Cisco Systems RJ-45-to-AUX manual Crescendo Processors, Crescendo Logic Units

This ASIC operates in either master or slave mode. In master mode, the ASIC allows ports access to the bus based on a priority level of normal, high, or critical. In slave mode, each port must post a request to each SAMBA ASIC, negotiate local port decisions, and arbitrate requests with the Supervisor Engine’s SAMBA ASIC.

The Crescendo Processors

Although we have ASICs to do some of the hard work of the processors, processors still must be involved to handle the more dynamic administrative items. They carry the intelligence behind the frame−switching process. Inside the Crescendo Interface Internetwork Operating System (IOS) switches, the processors connect to a bus; the bus in turn connects to other ASICs and processors inside the switch. In the following sections, I will examine the processors listed here and their assigned functions. You will find these processors in the Crescendo Interface Catalyst switches:

∙Line Module Communication Processor (LCP)

∙Master Communication Processor (MCP)

∙Network Management Processor (NMP)

LCP

The Line Module Communication Processor (LCP) can be found on each line module in the switch. This ASIC’s responsibility is to provide communications for access to the Master Communication Processor (MCP) located on the Supervisor Engine.

The LCP automatically boots from read−only memory (ROM) and is an 8051 processor. Immediately upon boot up, the ASIC forwards an information package called a Resetack to the MCP. Resetack includes information regarding the switch’s boot diagnostics and module information. This information is then forwarded from the MCP to the Network Management Processor (NMP).

MCP

The Master Communication Processor (MCP), which is sometimes called the Management Control Processor, uses a serial management bus to communicate between the NMP on the Supervisor Engine module and the LCP on the individual line cards located in the switch. The MCP also has a secondary job: to test and check the configuration of the local ports, control of local ports, downloading of runtime code, and performing continuous port diagnostics. This ASIC handles the diagnostics and obtains the usage statistics of the on−board memory, ASICs, Local Target Logic (LTL), and Color Blocking Logic (CBL).

NMP

The Network Management Processor (NMP) is used to control the system hardware, configuration, switch management, the Spanning−Tree Protocol (STP) (discussed in Chapter 10), and diagnostic functions.

Crescendo Logic Units

Logic units provide logic−based forwarding by VLAN, MAC address, or port assignment. The Catalyst Crescendo Interface switches contain the following logic units:

∙Arbiter (ARB)

∙Local Target Logic (LTL)

∙Color Blocking Logic (CBL)

∙Remote Network Monitoring (RMN)

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