Kitz Forum

Broadband Related => ISPs => Topic started by: N0STIE on January 21, 2020, 08:59:30 AM

Title: Yet another Zen thread
Post by: N0STIE on January 21, 2020, 08:59:30 AM
Hi guys,

I apologise for opening new Zen thread but couldn't seem to find anything about their latency in Northwest area.

Anyone here with Zen and living in northwest area who can ping some IPs for me? Do Zen use BT network?

Thanks guys
Title: Re: Yet another Zen thread
Post by: Alex Atkin UK on January 21, 2020, 02:28:21 PM
Zen use Openreach, their own backhaul or Talk Talk Business I believe, depending on what is available in your exchange.

They shouldn't be largely different to any other ISP though as they all tend to peer in London.

The difference is Zen are aiming to peer more locally so "potentially" could have better latency than most ISPs going forward.
Title: Re: Yet another Zen thread
Post by: mofa2020 on January 21, 2020, 08:44:51 PM
The difference is Zen are aiming to peer more locally so "potentially" could have better latency than most ISPs going forward.

May I ask what is meant by peer more locally? trying to compare things to ISPs in my country, as I live in the northern of it and I believe all the internet routed to the capital.
Title: Re: Yet another Zen thread
Post by: Alex Atkin UK on January 21, 2020, 09:47:39 PM
When you connect to the local cabinet you use the telcos fibre and a virtual lan to tunnel back to the exchange, where it uses one of the above methods to link back to the ISP which typically goes via London, no matter where you are in the country.

I believe the idea is to have their own leased fibre at the exchanges so they can link back to their their core network more directly.

What I'm curious about is if they can also peer to local data centers to the exchange, therefore not route back to their core network at all if your destination is local.
Title: Re: Yet another Zen thread
Post by: mofa2020 on January 21, 2020, 10:07:33 PM
Unfortunately this is not the case in my situation, all routed back to the core even the local content for all ISPs and I believe there is not much data centers or even at all outside the capital  :(
Title: Re: Yet another Zen thread
Post by: Alex Atkin UK on January 21, 2020, 11:43:37 PM
Unfortunately this is not the case in my situation, all routed back to the core even the local content for all ISPs and I believe there is not much data centers or even at all outside the capital  :(

There definitely are, several in Sheffield for example.  As I recall correctly, Origin Broadband used to use ASK4 as their transit.
Title: Re: Yet another Zen thread
Post by: niemand on January 22, 2020, 01:54:02 AM
Note to self to come back to this one as there are a few things that need explanation, the difference between data centres and transit and peering being one.
Title: Re: Yet another Zen thread
Post by: j0hn on January 22, 2020, 12:16:41 PM
Zen can route to Manchester or London but there system is pretty poor at directing the right users locally.

Most other consumer ISP's route straight to London for all customers.
Title: Re: Yet another Zen thread
Post by: Alex Atkin UK on January 22, 2020, 12:59:10 PM
Note to self to come back to this one as there are a few things that need explanation, the difference between data centres and transit and peering being one.

Yeah I know I messed up the definitions there as peering is to reach a target network, not for transit to other networks. ;)  Honestly, its hard to keep the different terms straight in your head when you aren't living, breathing networking.

But the crux of the matter is, Zen aim to have direct links to each exchange rather than routing everything via London and Manchester, as they are aware the current system doesn't work very well and wastes bandwidth.

What I'm not sure about is if they plan to have transit carriers more local to exchanges, effectively spreading their core network across the country, rather than having to take all traffic to one location and transit from there.  The fact they implied that Youtube, Netflix, caches would relieve bandwidth on the links back to Zen suggests some sort of peering to local data centres where these caches would reside, which would seem to blur the definition between transit and peering.  Or, perhaps more likely, I completely misunderstood what they meant. :P

Ideally you'd want a system where any two Zen customers on the same exchange, never need to hit the Zen core network at all.  This is how Digital Region seemed to work, although its hard to be sure as all transit was in Sheffield so its not like the latency would be high either way.

Either way, they seem to be much more open about the fact their current configuration is less than ideal and the direction they are planning to go to fix it.
Title: Re: Yet another Zen thread
Post by: j0hn on January 22, 2020, 01:18:11 PM
What you suggest would be unbelievably complicated.

Quote
But the crux of the matter is, Zen aim to have direct links to each exchange rather than routing everything via London and Manchester, as they are aware the current system doesn't work very well and wastes bandwidth.

Not how it works. They aim to, and do, route everything via Manchester or London.

Quote
Ideally you'd want a system where any two Zen customers on the same exchange, never need to hit the Zen core network at all.  This is how Digital Region seemed to work, although its hard to be sure as all transit was in Sheffield so its not like the latency would be high either way.

Zen would need a silly amount of kit in every exchange.
Where do all the PPP sessions terminate?
What about exchanges where Zen has no presence and uses a competitors backhaul?

CDN caches are a different thing altogether.
Title: Re: Yet another Zen thread
Post by: Alex Atkin UK on January 22, 2020, 01:33:07 PM
Rather than answering these questions that I'm not remotely qualified for, I will point to where I'm trying to extrapolate the information from and see your interpretation: https://youtu.be/MGTkxrIQXKQ?t=505

Pay particular note to the 15 minute mark where he mentions geo-locating caches, potentially as close as the exchange itself.

I'm as confused as you are, it was my understand PPP sessions all terminate at the core network, but clearly they think there is a way to do this.
Title: Re: Yet another Zen thread
Post by: niemand on January 22, 2020, 05:56:52 PM
The fact they implied that Youtube, Netflix, caches would relieve bandwidth on the links back to Zen suggests some sort of peering to local data centres where these caches would reside, which would seem to blur the definition between transit and peering.  Or, perhaps more likely, I completely misunderstood what they meant. :P

Those caches would be on the Zen network. No transit or peering involved. Youtube / Netflix / others provide ready-made racks of servers which they own, the ISP provides the switch ports and job done - content serving the ISP's subscribers cached locally so no need to use transit, peering or, indeed the ISP's own core network to get to those exit points.

Much of the content I get via Netflix and Youtube comes from basically down the road at VM's Leeds Seacroft PoP.
Title: Re: Yet another Zen thread
Post by: Alex Atkin UK on January 22, 2020, 06:33:19 PM
Yes but WHERE on the Zen network, when they are literally talking about in or close to a regional exchange?

As I described before, it sounds to me like they plan to invest in more of their network being in the exchanges themselves, or at least using nearby data centres so they  do not have to send all traffic to the core network before hitting the caches.  Sounds very complex and expensive, but it makes total sense from an efficiency point of view.

Could it be they will ditch PPP entirely and use some other method that is easier to terminate at the exchange?  Digital Region as I recall just used DHCP.

After all, its supposed to be the world wide web.  Diverse inter-connecting was the very intent, and having everyone rely on links down to London never made much sense from a reliability or efficiency context, it was just cheaper and simpler to maintain.
Title: Re: Yet another Zen thread
Post by: niemand on January 22, 2020, 06:41:45 PM
Makes no sense on any level shoving loads of kit into exchanges. It's expensive to rent power, space and cooling from Openreach and carries restrictions colocating do not.

Networks are segmented into aggregation, core and backbone for good reasons, one being it's far cheaper per bit to shift traffic around on 400 Gbit links to 9.6 Tbit routers than to have loads of routers all over the place handling 40 Gbit.

Networks are moving away from having loads of real estate. Moving intelligence into street cabinets to retire buildings and then having longer fibre runs back to aggregating those cabinets.

Regarding PPP there's nothing stopping them terminating it at the exchange. BT Wholesale do.
Title: Re: Yet another Zen thread
Post by: Alex Atkin UK on January 22, 2020, 06:54:52 PM
So what do you make of what he said in that YouTube video?  I'm clearly missing the logistics of it, unless you mean they WILL use local data centres due to exchange space being too expensive and potentially not even being available at all (lack of space in smaller exchanges + Openreach ultimately closing them)..
Title: Re: Yet another Zen thread
Post by: niemand on January 23, 2020, 11:46:54 AM
So what do you make of what he said in that YouTube video?  I'm clearly missing the logistics of it, unless you mean they WILL use local data centres due to exchange space being too expensive and potentially not even being available at all (lack of space in smaller exchanges + Openreach ultimately closing them)..

Take the Cablelink feed, put it into a switch, rent some metro capacity from Virgin Media or A N Other and get the customers to a local colocation facility.

Alternatively Cablelink into a switch, that switch to another in an exchange where there's a handover, rinse and repeat until you get near a DC then rent metro capacity to the DC.

This is how Sky's network is built - daisy-chained switches in exchanges until within economical range of one of their PoPs.

No need to put anything in exchanges other than switches with 10 gigabit ports.
Title: Re: Yet another Zen thread
Post by: Chrysalis on January 23, 2020, 01:26:01 PM
Alex they won't be in the exchange it would be where the isp has a POP.

Even if an isp has local POP's they may decide to only put caching servers in their London DC's.  e.g. I dont think sky use local POP's I think they just have a bunch of netflix caching servers hosted in london.

Some isp's if not large enough may not have any caching servers at all and it comes direct from the netflix CDN.

VM are a very big isp with their own national network so for them to put them in regional hub's is practical.
Title: Re: Yet another Zen thread
Post by: niemand on January 23, 2020, 02:04:57 PM
Just to mention Sky are a large ISP with a national network and a number of PoPs acquired from Easynet. They have CDNs on-net all over the place.
Title: Re: Yet another Zen thread
Post by: Alex Atkin UK on January 23, 2020, 03:08:25 PM
Take the Cablelink feed, put it into a switch, rent some metro capacity from Virgin Media or A N Other and get the customers to a local colocation facility.

Alternatively Cablelink into a switch, that switch to another in an exchange where there's a handover, rinse and repeat until you get near a DC then rent metro capacity to the DC.

This is how Sky's network is built - daisy-chained switches in exchanges until within economical range of one of their PoPs.

No need to put anything in exchanges other than switches with 10 gigabit ports.

Isn't that pretty much how I interpreted it?  It was Zen themselves saying possibly even in the exchange, which I assumed to mean only in extreme circumstances where they can't reach a DC and the exchange has capacity for it, which would be pretty rare.

They also specifically mentioned rolling their own metro nets in the presentation and having PoP in as many exchanges as possible, potentially all of them (seems more likely to happen due to Openreach closing/merging exchanges, can't see how/why they would do it in rural exchanges).