User's Manual

U-NII Config & User Guide 5.2 Axxcelera Broadband Wireless
4.1 Subnetting
Subnetting within the AB-Access radios is done in hexadecimal format. There for it is
necessary to know the decimal to hex conversions for commonly used subnets. CIDR notation
is also used to define the subnets in all the diagrams, so refer to the chart below for any
questions on subnetting.
Decimal
Subnet
HEX
Subnet
CIDR
0 00 /24
128 80 /25
192 C0 /26
224 E0 /27
240 F0 /28
248 F8 /29
252 FC /30
4.2 Peak Cell Rate - PCR
The Peak Cell Rate is policing not pacing, there for it will discard all cells received over
the limit and not buffer them. This means the cells will be have to be retransmitted via an upper
layer protocol. To calculate the Peak Cell Rate you simply divide the desired bandwidth by the
number of bits in an ATM cell. An ATM cell is 53 bytes consisting of a 5-byte header and a 48-
byte payload. In the following example, the PCR for a 1 Megabit circuit is calculated. PCR
values are rounded to the nearest integer.
1024000 bps/(48 bytes-per-cell*8 bits-per-byte) = 2667
The following table lists PCR values for several, common data rates.
Data Rate PCR
56 kbps 146
128 kbps 333
256 kbps 667
512 kbps 1333
March 10, 2003 Company Confidential Page 14 of 149