Multitech RF500S Uživatelský manuál stáhnout pdf (Strana 12)

4.2 Selecting a Provider

Our first attempt was Verizon. Our central office is equipped with Verizon DSL but we did not qualify. No

reason was given but it was probably excessive distance. When I plugged in phone numbers closer to the

CO they qualified. Next we tried to sign up with a business class DSL supplier. We were turned down due

to distance. They estimated we were 20.9K feet from the CO. In retrospect this was lucky because shortly

thereafter they got out of the DSL business.

Next we tried Vitts. According to Vitts we were only 10K feet from the CO. As others have also found out

DSL prequalification distance estimates are all over the place. The only way to get an accurate

measurement is to actually have the line installed. We were concerned the estimate might be too low, but at

least it gave us a chance to get the circuit installed. At worst we would have to settle for a lower speed. We

signed up for HomeReach 530 service. This is their standard business SDSL 528kbp/s business service

with a relaxed service level agreement (SLA). Vitts is interesting because they run a native IP network.

They use Net To Net Technology DSL equipment that runs IP over DSL. IP packets are not converted to

ATM for DSL transmission eliminating overhead. Vitts also acts as the ISP so the supply chain is reduced

to Vitts and Verizon.

4.3 Getting the Circuit Installed

SDSL requires a dedicated line. Vitts handled the coordination with Verizon our Incumbent Local

Exchange Carrier (ILEC). Our outside wiring is 20 years old and has been modified several times. I wanted

Verizon to reduce wiring clutter and rework the Network Interface (NI). I called the local business office

and got a rather quizzical response. They don’t have customers calling to discuss how to install telephone

company wiring. Fortunately I was transferred to the engineering department and discussed my wishes with

a helpful engineer. They agreed what I wanted was reasonable and promised to inform the craftsman when

they were dispatched to install the DSL circuit.

Verizon showed up as scheduled and did a great job updating and cleaning up the wiring. Turns out the

folks that install data circuits are separate from the normal phone installers. Verizon removed about a 1,500

feet of bridge tap. Removing bridge taps improves DSL performance. This is not done for free, it is up to

the DSL provider to request and pay for this service. Bridge taps occur because your phone line is spliced

to the cable running down the road. That circuit may continue for hundreds or thousands of feet down the

road beyond your residence. This extra cable degrades DSL performance. They installed a new six-line

Network Interface device (NID) to replacing a jumble of old lightning protectors and network interface

disconnects.

Vitts showed up a few days later and installed the DSL modem,

which I was admonished to call a Network Termination Device

(NTD). The Vitts Technician connected his laptop to the NTD and

got a solid connection at 528kbps. I was elated. I finally had DSL.

The next morning the line was dead. The NTD indicated it was

unable to sync to the line. Vitts dispatched a tech the following day

to replace the NTD. The line has been flawless ever since.

The NTD converts the DSL line to 10Mbp/s Ethernet. It is connected to the WAN port of a Multitech

RF500 broadband router that interfaces the LAN to DSL. Vitts uses static IP addresses. This provides a

permanent address for as long as I use the service.

Over the last four months I’ve experienced three short outages. They were always internal routing screw

ups within the Vitts network never problems with the local loop.

Total time to get DSL was approximately two months from order entry to going live.

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