How Do You Connect To CityFibre - PPPOE etc?

Does anyone know how you connect to the CityFibre network?

Do you just use PPPOE username / password and it just works like FTTC with BT?

Thanks

It depends on your ISP. CityFibre is a wholesale network: they just pass the traffic through to the wholesale customer. How they terminate sessions is up to them.

Like with Openreach FTTP it depends on your chosen ISP, CityFibre are the wholesale supplier.

CityFibre support DHCP or PPPoE, I've seen both used on different ISPs.

You also need to know the VLAN - VLAN0 (802.1Q header used for setting the 802.1P priority bits only) and VLAN911 seem to be the most common. I think VLAN101 may have appeared as well with one ISP. The VLAN0 approach can be problematic as a lot of consumer kit does not support that.

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/at... is quite useful to explain VLAN0 stuff.

Thanks for both replies very useful.

I wish ISPs made it easier to use your own equipment.

I have no altnets available yet but doing a search CityFibre seem to be one of the biggest.

It appears Vodafone resell CityFibre there are quite a few posts on using their Support Chat to get username and password details.

This is concerning as you may sign up and not be able to use the service with your hardware if they decide not give up these details.

From my experience Vodafone are happy to provide PPPoE details.

Any provider can make it difficult I guess, but pretty sure most will provide them when asked, then just a case of correct VLAN tag and you're done.

In reply to a post by Ad_G:

CityFibre support DHCP or PPPoE, I've seen both used on different ISPs.

Interesting, which ISPs don't use PPPoE?

In reply to a post by nemeth782:

Interesting, which ISPs don't use PPPoE?

Talktalk is the best known example.

In reply to a post by candlerb:

In reply to a post by nemeth782:

Interesting, which ISPs don't use PPPoE?

Talktalk is the best known example.

Ah, don't think they offer CF in Ipswich. I'd really rather avoid PPPoE but I think I will be stuck with it.

TalkTalk was the one I am aware of that uses DHCP on CityFibre.

Looks like TalkTalk, Zen and Air are your current choices in Ipswich, so you could avoid PPPoE with TT.

What's the issue with PPPoE?

Mikrotik routers support "baby jumbo" frames (MTU 1508), and so does the ONT. Enabling this gives me a full standard 1500 MTU for IP datagrams, which means the effect of the PPPoE header is minimal.

(This works with FTTC too, with a Draytek Vigor130 modem)

It isn't the packet length that's a problem. It is the router processor requirement for handling the PPPoE protocol, which is significant with a gigabit connection. Most home user routers cannot cope with it.

In reply to a post by Realalemadrid:

Most home user routers cannot cope with it.

Older and cheap home routers cannot yes, but that is why the ISPs provide a router. More expensive routers can and those that have hardware acceleration.

In reply to a post by candlerb:

In reply to a post by nemeth782:

Interesting, which ISPs don't use PPPoE?

Talktalk is the best known example.

Are there any other ISPs beyond TalkTalk (resi), or is it just them using IPoE/DHCP either on CityFibre FTTP (or for that matter Openreach FTTP)?

There are two things:

Packet overheads, it doesn't matter if your kit supports 1508 bytes for the PPPoE header, you are still using bandwidth for the PPP headers you don't have if you are using IPoE. A lot of ISP kit will also not support an IP MTU above 1492. Your overall IP throughput is lower if you use PPP.

Processing overheads, PPPoE adds a lot of processing requirements to the equipment so for the higher speeds on FTTP you need higher end/more expensive kit For PPPoE vs IPoE. Yes there is kit out there that can hand it but it tends to cost more and use more power.

In terms of ISPs, I am aware of TalkTalk on CityFibre and Sky on Openreach using IPoE/DHCP rather than PPPoE

In reply to a post by Ad_G:

Packet overheads, it doesn't matter if your kit supports 1508 bytes for the PPPoE header, you are still using bandwidth for the PPP headers you don't have if you are using IPoE.

You're talking about a difference of under 0.5% for normal traffic (i.e. TCP with mostly large frames).

In reply to a post by Ad_G:

Processing overheads, PPPoE adds a lot of processing requirements to the equipment so for the higher speeds on FTTP

I disagree with "a lot". Adding 8 bytes of fixed header, and removing them again, is not a big deal for the processor, compared with all the other stuff it has to do. So I think you're worrying unnecessarily.

Note that when you access a site using IPv6 rather than IPv4, it'll be using an extra 20 bytes in the IP header - a much larger difference, but still insignificant in the bigger picture of the user-perceived performance.

But then again, without referencing speed test tools, I don't think most people would notice the difference between a 300M service and a gigabit service. More often than not, the bottleneck is the client device anyway.

Do you know if Sky still uses the DHCP option 61 string for authentication with their Ultrafast FTTP services?

In reply to a post by Ad_G:

TalkTalk was the one I am aware of that uses DHCP on CityFibre.

Looks like TalkTalk, Zen and Air are your current choices in Ipswich, so you could avoid PPPoE with TT.

Interesting, well, if/when CF ever reach my house (they are doing roadworks everywhere but where I am it seems!!) I will probably go with TT then,

In reply to a post by jchamier:

In reply to a post by Realalemadrid:

Most home user routers cannot cope with it.

Older and cheap home routers cannot yes, but that is why the ISPs provide a router. More expensive routers can and those that have hardware acceleration.

My router is a UDM-Pro, it can do 8gbit WAN->LAN over SFP+, or 3.5gbit with IPS/IDS on.

However, PPPoE chokes it, the implementation is poor and it runs single threaded, most people can't get over ~600mbit or so.

Yes, I could change the router, but honestly I'd rather avoid PPPoE, it's awful anyway.

In reply to a post by candlerb:

You're talking about a difference of under 0.5% for normal traffic (i.e. TCP with mostly large frames).

For FTTP it is not so high, was more of an issue on xDSL where typically it was PPPoEoA which gave much higher overheads, but with VoIP and other applications that use smaller packets it is still an extra overhead you don't really need.

In reply to a post by candlerb:

I disagree with "a lot". Adding 8 bytes of fixed header, and removing them again, is not a big deal for the processor, compared with all the other stuff it has to do. So I think you're worrying unnecessarily.

The problem is that most PPP implementations make much harder work of things than just adding a PPPoE header, they maintain the state of the PPP session and have very heavyweight implementations that probably date back the early implementations on dial-up! Think building a full virtual interface, maintaining state and having lots of interface features you probably never need. On a lot of boxes PPP can drop the throughput by over 50%.

Equally you have to remember that PPP has been used in broadband networks since the dawn of time (in the form of PPPoA and PPPoEoA), and in dial-up before that. The BRASes at ISPs are heavily optimised for it, and the routers that most ISPs supply expect to use it.

If you have a router that suffers "50% throughput loss" due to PPPoE, then it's junk. I've only heard one example of such a thing, and that's the UDMP.

In reply to a post by candlerb:

Equally you have to remember that PPP has been used in broadband networks since the dawn of time (in the form of PPPoA and PPPoEoA), and in dial-up before that. The BRASes at ISPs are heavily optimised for it, and the routers that most ISPs supply expect to use it.

The "high speed serial" links we used at work for years (2mbps and faster) were all PPP links within enterprise Cisco or Juniper routers.

Domestic grade routers from Asus have hardware support for PPP with 0% CPU impact, so it seems that UDM is junk, not fit for purpose.

In reply to a post by candlerb:

Equally you have to remember that PPP has been used in broadband networks since the dawn of time (in the form of PPPoA and PPPoEoA), and in dial-up before that. The BRASes at ISPs are heavily optimised for it, and the routers that most ISPs supply expect to use it.

If you have a router that suffers "50% throughput loss" due to PPPoE, then it's junk. I've only heard one example of such a thing, and that's the UDMP.

UDMP is what I'm running, and 8Gbit without IPS, 3.5Gbit with IPS, and 600mbit with PPPoE is more than 50%.

pfSense can't even do gigabit PPPoE on anything less than a full fat i3, an atom etc will struggle.

Many "high end" consumer routers cannot do gigabit PPPoE. Many of the Mikrotik devices struggle (or, can do it but have no CPU left for anything else)

It's needless, there is no benefit to PPPoE, it's common in the UK but far less so in other countries, and honestly needs to die.

Edited by nemeth782 (Thu 23-Sep-21 18:41:04)

In reply to a post by nemeth782:

far less so in other countries, and honestly needs to die.

Do those other countries have shared infrastructure? ISP neutral "last mile" networks such as Openreach and Cityfibre ? Virgin Media doesn't need PPPoE as the only ISP on the physical network.

My USA friends can't change ISP without moving house / town. It is that fundamental.

In reply to a post by candlerb:

What's the issue with PPPoE?

Mikrotik routers support "baby jumbo" frames (MTU 1508), and so does the ONT. Enabling this gives me a full standard 1500 MTU for IP datagrams, which means the effect of the PPPoE header is minimal.

(This works with FTTC too, with a Draytek Vigor130 modem)

PPPoE is cpu intensive, opensource implementation especially has issues with it, single threaded etc.
Then there is the MTU problems, its out right inferior, but there must be something good about it as most UK providers use it.

The head of BTw in a presentation years back said he hated and it would be gone on ultrafast, but its still here so I guess he got overruled.

Edited by Chrysalis (Fri 24-Sep-21 02:36:19)

In reply to a post by jchamier:

In reply to a post by nemeth782:

far less so in other countries, and honestly needs to die.

Do those other countries have shared infrastructure? ISP neutral "last mile" networks such as Openreach and Cityfibre ? Virgin Media doesn't need PPPoE as the only ISP on the physical network.

My USA friends can't change ISP without moving house / town. It is that fundamental.

Right, but there are other solutions to that, eg IPoE, DHCP as talktalk manage to achieve on Cityfibre.

Sky use DHCP on Openreach FTTP and FTTC and at one point on ADSL in some areas probably for testing.

So I gathered from @Ad_G reply above. Are they continuing to use option 61 for FTTP?

They are still using option 61.

Thanks for confirming.

So essentially only TalkTalk (resi only as TTB use PPPoE) and Sky use IPoE/DHCP on the large wholesale networks of Openreach and CityFibre.

All other ISPs on these FTTP nets are then using PPPoE….unless anyone knows of others?

Edited by Pheasant (Fri 24-Sep-21 09:50:29)

In reply to a post by nemeth782:

It's needless, there is no benefit to PPPoE, it's common in the UK but far less so in other countries, and honestly needs to die.

Agreed, PPP or PPPoE has not been needed since the introduction of the Openreach GEA FTTC products for most implementations here, but PPP just won't die in the UK.

Only the L2TP type products need it e.g. BT Wholesale WBMC shared, some TT Business stuff.

In terms of Open Access suppliers (e.g. Openreach, CityFibre) customer separation is done via the stacked VLANs on the service, so IPoE using DHCP is fine, the customers are in different SLVANs and CVLANs so are kept separate without PPP. If the end ISP wants to validate the user most of the providers will inject end station ID info into PPP or DHCP flows and you can use authentication options on DHCP.

Sky on Openreach and TalkTalk on CityFibre using IPoE/DHCP show there is no reason For PPP on services today.

The comment about PPP being around for a long time and hence is common in vendor implementations is true for the UK but you will find IPoE is far more common worldwide and the feature sets/performance/cost for the ISP end is often lower than for PPP now. Some of the major router vendors PPP support on BNGs has been shockingly bad over the years too.

I suspect the main reason the UK has clung onto PPP is simply that the ISP systems are so massive and complex that the move to IPoE is seen as a major barrier when compared to launching the new product using the old trusted PPP!

Air Broadband are apparently DHCP according to their support.

They also use CGNAT, but offer a public IPv4 for £3/m

Yes apologies to Air Broadband, I cruelly used them as an example and a proxy to illustrate the various download/upload symmetry, speed tiers and prices as they conveniently summarise their offerings available from the various FTTP networks where they are on-net. I’ve no experience of them otherwise 😀

Oops apologies (clearly not caffeinated yet) - cross threaded 🤣 I thought you were replying to this thread post.

Edited by Pheasant (Sat 25-Sep-21 08:20:14)