Nortel Meridian 1 Description, Installation And Operation page 58

Page 58 of 262 IP Telecommuter Engineering Guidelines
553-3001-119 Standard 2.00 April 2000
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• Obtain total subnet traffic: Number of clients*CCS/client
• Convert to erlangs: total CCS/36
• Find WAN kbps number from bandwidth table
• Bandwidth per subnet: total erlangs*WAN kbps
• Adjust for traffic peaking by *1.3
• Repeat the procedure for each subnet
Adjust WAN bandwidth to account for WAN overhead depending on WAN
technology used:
• ATM (AAL1): subnet bandwidth*1.20 (9 bytes overhead/44 bytes
payload)
• ATM (AAL5): subnet bandwidth*1.13 (6 bytes overhead/47 bytes
payload)
• Frame Relay: subnet bandwidth*1.20 (6 bytes overhead/30 bytes
payload -variable payload up to 4096 bytes)
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Subnet A: 36 clients, average 6 CCS/client.
Total erlangs =36*6/36 =6
Subnet B: 72 clients, average 5 CCS/client.
Total erlangs =72*5/36 =10
Subnet C: 12 clients, average 6 CCS/client.
Total erlangs =12*6/36 =2
WAN Bandwidth to subnet A = 9.3*6=55.8 kbps
WAN Bandwidth to subnet B = 9.3*10 = 93 kbps
WAN Bandwidth to subnet C = 9.3*2 =18.6 kbps
Bandwidth to subnet A with 30% peaking =55.8*1.3 = 72.54 kbps