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This soft copy for use by IBM employees only.
4.2 Some Common Elements among the 8285 Modules
The following sections describe some of the common elements shared by the
8285 modules.
4.2.1 Maximum Capacity
All 8285 modules have a backplane capacity of 212 Mbps. In order to provide
guaranteed service, the maximum configurable reserved bandwidth is 185 Mbps
(85% of 212 Mbps). The non-reserved traffic will use whatever bandwidth is
available, including bandwidth that is reserved but not being used.
4.2.2 Variable VPC/VCC Value Ranges
With the latest release of 8285 code (Release 1.4), the 8285 modules now support
variable VPC/VCC range values. That is to say, they allow you to manage your
network more precisely by allocating varying numbers of bits to the VPC and
VCC portions of the header on a port-by-port basis.
Note
The VPC/VCC range
must
be the same on both ends of an SSI or NNI link.
With one exception, noted below, all of the modules allocate 14 bits to the
VPC/VCC portion of the header, which you can allocate in one of the following
ways:
•
Mode 0/14 (all 14 bits assigned to VCC):
− VPC=0
− VCC range is 0-16383
•
Mode 4/10 (4 bits for VPC, 10 bits for VCC):
− VPC range is 0-15
− VCC range is 0-1023
•
Mode 6/8 (6 bits for VPC, 8 bits for VCC):
− VPC range is 0-63
− VCC range is 0-255
The exception to the above is the newest module, the ATM 12-Port 25 Mbps UTP
Concentrator Module, which allocates only 12 bits to the VPC/VCC portion of the
header, and which allows the following modes:
•
Mode 0/12 (all 12 bits assigned to VCC):
− VPC=0
− VCC range is 0-4095
•
Mode 2/10 (2 bits for VPC, 10 bits for VCC):
− VPC range is 0-3
− VCC range is 0-1023
•
Mode 4/8 (4 bits for VPC, 8 bits for VCC):
− VPC range is 0-15
− VCC range is 0-255
36 ATM Workgroup Solutions: Implementing the 8285 ATM Switch