Class of 2011
ShipleySystems, LLC DSL Nuts and Bolts
High Speed Access takes the form of a specially engineered Phone line, TV
Cable, or Wireless connection. This guide is broken up into sections so that you
can jump to the topics that interest you now. The bottom of this guide provides
a glossary of terms. Click on a topic below, or read to your heart's content.
:::. DSL (Digital Subscriber Line)
uses an ordinary copper phone line, but is subject to distance restrictions and
line quality requirements. Distance, as measured in total cable length from the
Telephone CO to your
location, is limited to 20,500 feet for the lowest data rate. The closer you are
to the CO within this range, the higher the rate you can get. This distance
figure is not your distance "as the crow flies". The telephone cable running to
your area does not travel in a straight line from the CO to you, it may in fact
run to another area, and then run to your area.
Line quality and line integrity are also limiting factors. If a
pair gain unit, or
appear anywhere on the line you will be unable to order DSL from most
providers. Some providers will agree to condition the line so that you may order
the service, in exchange for a contract term of one year or more.
The basic questions, assuming you qualify for DSL service, are:
- How much bandwidth do you need?
- Are you an end user or a provider?
- How many computers are you connecting to the Internet?
The bandwidth question can be a little tricky to answer. A single computer
used for casual Internet use can certainly use a 256k without any doubts.
ShipleySystems, LLC has many business offices, including Travel Agencies,
Insurance Agencies, Law Offices, and Banks, that have up to 14 computers
networked to a single 256K DSL connection. As long as the users are not engaged
in heavy downloading or file transfers this is not a problem; 256K is more than
adequate. However, if some users on the connection are going to be doing heavy
file transfers or regularly streaming audio or video content, it may be wise to
consider a higher bandwidth DSL interface. Upgrading the bandwidth on Qwest DSL
costs only $30.
An End User is an Internet user who does email, web surfing,
and downloading or uploading of files to other servers. A Provider
runs a server (a computer that provides services such as email, web, FTP, or
file sharing services to other users on the Internet). If you are a provider,
you may wish to consider a higher bandwidth.
ADSL versus SDSL :::. ADSL is
Asymmetric Digital Subscriber Line, where the Downlink bandwidth is higher than
the Uplink bandwidth. This type of service is just fine for the end user,
because they spend most of their time downloading (or receiving) data. A
Provider spends most of it's time uploading (or serving) data to other systems.
SDSL is Symmetric, meaning that the rated bandwidth is equal for both uplink and
downlink. Determining what bandwidth a provider may require is beyond the scope
of this article. Tucumcari only has ADSL.
Router versus Modem :::. Some
DSL services allow you to select between a
router or modem. A
router is more expensive than a modem, but it gives you options, flexibility and
even services, that a modem will not provide. A DSL modem is intended to connect
a single computer to the DSL connection. It is possible to set that single
computer up as a Gateway machine that will route requests from other computers
on your network, but this requires some skill. A modem connection is a direct
connection, in the sense that the IP address assigned to the connection is the
IP address of the computer on the network. This makes it easier for a malicious
hacker to get direct access to your machine. A router uses
NAT, so that network
requests are translated through the router as a gateway. A hacker might gain
access to the router itself, but you may shut off the vulnerable services (web,
TELNET, FTP) so that is would be difficult or impossible to tamper with your
system. If you have a several computers networked together via TCP/IP,
connecting a DSL router to the hub or switch on your network will provide
seamless Internet connectivity for all. If you have a larger network of
computers, many of the routers even provide
DHCP service for
automatic allocation of addresses on your network. This simplifies your network
configuration and management.
For the end user, the simplicity and lower cost of a modem often makes sense.
For the provider, or for anyone connecting a network of end users to the DSL
connection, the router is the very best investment.
:::. IP, Network Addressing. Most DSL
services in New Mexico use dynamic
assignment. An Internet service provider does not need to have a unique IP
address for every customer. Since not all customers are connected to the network
at once, IP addresses are handed out as needed, from a pool of addresses that
are not currently in use. Some connections require a static IP address; the same
address at all times, so that the computer may get access to systems on the
other side of a firewall, or so that other users may access the system from the
Internet. ShipleySystems, LLC can provide a single Static IP address, or a CIDR
block of addresses if needed. A single static IP is available for $5.00
Please submit your request for a static IP or CIDR to
ShipleySystems, LLC. If you
need help determining your needs, please call our Tech support number.
Charges for Additional IP Addresses :::.
All requests for additional IP addresses must follow ARIN (American Registry of
Internet Numbers) guidelines as shown at:
Requests for additional IP addresses may require Customer to renumber from
previously issued IP address space to conform to accepted routing guidelines.
All pricing for IP addresses is subject to change.
Please submit your request for a static IP or CIDR to Requests. If you need
help determining your needs, please call our Tech support number.
- Asymmetric Digital Subscriber Line. The download speeds are different than
the upload speed.
- Asynchronous Transfer Mode. A high speed “shared” transport service
offered by US West and other phone companies that allows voice, video, and
data services to be simultaneously carried over the same physical lines.
ATM Cell Cloud
- ATM services are typically made of multiple ATM switches, also referred to
as an ATM Cell Cloud. DSL service provides the transport from the customers
site to the ATM Cell Cloud based on the
Qos being purchased.
Leased line services between ShipleySystems, LLC and the ATM Cell Cloud
provide high speed transport to the ATM Cell Cloud based on a
- A bridge is a product that connects a local area network (LAN) to another
local area network that uses the same protocol (for example, Ethernet or Token
Ring). You can envision a bridge as being a device that decides whether a
message from you to someone else is going to the local area network in your
building or to someone on the local area network in the building across the
street. A bridge examines each message on a LAN, "passing" those known to be
within the same LAN, and forwarding those known to be on the other
- Bridge Tap refers to line that is cut short but continues to be physically
connected to the pairs that continue beyond the new termination point. Think
of a "T" intersection on a road.
- Committed Bit Rate. Its an
Qos (quality of
service) that guarantees delivery of the speed being contracted for on
communication services. For example, if purchase a 256k service, under CBR
you are guaranteed 256k based on the Qos being provisioned in the ATM cell
- A routable block of IP addresses, (Classless Inter-Domain Routing)
assigned by your network provider (in this case, ShipleySystems, LLC) so that
your systems may communicate with, and be available to, other systems on the
CO (Central Office)
- The Telephone Central Office is a facility where the switch equipment that
switches phone calls is located. Most towns have several of these facilities,
and large towns have many.
- Customer Premises Equipment.
- DHCP (Dynamic Host Configuration Protocol) is a protocol that lets network
administrators manage centrally and automate the assignment of Internet
Protocol (IP) addresses in an organization's network.
- Digital Subscriber Line. A phone company offering that allows up to 7.0
Mbs of bandwidth to be utilized over a single traditional phone line. The
typical offering for both practical and technical reasons is generally in the
144k to 768k range. Like ISDN, this service requires substantial equipment
investment by the phone company and has even more stringent distance,
quality-of-line, and equipment restrictions. Most phone companies are making
this service available only in densely populated, higher income areas. DSL is
an ATM service, i.e. all DSL traffic uses ATM encapsulation.
- Digital subscriber lines access multiplexer. This is the gizmo that allows
your phone line to carry both voice and data by splitting the voice and data
- Gauge is the measure of the circumference (or thickness) of wire. The AC
wiring in your home is 14 or 16 gauge, whereas phone wire is 24 or 26 gauge
(the bigger the number, the smaller the wire). Telephone wire is terminated on
blocks of metal pins where it comes out of a large cable (200-600 pairs of
wires), where it then runs on smaller cables to individual blocks or
buildings. If different gauge wire was used from one cable to the next, DSL
service is not possible: different gauge wires have different impedance (or
resistance) characteristics, and this makes DSL signaling impossible.
- In order to communicate and exchange data through a network, each computer
must have a unique address. IP addresses are numeric assignments in the form
of four blocks of numbers, e.g. 188.8.131.52.
- Also called Voice coils, these inductive devices used to be installed on
weak phone lines in order to boost the loudness of frequencies in the range of
the voice. On voice-only circuits the benefit is obvious. On modem and data
circuits this device cuts the data rate of the connection. These devices are
no longer used, but may be present on older lines, especially in areas that
are distant from the CO.
- The local loop is the facility (wire) between the phone switch and the
customers location (i.e., house, office, etc.). The local loop is also
referred to as “The Last Mile.”
- In order to DSL to work a customer must have a local loop that can qualify
(loop qualify) for the service being ordered by the customer. One of the
limiting factors is the distance factors based on various speed ratings. There
are other line quality issues that can prevent a line from loop qualifying. An
example is bridge tap.
- NAT (Network Address Translation) is the translation of an Internet
Protocol address (IP address) used within one network to a different IP
address known within another network. One network is designated the inside
network and the other is the outside. Typically, a company maps its local
inside network addresses to one or more global outside IP addresses and
translates the global IP addresses on incoming packets back into local IP
- Pair Gain devices are used to increase the number of telephone circuits
available without laying additional cable. If an area is running out of copper
pairs for telephone circuits, pair gain units may be installed to multiply the
number of lines. A pair gain unit is an analog to digital device that takes 2
or more phone wires, converts them into data signals, and runs them through a
single phone line back to the CO. Pair gain devices typically limit the modem
connection to 28,000Kbs or less.
- A PVC (Permanent Virtual Circuit) is a software-defined logical connection
in a frame relay network. A feature of frame relay that makes it a highly
flexible network technology is that users (companies or clients of network
providers) can define logical connections and required bandwidths between end
points and let the frame relay network technology worry about how the physical
network is used to achieve the defined connections and manage the traffic.
- Quality of service, i.e.,
- A router is a device that determines the next network point to which a
packet should be forwarded toward its destination. The router is connected to
at least two networks and decides which way to send each information packet
based on its current understanding of the state of the networks it is
connected to. A router is located at any juncture of networks or gateway,
including each Internet point-of-presence.
- Symmetric Digital Subscriber Line. The download speeds are the same as the
- Uncommitted Bit Rate. Its an
Qos (quality of
service) that as no guaranteed delivery of the speed being contracted for on
communication services. For example, you may purchase a 256k service, however,
under UBR there is zero guarantee that you will see 256k based on the Qos
being provisioned in the
ATM cell cloud.