IBM SG24-4817-00 manual Some Common Elements among the 8285 Modules, Maximum Capacity

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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):

−V P C = 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):

−V P C = 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

36ATM Workgroup Solutions: Implementing the 8285 ATM Switch