BT NET Fibre Failover

We have a current BT Net fibre dedicated line. A few months ago, a worker "put a shovel through the cable" and we lost the service for a few days.

The boss ordered the Failover product from BT to avoid this scenario in future. The selling point being that the equipment would sense the interruption and seemlessly switch to a different feed, through a fibre cable that takes a different route.

We've been told that they're coming tomorrow to get the fibre into the building and that we can expect a second Cisco 4321 router. We currently have an ADVA FSP 150 to terminate the current fibre cable which feeds to a Cisco 4321. We plug our firewall into the Cisco.

Does anyone know if this second Cisco router is neccessary for the Failover service or has someone at BT made a mistake?

I would've thought that the intelligence and capability to switch between the two feeds would all happen inside the ADVA.

Apart from anything else, we don't have room in the network cabinet for a second Cisco 4321.

Thanks.
Luca

BT NET SLA's are pretty tight from memory so unless you're some big old data centre, sounds a bit overkill to use a redundancy fibre line. I thought BT Business did 4G backup now for most of their customers?

From my experience dual routers are installed on premise that do some clever stuff to enable the public IP to be delivered via either circuit

This document may help explain the options

https://business.bt.com/assets/pdf/broadband-and-int...

John

Edited by john_32 (Thu 11-May-23 11:17:08)

In reply to a post by lucavigg:

Does anyone know if this second Cisco router is neccessary for the Failover service

Yes, it is for full redundancy - you should expect to get a second ADVA as well. Then if either of the ADVAs or Ciscos fail, your connectivity will continue.

You'll have to pay for the power to all 4 devices, of course.

This approach makes sense for a data centre. For an office, you might be better off with 5G backup - or some service which is unlikely to share much infrastructure with your BT leased line, such as a Virgin Media circuit.

Yeah they will be using HSRP or something similar.
The local routers WAN Port will need to to go to a switch then both cisco routers will connect to this,
The local router will then use an IP that is shared by both devices as its default gateway.
The primary router/connection will have this IP, if this falls over it will transfer to the backup router/connection.

Thanks
Dan

In reply to a post by lucavigg:

….sense the interruption and seemlessly switch to a different feed, through a fibre cable that takes a different route.

There will still be single points of failure, especially if someone puts a digger bucket somewhere they shouldn’t.

If you’re going to all this trouble and expense - you really want diverse fibre from different PoPs / exchanges and taking a completely diverse route, including a different entry point to the premises / property.

Otherwise an exchange level fault could see you out of action or a digger on your doorstep could in theory take out both ‘diverse’ fibres if they’re using the same footway chamber / entry conduit for example.

Similarly if your own equipment has single points of failure then you could be spending money needlessly. It’s all about ID’ing the most likely points of failure and their consequences.

@candlerb’s comment above about a different method of connection - 5G or similar has a lot of merit.

Thanks for that. I'll take a look.

If what BT are providing is an RO2 service then there will be full fibre path diversity and the circuits will terminate in different exchanges. I agree that there are usually better ways to spend money than trying to add uptime by purchasing more fibres though.

Edited by jpm (Thu 11-May-23 14:48:13)

Oh, this is very bad news. We definitely haven't got room for a second ADVA and we're tight on places to put a second cabinet.

Unfortunately, the boss was persuaded and signed on the dotted line before I got involved. Seems somewhat overkill, as others have said.

I can sort of understand his concern. He runs a high turnover food distribution business. Attended operations are from midnight until 4PM the next day. The bulk of the orders from buying consortia, large hotels and restaurant chains come in between 4PM and midnight, when no one is on the premises.

I think he latched onto the idea that it would be a seemless failover if something were to go wrong. It's just a shame he didn't mull over his options some more before committing.

Edited by lucavigg (Thu 11-May-23 14:56:33)

The ADVA NTEs can be wall mounted if you are tight on space