Applying Standards in Data Center Network Design
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Transcript of Applying Standards in Data Center Network Design
PAGE 8 SEPTEMBER 2009 www.cablingbusiness.com
DATA CENTER SPACES AND INFRASTRUCTURE
The main elements of a data center,
defined by TIA-942, are:
Entrance room (ER): The space
used for the interface between data
center structured cabling system and
inter-building cabling, both access
provider- and customer-owned. The
ER interfaces with the computer room
through the MDA.
Main distribution area (MDA):
Includes the main cross-connect,
which is the central point of distribu-
tion for the data center structured
cabling system and may include a hor-
izontal cross-connect when equipment
areas are directly served from the
MDA. Every data center shall include
at least one MDA.
ogy advancements in system equipment
must be considered.
TIA-942, Telecommunications
Infrastructure Standard for Data Centers,
was released in April 2005. The pur-
pose of this standard is to provide
information on the factors that should
be considered when planning and pre-
paring the installation of a data center
or computer room. TIA-942 combines
within a single document all the infor-
mation specific to data center applica-
tions. This standard defines the tele-
communications spaces, infrastructure
components and requirements for each
within the data center. Additionally, the
standard includes guidance as to rec-
ommended topologies, cabling dis-
tances, building infrastructure require-
ments, labeling and administration,
and redundancy.
When designing a data cen-
ter, several factors should
be taken into consideration,
including standards compliance. TIA-
942, Telecommunications Infrastructure
Standard for Data Centers, details several
of the factors that should be considered
when designing a data center. When
implementing a structured cabling solu-
tion, the standard recommends a star
topology architecture to achieve maxi-
mum network flexibility. TIA-942 outlines
additional factors crucial to data cen-
ter design, including recognized media,
cable types, recommended distances,
pathway and space considerations, and
redundancy. In addition to standards
compliance, the need for infrastructure
flexibility to accommodate future moves,
adds and changes due to growth, new
applications, data rates and technol-
DATA CENTER TECHNOLOGY
Applying Standards in Data Center Network Design
By David Kozischek
PAGE 10 SEPTEMBER 2009 www.cablingbusiness.com
Horizontal distribution area
(HDA): Serves equipment areas.
Equipment distribution area
(EDA): Is allocated for end equipment
and shall not serve the purposes of an
ER, MDA or HAD.
Telecommunications room (TR):
Supports cabling to areas outside the
computer room and shall meet the specifi-
cations of ANSI/TIA569B.
The components of the cabling infra-
structure, as defined by TIA-942, are as
follows:
– Horizontal cabling
– Backbone cabling
– Cross-connect in the ER or MDA
– Main cross-connect in the MDA
– Horizontal cross-connect in the TR, HDA, MDA
– Zone outlet or consolidation point in the ZDA
Figure 1
Figure 2
– Outlet in the EDA
In a data center including HDAs, the
maximum distance allowed for horizontal
cabling is 90 m, independent of media
type. With patch cords, the maximum
R educed Data C enter T opology
O�ces , Ops . C enter, S upport
R ooms
Ac ces s P roviders
Main Dis tribution Area(R outers , B ackboneLAN/S AN S witches ,P B X, M13 Muxes )
Zone Dis t Area
E quip Dis t Area(R ack/C abinet)
E quip Dis t Area(R ack/C abinet)
C omputerR oom
Horizontal
C abling
R educed Data C enter T opology
O�ces , Ops . C enter, S upport
R ooms
Ac ces s P roviders
Main Dis tribution Area(R outers , B ackboneLAN/S AN S witches ,P B X, M13 Muxes )
Zone Dis t Area
E quip Dis t Area(R ack/C abinet)
E quip Dis t Area(R ack/C abinet)
C omputerR oom
Horizontal
C abling
Horizontal
C abling
channel distance allowed is 100 m, assum-
ing 5 m of patch cord at each end of the
channel for connection to end equipment.
When a ZDA is used, horizontal cabling
distances for copper may need to be
reduced (Figure 1).
DATA CENTER TECHNOLOGY Applying Standards in Data Center Network Design
Blog at www.cablingbusiness.com/wordpress SEPTEMBER 2009 PAGE 11
Applying Standards in Data Center Network Design DATA CENTER TECHNOLOGY
Depending on the type and size of
the data center, the HDA may be collapsed
back to the MDA. This is a typical design
for enterprise data centers. In this scenario,
the cabling from the MDA to the EDA, with
or without a ZDA, is considered horizontal
cabling. In a collapsed design, horizontal
cabling is limited to 300 m for optical fiber
and 90 m for copper (Figure 2).
LOGICAL TOPOLOGIES FOR DATA CENTERS
While standards help guide the data
center physical infrastructure, the logical
data center infrastructure does not have
a standards body helping with design.
Logical architectures, as shown in Figure
3, vary based on customer preference and
are also guided by the electronics manu-
facturers.
Though a standard does not exist, there
are some common architecture best prac-
tices that can be followed. Most logical
architectures can be broken into four layers:
Core
Aggregation
Access
Storage
Core
The core layer provides the high-
speed connectivity between the data cen-
ter and the campus network. This is typi-
cally the area where multiple ISPs provide
connections to the Internet.
Aggregation
The aggregation layer provides a point
where all server area devices can share com-
mon applications such as firewalls, cache
engines, load balancers and other value-
added services. The aggregation layer must
be able to support multiple 10G and 1G
connections to support a high-speed switch-
ing fabric.
Access
The access layer provides the
connectivity between the aggregation
layer shared services and the server farm.
Since additional segmentation may be
required in the access area, three different
segments are needed:
Front-end Segment – This area con-
tains web servers, DNS servers, FTP and
other business application servers
Application Segment – Provides the
connection between the front-end servers
and the back-end servers.
Back-end Segment – Provides con-
nectivity to the database servers. This seg-
ment also provides access to the storage
area network (SAN)
Storage
The storage layer contains the Fiber
Channel director and other storage devic-
es such as magnetic disc media or tape.
TIA-942 Physical Architecture Area
Logical Architecture Area
MDA=Main Distribution Area
Maps to Core and Aggregation
HDA=Horizontal Distribution Area Maps to Aggregation
ZDA=Zone Distribution Area
Maps to Access and StorageEDA=Equip Distribution
area
Figure 4
Figure 3
MAPPING LOGICAL ARCHITECTURES TO TIA-942
The key for many data center design-
ers is how to translate the many logical
topologies onto a TIA-942 structured cabling
infrastructure. This translation will affect some
of the key design elements of a structured
cabling solution such as fiber counts, hard-
ware considerations and physical cable runs.
The first step is to translate the TIA-942 areas
(MDA, HDA, ZDA, EDA) to the logical archi-
tecture areas (core, aggregation, access,
storage). Figure 4 shows a comparison
between the two.
The next step is to take an example
PAGE 12 SEPTEMBER 2009 www.cablingbusiness.com
logical architecture and translate it to a
TIA-942 structured cabling solution. In this
example, we will use a small data center
and map the logical architecture shown in
Figure 5 to the physical architecture of the
data center (racks and cabinets) shown in
Figure 6. The next step is to choose the
TIA-942 architecture that will best map to
the logical architecture shown in Figure 5.
Since this data center is small, a reduced
TIA-942 architecture will be implemented.
In this architecture, an MDA, ZDA and EDA
will be implemented.
In implementing this structured
cabling design, the datacenter will be seg-
mented based on the logical topology
shown in Figure 5. The segmentation will
be as follows:
1. Collapse the core switching LAN, SAN and aggregation switching in the MDA
2. Segment the access layer into three zones: front-end, application and back-end
Figure 5
DATA CENTER TECHNOLOGY Applying Standards in Data Center Network Design
Figure 7
Blog at www.cablingbusiness.com/wordpress SEPTEMBER 2009 PAGE 13
Applying Standards in Data Center Network Design INSTALLATIONFigure 6
3. Segment the storage into a separate zone
Each zone will use a middle-of-the-
rack interconnect solution for the cabling.
Within each zone, the EDAs will utilize a
top-of-the-rack interconnect. The EDAs
will serve the electronics in each cabinet
and the ZDAs will serve the EDAs. The
ZDAs will homerun back to the MDA,
where they will terminate in a main cross-
connect (MC). This is shown in Figure 7.
CONCLUSIONWhen designing a data center, there
will be many different types of logical
architectures to choose from. These logi-
cal architectures will be deployed over
a hardware and cabling infrastructure.
The TIA-942 Structured Cabling Standard
provides guidance in how to properly
map any logical architecture into a physi-
cal architecture. When applied correctly,
the structured cabling system installed
today will serve the needs of the data
center now and in the future.
With more than 15 years of experience in
communications technology, David Kozischek
currently serves as market manager, Data
Centers for Corning Cable Systems. Kozischek
joined Corning Cable Systems in 1990 and has
held positions in Engineering Services as a senior
field engineer and senior systems engineer;
Strategic Planning and Business Development as
technology manager; and Global Strategic Growth
as a technology discovery manager.