A faster ride

[Herr_SturmGeist]

Telkom is creating more problems than it solves by upgrading the networks to fibre optic systems. First problem is that ADSL or ADSL2+ will not work as they use the (normally) unused frequency spectrum of copper wires this will not work on the fibres as they are digital, this brings up the second problem in that Telkom still uses ATM infrastructure which reduces the capacity of the fibre system compared to an IP based one. Thirdly it would be far easier in the long term if they took the fibres directly to houses as they would then theoretically never have to upgrade again as multiplexing of the fibres will provide all foreseeable bandwidth needs (up to 9.6Gbps). Lastly Telkom used inferior fibre optic cables in this upgrade which means that when they decide to take fibre to the home they would have to replace all of the cables due to signal losses and inferior multiplexing performance.

 

[Roman4604]

Telkom is creating more problems than it solves by upgrading the networks to fibre optic systems. First problem is that ADSL or ADSL2+ will not work as they use the (normally) unused frequency spectrum of copper wires this will not work on the fibres as they are digital

I dont think you quite understand how it all fits together.

Your short range analogue copper line goes to the curb box. In the curb box is a mini ADSL2+ DSLAM with a splitter. The splitter splits the signal into ADSL frequncies which go into the DSLAM connected to the exchange via a fiber pair, while the voice frequncies either carry on to the exchange over copper or go into a voice/fiber TDM mux connected to the exchange via another fiber pair.

The only question is on the data side will Telkom go with IP DSLAMs or ATM DSLAMs. I'm still leaning toward ATM as its too radical change at he moment for them to move IP session & security management out of the core (i.e. from huge centralised ESR routers to mini routers within IP DSLAMs).

So you cant say that ADSL2+ travels over fiber, but the time your traffic is on the fiber its either ATM or native IP (MetroE) already, not ADSL.

this brings up the second problem in that Telkom still uses ATM infrastructure which reduces the capacity of the fibre system compared to an IP based one.

You realise that ADSL uses ATM's 53byte cell packetisation ... it is in essence ATM, just encoded on to an analogue line.

 

[Hades]

The problem is, their 4 meg ADSL is in testing and a fair percentage of the time they have to decrease it to 2 megs or 1 meg. Can they also maintain the bandwidth for ADSL ?

Yeah agreed.

Most of the time during business hours my line will drop to lower speeds due to very low SNR......SNR however increases after hours when biz use drops....

There isn't even enough local bandwidth haha

 

[Herr_SturmGeist]

Your short range analogue copper line goes to the curb box. In the curb box is a mini ADSL2+ DSLAM with a splitter. The splitter splits the signal into ADSL frequncies which go into the DSLAM connected to the exchange via a fiber pair, while the voice frequncies either carry on to the exchange over copper or go into a voice/fiber TDM mux connected to the exchange via another fiber pair.

You are ignoring the fact that as speeds increase on ATM networks it becomes more difficult to perform the packet segmentation and reassembly (also within a reasonable time) and for a Telecoms company this becomes prohibitively expensive at speeds in excess of 16Mbps, added to the problem that fewer virtual circuits and pathways can be handled at these higher speeds. In addition ATM is inheritantly an asynchronous protocol. Worldwide ATM is only considered competitive in speeds below 2Mbps, thus what I am trying to say is that Telkom is reducing the upgrade viability of their network which only leads to more delays and higher costs for the end user.

 

[Roman4604]

You are ignoring the fact that as speeds increase on ATM networks it becomes more difficult to perform the packet segmentation and reassembly (also within a reasonable time) and for a Telecoms company this becomes prohibitively expensive at speeds in excess of 16Mbps .... Worldwide ATM is only considered competitive in speeds below 2Mbps

Err no, only in a 3rd world country like ours is ATM used down to speeds as low as 2Mbps (SAIX min. access). No one uses ATM below 2Mbps as the cell header/content ratio mean you loose a noticible % of your capacity. The average ATM link in S.A. runs at 155Mbps (Oc3) which is considered slow in the rest of the world where the norm is 622Mbps (Oc12).

As ATM fell out of fashion a few years ago, interface speeds havent generally scaled passed Oc12. POS (Packet over SONET/SDH - IP frames encapsulated in PPP instead of packetised into cells) has overtaken ATM as the medium of chose and here interface speeds scale up to 2.4 Gbps (Oc48) and 9.6 Gbps (Oc192).

Going forward native Long-Range Ethernet will take over from POS as the link protocol of choice for NGN backbone links with speeds of 1Gbps, 10Gbps and soon 100Gbps.

 

[ldmelsa]

How is it caped?

How is it caped? - I think Telkom will be able to distinguish between the IPTV data and the Internet traffic. That means they will leave the IPTV data uncapped (obviously), and they will have a cap for Internet usage.
What do you guys think?

56kMan

 

[Paul_S]

How is it caped? - I think Telkom will be able to distinguish between the IPTV data and the Internet traffic. That means they will leave the IPTV data uncapped (obviously), and they will have a cap for Internet usage.
What do you guys think?

56kMan

That is what I think they will do as well.
My modem currently syncs at max speed (~3300 kbps) even though I only have a 384kbps account and it never used to do this before.
They need to have all customers with their lines synced at max speed - if they don't then people with 384kbps connections won't be able to subscribe to IPTV.

So your Internet access speed and cap will be separate from IPTV.

 

[UnUnOctium]

10 meg connection with a 3 gig cap, nope, not excited at all.

+1

 

[Tns]

i wonder what the catch will be here

 

[MyDraadloos]

10MB connection and 3GB cap ....... sounds about as usefull as a supercar on 100m of tarred road.

 

[magneto]

u have 2 pay more..