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Hands-On Design Process
for Voice Networks
1. Model Voice Grade (VG), 56-Kbps &
T-1 Leased lines
2. Model 1, 2 & 3 Optimally-Located
SWs
3. Model leased lines and virtual lines
by using ECC values of 13.33 and 1.00.
4. The above tasks are executed for an hypothetical
enterprise (let us name it Hi-Tech) that consists of 17
sites with headquarters in Las Colinas, Texas. These
17 sites are served by two legacy voice and data
networks (separate and distinct).
Existing network employs leased voice grade (VG)
lines. Each VG line can handle either 1 conversation
or 9600 bps data rate.
The specifications for the VGLs (and for 56 Kbps,
T-1 and T-3 lines) are defined in the enclosed NLT
input file.
5. The existing networks employ a voice switch and a
data switch (FE + Host), both located at Las Colinas.
6. In order to understand the design of VoIP networks,
one must first understand the design of legacy voice
and data networks.
7. The design data for existing networks is provided in
input files, FILES, VHD17, NLT and SDF.
8. We will describe the design process and design
parameters first for the voice networks and then later
for the data networks. Later we will first design an
integrated V/D network using CS technology (using
TDM technique) and later we will design a VoIP using
IP/PS technologies.
VOICE NETWORKS:
The Overall Design Process
• Prepare a VHD file using the CPE data
• Prepare a NLT file for useful link types
• Select the valid tariffs in a TARIFF file
• Prepare a valid LINK file if required
• Use the “Find COGs”capability for
choosing # of SW locations for creating
a valid SWF input file.
• Adjust the SDF design parameters
Voice-Related Design Parameters
• ALT
(=AL Type Per the LINK file)
• TKLT=TK Link Type for voice/data networks
• Bal, Btk (Blocking allowed on ALs & TKs)
• BBTF (Backbone trunking factor influencing
the amount of inter-nodal traffic flowing on
trunks for the case nodal TCA BHR traffic
intensities are used for modeling a network.)
• ECC: Econom. Cost of a 5-Min Call
• Factors ALMF and TKMF as defined in NLT
SDF Design Parameters(Contd.)
• By choosing Flk=0, one obtains a
voice network with all ALs with a
single type determined by ALT
• By choosing Flk=1, one obtains a
voice network with a mix of AL
types as determined by the values
of the LINK file named in FILES.
• TGF must = 1 for all runs.
Voice Network Design Process
1. Open/View the input file “Files” and
enter VHD17, LINK17, MAPusa,
TARIFF, SDF, NAME17, LATA17 and
SWF in the proper cells and UPDATE.
2. Open/View the input file “SDF” and
update values of ALT=1, TKLT=1,
Bal=0.1, Btk= 0.1, ECC=13.33 (leased
lines only), ALMF=1 and TKMF=1 for
leased VG lines.
3. Run FindCOG and compute the opt.
location of 1 SW at 1, 2 SWs at 1, 11
and 3 SWs at 1, 11, 2. (Explain why?)
4. Use SWF with 1 SW at 1, 2 SWs at 1
and 11, 3 SWs at 1, 11 and 2 to create
three VoiceNets.
5. Repeat Steps#2, 4 for ALT=2,
TKLT=2 and ECC=13.33 (leased line
only) to crreate 3 more VoiceNets
6. Repeat Steps#2 and 4 for ALT=3,
TKLT=3 and ECC=13.33 (for leased lines
only) to create 3 more VoiceNets.
7. Now we have 9 VoiceNet topologies.
Repeate the Steps#2, 4, 5, 6 with ECC=1
(I.e. modeling $1.0 for a 5-Min call on the
virtual public network. We now have a
total of 18 VoiceNet topologies.
8. Tabulate results to find the Optimum
VoiceNet topology. Add Remarks.
9. For the optimum VoiceNet, tabulate
the total transmission costs versus
Bal/Btk. Make some observations about
the optimum network.
10. Considering the 18 VoiceNets, find
the ones which are hybrid networks (i.e.
using a mixture of leased lines and
virtual lines). Hint: Study the output
files and find sites served by either
leased lines or virtual facilities.
VoiceNet Assignments
1. Create a MSWord document with
tabulation of 18 VoiceNets with your own
remarks.
2. Include a DBF Output file for the
Optimum VoiceNet.
3. Include the tabulation of Total Monthly
Costs for Optimum net Versus Bal/Btk with
observations about the optimum VoiceNet
VoiceNet Assignments
(Contd.)
4. Include a TKF for the Optimum VoiceNet
and check values in original traffic and
modified-traffic matrices.