SHDSL design

[fouad-zeyad1]

Can i implement this design in real work

[Peter Paluch]

Hello,

Assuming your routers can host up to two G.SHDSL cards, then yes, this network could be implemented as shown in your Packet Tracer topology. Please note that with 4-wire connection, the ordinary G.SHDSL back-to-back connection would operate at approximately 4.608 Mbps at most.

Is there any specific reason why you would want to build your network like this, with back-to-back G.SHDSL connections?

Best regards,
Peter

[fouad-zeyad1]

yes , i want to connect two servers point to point using telephone line, and the distance between two servers are 28 km

Can i implement this using G.SHDSL

[Peter Paluch]

Hello,

yes , i want to connect two servers point to point using telephone line, and the distance between two servers are 28 km

Is it 28 km or 2.8 km? If it is 28 km then unfortunately, this won't work. No DSL technology is capable of operating over such a distance. G.SHDSL can reach to about 6 km and that's about it. In addition, the "telephone line" must in fact operate only as a leased line with no dialing, no ringing, no central office inside, no PCM multiplexing of multiple subscribers, no loading coils etc.

Best regards,
Peter

[fouad-zeyad1]

i mean if i used back to back G.SHDSL using leased line " telephone line" , just 6 km 

i can't increase this distance using the same technology

i want to connect two servers point to point with distance 28 km not 2.8 km

[Peter Paluch]

Hello,

Are you suggesting that you actually have a 28 km - long leased line between the two of your sites? Do you actually own the copper cable, or did you lease it from a service provider? If the line is provided by a service provider, you should ask him about the recommended DCE devices (modems) you are supposed to use on that line. On such a great length, even the service provider would be using signal regenerators to avoid signal degradation, but those regenerators would not be capable of handling frequencies so high as used by DSL, so he needs to tell you what kind of modems would be suitable.

Alternatively, you could try to ask the service provider for a different technology to connect your two sites - perhaps an MPLS pseudowire, avoiding the need for a contiguous 28 km-long line whose signal transmission properties are necessarily poor. It is generally rare nowadays to use copper leased lines at all.

With DSL, there is not much you can do. Even on the length of 6 km, the G.SHDSL would slow down to some 500 kb/s, perhaps even less. You cannot exceed the 6 km length with DSL, and I do not see a way of boosting the signal strenght - I haven't heard about DSL signal regenerators, and even if they existed, I do not see how you would install them at arbitrary points of the leased line whose physical run is not really accessible to you.

I am sorry if I didn't understand you correctly - please have me corrected in that case.

Best regards,
Peter

[fouad-zeyad1]

you mean that just 6 km distance,

if i have two cisco routers 888 ( CPE) , and one Cisco router 1921 (CO)

can i connect the 888 routers together by using 1921 in the middle

i can reach 12 km between two CPE

please correct my idea

[Peter Paluch]

Hi,

you mean that just 6 km distance,

Yes. Between any pair of G.SHDSL interfaces, there can be at most 6 km of direct line, and the performance will still be extremely poor, deep below 1 Mbps.

if i have two cisco routers 888 ( CPE) , and one Cisco router 1921 (CO)

can i connect the 888 routers together by using 1921 in the middle

Yes, you can:

888 --- (leased line, at most 6km) --- 1921 --- (leased line, at most 6 km) --- 888

The 1921 would need 2 G.SHDSL interfaces, the 888 would need just 1 G.SHDSL interface. Keep in mind, though, that depending on the quality of the leased line between these devices, the DSL may not come up at all, or the achieved speeds may be very, very slow. DSL speeds fall down dramatically with the increasing length of cabling, and if the leased line has not been certified by the service provider that it is capable of carrying DSL signalling then it is totally a blind shot.

Isn't there a different connectivity option you could ask your service provider for?

Best regards,
Peter

[fouad-zeyad1]

i have my infrastructure , and i don't need service provider

i know that the SHDSL support to 4.6 Mbps when i am using 4-wire

and i will use ATM interface

Are there any new technology i can use it to connect between the servers?

and if DSL not useful in the previous scenario, what is the perfect scenario ?

[Peter Paluch]

Hi,

Are there any new technology i can use it to connect between the servers?

None that I am aware of. DSL is pushing the absolute limits of what a copper medium can provide. For long-haul connections like the one you need to go through, copper media have long been superseded by fiber and optics. Copper simply isn't suitable for longer distances - it never was. You either have speed, or you have distance, but you cannot have both. G.SHDSL speeds fall down quickly:

https://www.broadband-forum.org/marketing/download/mktgdocs/SHDSL_wp.pdf

I am not sure if sub-1Mbps rates are acceptable to you.

I understand that replacing the copper media with fiber may not be an option for you, but to go over distances that span kilometers or tens of kilometers, using copper media is walking a very thin ice.

I just wonder - you say you have your own infrastructure - what was it originally used for? Are those links some sort of private telephone lines? If so, didn't you need yourself to use some amplifiers or similar devices on such long distances to prevent even plain analog voice from deteriorating?

Best regards,
Peter

[fouad-zeyad1]

thanks for reply

i need to use copper only no fiber

can you help me about DSL amplifier devices 

[Peter Paluch]

Hello,

I am sorry but I have no experiences or knowledge about DSL amplifiers - if there even is such a device for G.SHDSL. In all DSL deployments I have worked with, the local loop (the telephone wiring) was already provisioned by the telco operator, and I was never in a position to extend the reach of an existing local loop.

Unfortunately, I am afraid that what you are trying to accomplish - bridge 28km of distance using DSL - is physically impossible. DSL was designed from its very beginnings as a technology intended to operate on local loops which are at most a couple of kilometers long. No existing reasonable technology, DSL or other, is capable of high speed data transmissions over 28km of unamplified copper wire.

Best regards,
Peter