How media converters can be used to resolve networking
problems and save money
Computer networks have
evolved into an indispensable asset for corporations around the world.
These complex systems of cables, jacks, patch panels, switches, routers,
and servers provide the foundation for the communications of our global
economy. Many corporations view their networks as a strategic advantage
over their competition and focus on constant improvement in performance
of their networks.
managers yearn for the latest equipment and higher speeds, budgetary
restrictions impose limitations and precipitate a less than homogenous
network. Inevitably, network administrators must contend with a variety
of protocols, speeds, and media in their networks. Media conversion
technology was developed to address these problems and has evolved from
a stop gap technology into an a technology that offers network
administrators new choices for deploying fiber optics into their
networks cost effectively.
Very simply stated,
conversion technology enables connections of disparate media (cabling)
types in networks where non-homogeneous cabling exists. Most commonly,
media converters are used where UTP (un-shielded twisted pair) copper
cabling and fiber optic cabling coexist in a network cabling plant.
Less common, but also available, media converters are also used where
legacy cabling types such as Coaxial or Twinaxial cabling must be
integrated with UTP or fiber optic cabling. Converters exist in a
variety of form factors, which are standalone, multiport, and modular
chassis. These different physical forms address the various
applications that exist.
Media converters are
protocol specific, meaning that you need to have an Ethernet converter
to convert 10BASE-T to 10BASE-FL. Furthermore media converters do not
convert protocols, such as Token Ring to Ethernet. However, media
converters do exist for a broad range of protocols including Ethernet,
Fast Ethernet, Gigabit Ethernet, Token Ring, T1, DS3, RS232, RS485,
V.35, X.21, analog phone lines, video, and much more. This article will
show some examples of how media converters are used in a variety of
networks and explore how utilizing media converters can be a
Typical Applications for Media Converters
(back to top)
Enterprise networks come in variety of sizes and configurations. Some
consist of large multi-building locations; others are small flat
networks. In this section, we will explore some of these various
network layouts and how media conversion can be utilized to save
A LAN (local area
network) is generally defined as the interconnection of multiple
devices such as servers, PCs, printers, etc. in a confined geographical
area (most often within the same building). LANs can vary in sizes,
ranging from fewer than five users ( peer-to-peer network) to hundreds
or even several thousand users (client/server network). As networks
grow, users are located beyond the reach that copper cable offers.
Network managers are placed in a position of adding an additional
communications closet near the new users and back hauling fiber to the
central data closet, or running fiber to the desk or work group. A
network manager must either buy a new switch or blade with fiber
interfaces or he/she can use existing equipment with copper ports and
utilize media converters.
The network manager
may have existing ports on a copper switch that could be used with a
media converter to drive the data to the user. A multimode 100Mbps
converter can be purchased for less than $200. Furthermore, 10/100
switches are widely available and can be very inexpensive depending on
the manufacturer and the features that are included. The port density
is much higher for the copper based switches and the cost is
significantly lower. A 10/100 switch will cost a few hundred dollars,
where a 100Mbps fiber switch will cost several thousand dollars. So it
is not hard to see where media converters can offer some cost savings
if you need to run fiber to certain users.
In smaller networks,
fiber is not often required, however, occasions due arise where fiber
may be needed. A service provider could have their demarcation point,
the location where they run the cable to the building, too far away
from a company's data closet. For example, if a small company is
receiving Ethernet service from their Internet service provider and the
demarcation point is placed on the other side of the building complex,
standalone 10BASE-T to 10BASE-FL converters can be used back to back to
extend the data connection to the company's data closet on the other
side of the building complex.
The LAN backbone allows lower capacity portions of the network to be
aggregated into higher capacity connections to optimize throughput
across the entire network. For example, in a multi-story building you
may have workstations and printers connected to a small 10Mbps hub for
a given work group. This hub may be connected into a 10/100 dual speed
switch in the wiring closet of the building that is in turn, connected
to another switch in the main data center via a Gigabit up-link port.
The connection between these two switches would serve to aggregate the
multiple, relatively low bandwidth users, from the 10Mbps hub into a
high bandwidth 1000Mbps connection to the data center for efficient
access to servers, storage devices, etc. that may be shared by many
users throughout the organization.
Media converters are
often used in backbone connections to facilitate the disparity between
media types being used. Many times converters are used to enable the
interconnection of devices such as switches and servers with copper UTP
interfaces to multi-mode fiber optic cabling that is commonly used in
network backbones. Multi-mode fiber is quickly becoming the media of
choice in many network backbones because it accommodates longer
transmission distances than its copper counterparts (UTP copper cable
is limited to 100 meters where multi-mode fiber can go as far as 2000
meters without repeaters). Fiber can support higher speed protocols
available now and for several years to come. Also, fiber optic cable is
impervious to EMI (electromagnetic interference) as well as security
breaches (cannot easily be tapped into and monitored remotely).
The most common
applications for media converters in a network backbone are the
connection of either two switches, or a switch and a server with copper
interfaces across multi-mode fiber interfaces (see figure 1).
Medium-to-large size companies can benefit by using a Chassis-based
conversion solution in the data center and stand-alone or managed
remote media converters on devices such as switches and hubs that may
reside in multiple wiring closets. In cases where more than one
protocol may be present (i.e., Ethernet, ATM, TI/El, etc.), the modular
conversion center can support multiple protocols in a single chassis.
This co-mingling of protocols in a modular system offers cost savings
because the network manager can purchase one platform, yet support
fiber interfaces for disparate protocols. In backbone applications the
port density is not high and the network manager does not want to
invest in equipment with multiple ports if most of the ports will go
A campus environment is typically a group of buildings connected
together via an extended LAN. The LAN commonly has a central location
(data center) located in one of the buildings which houses shared
devices such as servers, storage devices, etc. LAN connections are made
between the central building and devices such as switches, PBXs,
CSU/DSUs to other buildings. The media used almost exclusively for
interconnecting buildings in a campus is fiber optic cabling. Fiber is
used to connect buildings in a campus environment primarily because of
its ability to allow data transmission over long distances and because
of its resilience to the elements and EMI in outdoor environments
(see figure 2).
Figure 2: Campus Environment
buildings can be viewed as extended backbone connections in a LAN. As
with the backbone examples given earlier, typically media converters
are used to facilitate the connection of the fiber optic cabling and
copper interfaces on switches, etc. located in the various locations.
Typically campus LANs are relatively large (several hundred or even
thousands of clients) and they also often must support multiple
protocols. Large networks with multiple locations also have a greater
propensity to require some form of SNMP management for active devices
for efficient resource allocation and troubleshooting capability from a
central location. Unique requirements of a campus LAN lend themselves
well to modular chassis conversion platforms.
In the example above, remote devices in outlying buildings are
connected back into the data center via fiber with the interconnection
between disparate copper and fiber interfaces facilitated by modular
converter chassis in each of the locations. Another way that media
conversion can offer a cost savings is by helping to troubleshoot and
configure networks that are in a remote location. When network managers
need to support remote facilities often times there is not someone in
that location knowledgeable about networks. Transition Networks offers
several products that allow network managers to manage the remote
converters as well as the chassis based products located in a data
center. With products such as Transition Networks Management
Aggregation Converter for Fast Ethernet, the network administrator can
troubleshoot problems or modify settings without making a trip to the
remote site. While this may be less tangible than a savings in hardware
cost, saving time is no less important when looking at the total cost
of running a network.
Other protocols can also be accommodated in a campus environment.
TI/El connections from the demarcation located in the data center can
be extended out to other campus buildings to allow voice (PBX) or data
(CSU/DSU) extensions. The remote end can also be managed as some T1/E1
converters have built-in remote management capabilities. Protocols
commonly used in campus environments such as Ethernet, fast Ethernet,
gigabit Ethernet, ATM, DS-3, etc. can all be supported by existing
The horizontal portion of the network is commonly where devices such
as printers and workstations are connected to a given network. A good
example of this would be a multi-story building where the data center
is located on the first floor and is connected to wiring closets on
upper floors via a high-speed backbone connection. In each of these
wiring closets would reside a switch. Switch ports are connected either
directly to devices such as workstations or may be connected to work
group hubs that are in turn, connected to the workstations. The point
from the wiring closet switch to the devices on a given floor in this
building would be referred to as the horizontal portion of the network.
Smaller networks may be "flat networks" that do not require a backbone
to aggregate bandwidth. In smaller networks the entire network can
typically be considered horizontal.
Conversion technology is used in horizontal networks where fiber optic
cabling must be used for distance extension, EMI considerations or in
some cases, for security reasons.
An example of an application for chassis-based conversion in a
horizontal network to overcome a distance issue would be a large
distribution or retail facility where devices such as workstations,
printer, scanners or cash registers are further than 100 meters from
the data center. A media converter chassis would be used in the data
center to facilitate the copper-to-fiber connection to the switch. On
the remote end, a stand-alone converter would be used to convert the
copper and fiber media.
(see figure 3)
Figure 3: Point System - Connecting Remote Devices
There are also
instances in a large factory where you may have to connect devices
where the cabling must run through the manufacturing facility (see
figure 4). Some factory environments have equipment that may produce
significant levels of EMI ( electromagnetic interference). This EMI can
have adverse effects on data transmitted across copper based cabling.
In these cases, fiber optic cabling would be used in areas where EMI is
an issue (fiber optic cables are impervious to EMI). Media converters
would be used at either end of the fiber optic cable to allow for the
connection of fiber-to-copper interfaces. A chassis-based conversion
platform works well in situations where multiple cables need to be
converted from copper to fiber. In industrial environments, many
different protocols may be present as well. Industrial automation
equipment use everything from Ethernet to RS232/485/422 to ARCNet for
different operations. Multiple connections as well as multiple
protocols can be easily accommodated by media conversion chassises or
in a rack for standalone converters. A chassis solution offers the
option of remote SNMP management; which can prove useful in industrial
environments where devices may not be accessible during factory
operations or may be inconvenient due to distance or location.
Figure 4: Point System - Industrial or POS Application
The use of fiber
optic cabling to interconnect devices in networks where classified
information is transmitted has been rapidly increasing in popularity.
Government subcontractors working on highly classified projects are
required to transmit any data that moves from a secured area (red zone)
through an unsecured area (blue zone) over fiber optic cabling and
encode it. The reason for this is simple, fiber optic cabling does not
emit an electronic signal (emits light pulses) that could potentially
be monitored remotely nor can it be tapped into without detection.
Stand alone converters or fiber NIC cards are commonly used on the
workstations and are aggregated back into a converter chassis at the
data center or wiring closet.
Not as popular, but slowly gaining in popularity, is fiber to the
desktop. The cost of fiber interfaces, and therefore the cost of fiber
to the desktop, is still perceived by most as too expensive and
currently not a necessity. However, there are documented studies that
have demonstrated that fiber to the desk may be, in fact, a low-cost,
long-term solution (see figure 5). Fiber can eliminate the need for the
intermittent wiring closets (fiber can be run all the way from the data
center to the workstation). These studies contend that fiber will
eventually be required at every desktop at some point due to bandwidth
requirements (fiber can support high bandwidth transmission over
greater distances). The useful life of a fiber cabling plant is
expected to exceed 20 years while the copper infrastructure may be
useful for only the next 5 to 10 years, according to these studies.
High-density conversion technology products offer additional cost
savings and convenience to this argument for fiber to the
The onslaught of single-mode fiber being installed in virtually every
available right-of-way has given much access to fiber between remote
locations in most major cities. Commonly referred to as "dark fiber"
this installed fiber can be leased for the purpose of effectively
extending your LAN (local area network) over distances up to 80
Kilometers (see figure 6). This metamorphosis of the LAN from a
relatively limited geographic location (within a building or a local
campus) to a significantly expanded area is referred to as a MAN
(metropolitan area network).
Figure 6: MAN (Metropolitan Area Network)
significant advantages to a MAN when compared to the alternative, a WAN
(wide area network). MANs allow communication between network equipment
using native protocols such as Fast Ethernet, Gigabit Ethernet or ATM.
In contrast, WANs require conversion from native LAN protocol to a
protocol offered by a given carrier/service provider. This requires the
use of a network router to deal with conversion between the disparate
protocols. This is typically more expensive for the service provided
and also reduces the throughput (100Mbps or Gbps traffic must be
transmitted across slower speed WAN protocols like T1/E1 at no more
than about 2 Mbps).
advantage is that MAN provides far more control of the connection for
end to end. With a MAN, you have complete control of the communication
process. This includes the ability to remotely manage, monitor and
perform diagnostics yourself in comparison to the WAN connection in
which you must rely on your service provider to manage and maintain the
link between you and your remote office.
technology allows common native network protocols to be delivered over
distances that can traverse most major metropolitan areas. The two most
common network backbone protocols, Fast Ethernet and Gigabit Ethernet,
can be transmitted as far as 80 km (65km for Gigabit). Long haul
options are also available for T1 DS3, ATM and others. Again,
chassis-based conversion technology is capable of handling multiple
protocols and multiple interface types in a single modular
Service providers are companies that offer Internet services to
companies or facilitate the data connections of large corporations with
operations in a wide variety of locations. Additional certifications
can be required by service providers such as Network Equipment Building
Systems (NEBS) or FCC Class B. To address this market, media converters
have designed their equipment to meet these more rigid
FCC class B refers
to emissions requirements in North America and CISPR class B is
effectively the international equivalent of FCC class B for
installation of electronics in residential environments (see figure 7).
Many carriers for any active electronics device installed in a CO
(central office location) require NEBS level 3 certification.
Figure 7: Data
Services: Fiber to Multi-Tenant Dwelling / Fiber to the Home
In recent years
access to the worldwide web has found it way into the homes of
literally millions of people around the globe. As more people access
the Internet and place greater demands on the type of content they
would like access to, the bandwidth requirements of users have
increased as well. Many people, frustrated with slow web access via
dial-up POTS (plain old telephone) connections have begun demanding
higher speed Internet access. Service providers have offered several
solutions to increase the access speed of their customers with
technologies such as DSL, VDSL and cable modems. Recently, service
providers have started turning to tried-and-true network LAN protocols
such as Ethernet as a solution for their customers, bandwidth
A common use for
conversion technology in a residential application is enabling the
conversion of copper to fiber optic cabling for distance extension from
a service provider's central office to a multi-tenant dwelling.
High-speed data services are delivered to the basement of these
building via fiber and are distributed via copper to clients living in
these structures. Clients are able to gain access to the Internet at
10Mbps Ethernet speeds or faster. This (in contrast to 2 Mbps or
slower) is the highest speed offered by the majority of providers
conversion systems are used on both the service providers' end as well
as on the clients side. The modular design of the chassis enables the
service provider to easily add connections and also upgrade easily and
inexpensively. Chassises are also designed to occupy a relatively small
amount of space, which is often at a premium at both sides of the
connection. Chassises also provide remote management capability that
can significantly reduce costs with less frequent need to dispatch
personnel to a customer site. Lastly, chassis offer redundant power
options which improves customer satisfaction (less down time) and
reduces operating costs by eliminating service calls to remote
The examples above show the need for implementing fiber into networks.
Sometimes the entire network design is done from the beginning, other
times fiber is added gradually as needed. Regardless of when fiber is
implemented, network managers are faced with purchasing network gear
with fiber interfaces. Networking switches and routers with fiber
interfaces are significantly more expensive than their copper port
counter parts. This is due largely to higher component costs and lower
volumes. These devices are also a much less dense solution than copper
port devices, although small form factor (SFF) optics have made
significant improvements in this area. Network managers will find it
cost effective to utilize switches with copper ports used with media
converters versus purchasing a new switch with fiber ports.
To illustrate this
point let's look at a few examples.
A network manager has to add a new department with 24 users. These new
cubes extend beyond copper's reach from the data closet so fiber must
be deployed. In this example, we will explore two options. The first
option would be to use 2 Cisco Catalyst 2912 switches with 12 100Mbps
FX ports. The second option would be to use 1 Cisco Catalyst 2950
switch with 24 10/100TX ports and Transition Networks Point System
Chassis and 100Mbps converters.
Cisco 2912, model number WS-C2912MF-XL has 12 100Mbps FX ports and has
a unit cost of $5516.75. Two of the Cisco 2912 units would be needed to
support 24 users and would have a total cost of $11033.51, or a cost of
$459.73 per port.
Cisco 2950, model number is WS-C2950-24 has 24 10/100Mbps TX ports and
has a unit cost of $762.84. Transition Networks 19 Slot media
conversion chassis, model number CPSMC1900-100 has a unit cost of
$406.55. Transition Networks Fast Ethernet Multimode media converter,
model number CFETF1013-105 has a unit cost of $207.02.
For this option the
network manager would need to purchase one Cisco 2950 switch, 2
Transition Networks 19 slot chassises, and 24 Transition Networks Fast
Ethernet converters for a total cost of $6,544.51 or a cost of $272.69
PS & Cisco
A service provider is delivering 100Mbps service to 48 customers in a
multi-story building. Because the services are homogenous the service
provider decides to evaluate a multi-port converter. The service
provider is bringing data to the basement of the building and then
running fiber to each floor to deliver the data. The service provider
has selected the Enterasys Smart Switch 2200 series and must choose
between the 16 port 100Mbps FX switch or the 24 port 100Mbps 10/100Mbps
TX switch coupled with the 12 port 100Mbps converter from Transition
Enterasys Smart Switch 2200 series model number 2H258-17R with 16
100Mbps FX ports. To support 48 users the service provider must
purchase three of these units at a total cost of $30,067.94 or $626.42
The service provider would use the Enterasys Smart Switch 2200 series
model number 2H252-25R that has 24 10/100 TX ports. These switches
would then be used with a 12 port 100Mbps FX media converter from
Transition Networks; model number UFETF1013-120. Because there are 48
users the service provider would need to purchase two of the 24 port
switches and four of the 12 port media converters.
The total cost of
the two switches would be $7,681.68 or $160.04 per user. The total cost
of four media converters would be $11, 477.68 or $239.12 per user. The
total solution cost would be $19,159.36 or $399.15 per user.
In both of these examples, a standalone media converter would be used
at the customer's location to convert from fiber back to copper.
Because the standalone converter would be used in either option of both
scenarios, it does not effect the cost savings calculation.
Enterasys 16 FX
Media Conv &
24 TX Port
In both examples
above, every port is being used on the fiber switches. This optimal
case does not usually occur in actual applications, and while the total
cost of the fiber switches does not change, the cost per user does
change. Furthermore, if a chassis-based solution is used the service
provider will incur the cost of the chassis, but can add media
converters as necessary. This not only saves money, but also provides
flexibility if the service provider needs to add a single mode card or
add a different converter.
Another advantage of
media converters is the various distances that are available. Typical
fiber blades come with multi-mode optics. While users can choose from a
wide variety of distances to extend the reach of their network up to
100km in some cases.
have evolved from their initial intent of adding one or two fiber
strands to a network as a quick resolution to a problem. Today, media
converters are offered in a wide variety of form factors to address the
complex needs of network managers. Conversion systems now offer
management software that allows the network manager to fully monitor
and configure the systems. Converters can be deployed in a wide variety
of network applications such as small local area networks, large
enterprise networks, and service provider networks. Not only do media
converters provide unique solutions for difficult problems, they offer
flexibility and cost savings when implementing fiber into your network.
Media converters are networking hardware elements that need to be
considered when designing a network.