Specifications

Disadvantage of Splitter

Installation required

Dedicated run from splitter to DSL modem

Have to purchase separately

4.4 Installation

The Verizon self-install kit included a Westell “white”

modem and install CD. The type of modem varies

depending on your location.

Prior to the activation date Verizon technicians

connect your phone line to the DSLAM at the central

office and create a user account. Verizon uses PPPoE

for log on. This is very similar the way PPP used with

dialup modems. PPPoE requires login to establish a

connection.

When everything is up and running in the central office Verizon sends out a welcome email. At that point

the modem can be connected to the phone line. The Westell modem has four indicators, power, ready, link,

and activity. The power light is on when the unit is powered up. Ready is on after the modem completes is

internal self-test. Link is on when the modem is synchronized to the DSLAM in the CO. The activity

indicator flashes as data moves over the Ethernet connection between the modem and the user’s equipment.

The link indicator indicates the modem is synchronized to the DSLAM; it does not indicate a connection to

the Internet exists. This is a source of some confusion.

Once the connection is activated you need to run the Verizon install CD, even if you intend to use a router.

Verizon requires use of MS PPTP VPN and a customized Netscape browser for initial configuration and

WinPoet for PPPoE, to simulate a dialup connection. I did not intend to use WinPoet as I have a router. I

loaded the Verizon install CD on a spare PC. Install was pretty uneventful. The only annoyance is Netscape

runs in a small window, that cannot be expanded and the Verizon stuff has to be scrolled horizontally and

vertically. When activation is complete a screen with all your account info is displayed, this cannot be

copied or printed directly from the browser. Once the connection was up and running I transferred the

PPPoE setting to my Multitech RF500S router. It logged on without a hitch.

Verizon ADSL has been very reliable with only a few short outages. None of the outages have been

problems with the phone line itself; I’ve never lost the link light. The problems have been Verizon routing

errors or DNS failures. Overall I’m pleased with the Verizon service. My only complaint is the ever-

changing acceptable use policy. Since I signed up Verizon added restrictions on outgoing mail and has

banned use of servers.

4.5 Optimization

There are many urban myths about magical tweaks you can make to improve performance. In general most

of them are nonsense. One thing that makes optimization difficult is that measurements are hard to

duplicate since so many things can change between tests.

The only useful tweaks I’ve found is to adjust the TCP receive window and in some cases to force a

specific maximum packet size. A TCP connection requires the receiver to periodically let the sender know

that everything is OK. This is called the receive window. If the transmitter has not received an

acknowledgement after it has sent a number of packets it stops transmitting and waits. At fast connection

speed, and if the connection adds latency the receive window (RWIN) needs to be increased to prevent

pauses in transmission.

Figure 4 Westell ADSL Ethernet modem