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  Reply # 236455 17-Jul-2009 14:34 Send private message

cyril7:
So each cabinet has 7 GigE links. That means with 196 suscribers they would get 32mb each.
Or 140 lines at 50mbp.
Does that sound right?


No, the ISAM system consists of a host shelf, that can accept upto 7GigE uplinks, this host shelf has 10 downstream GigE links, each extension shelf has a single GigE uplink from the host shelf. Each shell either host or extension can support 4cards x 48 DSL ports = 196.

So the reality is at best 1xGigE per 196 ports or if on a fully maxed out system 7GigE over 1960ports, this works out at 5Mb/s at best or 3.5Mb/s if fully fitted. Obviously Telecom could fit just one GigE to feed the whole 1960 ports, but as I understand it thats not whats provisioned. Exactly what is provisioned is the business of Telecom. So if we presume best case 3.5Mb/s full chat with a 10:1 contention ratio (which is a good business class) giving 35Mb/s (therefore exceeding ADSL2+ full line rate) then there is no reason why Telecoms new ISAM based system cannot provide first class performance.

Excatly what they provide is their business.

Nokia/Seimens and Huwaai gear used by Orcon and Voda give similar levels of access and port density.

Cheers
Cyril


Telecom's agreement with previous government was for 80% of users to be cabinetised with FTTN (or was that 80% of lines?) within 5 years and they are progressing on that quite well considering the size of the job. FTTN means fibre to the cabinet, and generally ADSL from the cabinet to the user. Theoretically they could install GPON cards onto the ISAM to connect fibre subscribers if the local fibre co wanted to build a more neutral neighbouring cabinet for other ISPs to use their own splitters. They could not bypass the cabinet for unbundled [ADSL] users who wanted to stay connected to the exchange, since interferance would make the line unstable or unusable (and slow like dialup).

I dont know what actual contention Telecom use, but I suspect around 50:1 on the bigger ISAM nodes if an imaginary 10Mbps target per user was possible. Telecom should have minimum 2 links to each cabinet for redundancy, maybe in a ring or sharing bandwidth at the exchange. For example, if cabinets were fed by 12-strand cables, they might use 2 pairs for the Telecom node and keep the remaining 3 pairs for access seekers. Also worth noting that different fibre technologies need a single strand or a pair.






Qualified in business, certified in fibre, stuck in copper, have to keep going  ^_^

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  Reply # 237718 21-Jul-2009 23:34 Send private message

Regs:
EnzoYug: But wait for how long? We'll be paying hand over fist to a bloated old dinosaur company that has been bashing us for ages. Fibre-to-the-door isn't right around the corner.

Perhaps I'm wrong but I haven't seen teams of trucks ripping up the streets laying fibre like it's going out of style. Have you? We will be waiting for a good time yet.


there may not be fibre just around the corner, but there is probaby empty conduit running down the street waiting for a fibre to be blown down it without digging up the street again.  once the ftth project is launched i expect telecom, vector and whoever else will be renting out the conduit space wherever they dont have the contract to deploy fibre so it might happen quicker than we think


I doubt that many streets would have empty conduit waiting for fibre, unless their footpaths were recently ripped up by the power company etc (who might have dropped in their own conduit). Vector was talking about running fibre through obsolete gas mains a while ago... Not all councils think that far ahead either, but maybe some have laid conduit in a few streets.




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  Reply # 237747 22-Jul-2009 07:32 Send private message

I dont know what actual contention Telecom use, but I suspect around 50:1 on the bigger ISAM nodes if an imaginary 10Mbps target per user was possible. Telecom should have minimum 2 links to each cabinet for redundancy, maybe in a ring or sharing bandwidth at the exchange. For example, if cabinets were fed by 12-strand cables, they might use 2 pairs for the Telecom node and keep the remaining 3 pairs for access seekers. Also worth noting that different fibre technologies need a single strand or a pair.


Hi yes if you work through the numbers based on 2000 subs on a fully loaded host and set of expansion shelves being fed by a single GigE and an imaginary 10Mb/s per sub, then a 50:1 contention is what you get, so I too suspect that each host gets two feeds, giving a 25:1 if fully decked out which is pretty good for domestic compared to the situation before ISAMs.

I note that all the fibre runs Telecom has installed are either 418 or 216 core, and presumably each cabinet gets a loose tubes worth (12) for its provision, so plenty of room for expansion without resorting to WDM for sometime.

Cheers
Cyril

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  Reply # 237780 22-Jul-2009 09:59 Send private message

Im pretty sure they dont enable the full bandwidth further up in the backhaul, perhaps waiting for their backbone network to get a bit more upgrade so they can provide predictable speeds nationwide after the NGN thing starts. Or maybe waiting for the Southern Cross upgrade so they can generate demand for international.




Qualified in business, certified in fibre, stuck in copper, have to keep going  ^_^

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