue, you should be fine.

3. If your Hub blows, there's no way for the Hybrid to take over, it's not swapping IPS with the Hub and if it's blown then the Hybrid isn't being connected to as a replacement for the Hub. So beware. This is still a risk.

4. from 3. The hybrid will take over when there is loss of service or loss of the modem connected to the hub, it works in tandem with the hub.

I hope this helps some other people with their Hybrid Device setup in a Hybrid network environment. Hopefully in time BT's engineers will be shown how this thing works at a lower level than just 'turn it off and on again, is it plugged into the back'? I should stress this isn't a dig at BT, the kit really is impressive, but BT really should explain to their 3rd line support engineers, how this kit works.

Re: Hybrid Connect, network switch, separate DHCP server

lesthawk — Sun, 23 May 2021 12:39:10 GMT

before anyone points out 4G isn't 1Gigabit network speed. Yes, but my network access to the device is so the cap expectation here is that in DR mode you'll be capped at 4G speeds for internet access.

Re: Hybrid Connect, network switch, separate DHCP server

Leasty — Wed, 09 Feb 2022 18:02:02 GMT

I realise this is an old topic, but am interested in your set-up if it's still the same, as I've just ordered Halo3+ with the hybrid connect.

Is your service FTTC or FTTP and what device do you connect as the modem (if FTTC) or to the ONT (if FTTP).

I understand that the hybrid connect only works with the SH2, but not sure from your post where that sits in relation to your other equipment, particularly the network switch you use.

Re: Hybrid Connect, network switch, separate DHCP server

lesthawk — Wed, 09 Feb 2022 18:32:00 GMT

FTTP, standard modem and bt router setup.

Re: Hybrid Connect, network switch, separate DHCP server

jaymorgan25 — Thu, 15 Dec 2022 20:09:06 GMT

Hi.

I think I’m reading this right, but are you saying I can connect my hybrid connect to my smart hub via Ethernet, but through a switch?

BT are sending me a hybrid after a branch went through our fibre recently. I would like to have the hybrid up in the attic where I can rig up an external antenna as our 4G isn’t the best. This would mean the hybrid and the hub will have a switch in-between them.

Thank you.

Re: Hybrid Connect, network switch, separate DHCP server

Leasty — Fri, 16 Dec 2022 21:47:24 GMT

If it's a proper BT/EE hybrid connect 4G modem then yes, you can connect it through a switch to the BT SmartHub2. I do this quite successfully - the SmartHub2 is downstairs and the hybrid connect is upstairs near a window and there is a switch (Netgear GS116) in between. I would recommend connecting it directly to the hub to initially set it up though. Once active you can use it to access the internet from any of your devices if your main broadband link is down without any configuration changes on your devices. Changeover is automatic but there is a delay while it works out the main link is down.

If it's one of the BT mini-hubs then it's wireless only and just offers wireless access to some devices. I also had one of these and while they work you are restricted to just wireless devices and you have to explicitly connect to the WIFI offered by the mini-hub - i.e. a different network id (SSID). BT also need to activate it when your main connection has a fault.

Re: Hybrid Connect, network switch, separate DHCP server

jaymorgan25 — Sat, 17 Dec 2022 09:00:08 GMT

Thank you.

Mine is supposed to arrive today, so I will experiment soon.

Thanks.

Re: Hybrid Connect, network switch, separate DHCP server

rds999 — Mon, 27 Mar 2023 16:14:03 GMT

@Leasty I know this is old(ish), but I have a similar setup to you and cannot get the HybridConnect to work via a switch (Netgear GS108PEv3). I wondered if you (or anyone else for that matter) had any ideas about how to solve or whether it is just a lost cause because the HC relies on messaging that cannot be routed.

When I have the switch in place, everything appears to work normally but it fails to provide the backup service:

The Hub recognises the HC and vice versa: both show full blue status with the WAN (full fibre) connected
When the WAN is disconnected from the Hub, the HC waits a while and then connects to the EE Network
At this point the Hub is flashing purple and the HC is full blue with white bars indicating working normally and connected to EE

However, the hub never detects that the connection has been made and remains flashing purple.

The Mobile IP address stays at 0.0.0.0 and I think this means the Hub cannot route the internet traffic to the HC.
The HC eventually fails, the bars go flashing red and it needs to be restarted to recover.

BT support, very helpful, told me during diagnosis that the HC will only work directly connected to the Hub: wired directly or wirelessly . This is correct in my case. Direct connection to a port on the back of the hub and wireless both work (same delays, but they get there). As soon as I put the switch back in the path, it fails to work.

Any ideas?

Re: Hybrid Connect, network switch, separate DHCP server

Les-Gibson — Mon, 27 Mar 2023 17:59:56 GMT

Just a suggestion and I'll own up now, I know absolutely nothing about Hybrid Connect or how it works.

Could it be that the Hybrid Connect is also running a DHCP server and causing complications?

Re: Hybrid Connect, network switch, separate DHCP server

rds999 — Mon, 27 Mar 2023 18:55:31 GMT

Thanks @Les-Gibson . I'll look into it. Can't think that it has, otherwise I would expect mega problems with dupliated ip addresses, and I have none of those. When I get a moment, I'm going to wireshark the fail over in both scenarios to see what's happening.

Re: Hybrid Connect, network switch, separate DHCP server

Les-Gibson — Tue, 28 Mar 2023 10:32:34 GMT

@rds999

It might be worth checking if the Hybrid Connect does have it's own DHCP server and if so in what subnet it operates

Re: Hybrid Connect, network switch, separate DHCP server

Keith_Beddoe — Tue, 28 Mar 2023 10:48:56 GMT

Hybrid connect is just a modem which needs to connect to the BT Smart Hub 2 which provides the router function.

Re: Hybrid Connect, network switch, separate DHCP server

rds999 — Tue, 28 Mar 2023 11:19:22 GMT

@Keith_Beddoe Thanks. Saved me from a rabbit hole! If the HC is just a modem, then it needs the router before the switch to do DHCP/NAT so the rest of the network can share the modem's public IP address.

Re: Hybrid Connect, network switch, separate DHCP server

Keith_Beddoe — Tue, 28 Mar 2023 11:30:03 GMT

Its purpose is to provide an alternative WAN connection should the primary WAN (fibre, or copper VDSL) become unavailable.

Re: Hybrid Connect, network switch, separate DHCP server

Leasty — Tue, 28 Mar 2023 14:48:59 GMT

I haven't had need to use the hybrid connect device as my main feed has been fine (famous last words) but will try it again when convenient - other members of the family working from home at the moment.

There has been a SmartHub 2 firmware upgrade since I last used the 4G so maybe that has introduced an issue? Firmware on my hub is v0.38.00.10147 and on the hybrid device is v0.22.03.202210140100-BT

My last "Resilience event" was 12/10/22 and I had the GS116 in place then, but lower level of firmware on the hub.

Your GS108PE has some management functions whereas the GS116 I use is a "dumb" switch, maybe that is a factor. I suggest you try with a non-managed switch as a start.

Will post the results of my test when I can.

Re: Hybrid Connect, network switch, separate DHCP server

bensteventon — Tue, 28 Mar 2023 17:41:12 GMT

I have my hybrid connect linked to the hub by Ethernet via two unmanaged switches - one Netgear and one TP Link. No issues and fails over correctly when tested, to the full 30/5mbps

Re: Hybrid Connect, network switch, separate DHCP server

Leasty — Wed, 29 Mar 2023 14:54:25 GMT

@rds999

Well, I've now tried hybrid connect failover in my setup - Netgear GS116 switch between hub and hybrid modem - and failover worked fine. Took about 4 minutes to switch over - about a minute before it started to failover (blue to flashing purple on the hub) after unplugging the cable to the NTE and another 2m30s for the failover to complete. Things worked fine on the hybrid modem albeit slower due to not having a great signal.

I did have a problem failing back and after waiting about 10 minutes had to power off/on the hub but it then all came back fine. Suspect it is as much to do with the hub not having been powered off in months and a firmware update happening during that time. Have got all the event log if you need anything from that.

I suspect your managed switch is the issue and would suggest trying with just a standard "dumb" switch.

Good luck

Re: Hybrid Connect, network switch, separate DHCP server

rds999 — Wed, 29 Mar 2023 16:09:19 GMT

Thanks. I could try an unmanaged switch... it seems to be the way forwards. My managed switch is set up to do nothing on the relevant port, except IGMP snooping, so should not be a problem, but clearly is: I'm wondering if a VLAN is set up between the hub and HC when in fail over mode. I think my switch would reject those packets (though I'm at the limit of my knowledge). I'm going to leave the HC running over WiFi instead of a fixed connection as I shouldn't need it (again!) and *could* run a long cable through to it instead if I did!

Thanks to everyone for their suggestions and help.

Re: Hybrid Connect, network switch, separate DHCP server

licquorice — Wed, 29 Mar 2023 16:14:29 GMT

I'm intrigued to know the purpose of putting a switch between the HC and Hub.

Re: Hybrid Connect, network switch, separate DHCP server

Leasty — Wed, 29 Mar 2023 20:11:01 GMT

@licquorice I use a switch between the Hub and hybrid modem because of the distance between them and not wanting to lay extra cables.

My BT line comes in at the front of the house and is where the Smarthub is - provides wifi at the front of the house. The hybrid modem is upstairs at the back of the house in my study - just about as far away as it can be - to get the best 4G signal. That means there is only a poor wifi signal between the two. I already have my main PC, NAS, AP and main switch in the study so it was a no brainer to put the hybrid modem on the switch as long as it worked. Means I have a cabled 1Gbps link between the Smarthub and modem.

If the 4G signal at the front of the house was good, I'd have the hybrid modem there, but no such luck.