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This chapter provides an overview of the Cisco MGX 8850 Route Processor Module (RPM) and its relationship to the MGX 8850 switch.
This chapter contains the following sections:
The RPM is a high-performance router module based on the Cisco 7200 NPE-150 router, modified to fit into a 32-slot, full-height MGX 8850 switch. The RPM substantially enhances the MGX 8850 product. The Cisco 7200 NPE-150 router engine is capable of processing up to 140k pps. It is a double-height service module that can be placed in any of the MGX 8850 service module slots
(see Figure 1-1).
The RPM provides integrated IP in an ATM platform, enabling services such as integrated Point-to-Point (PPP), Frame Relay termination, and IP virtual private networks (VPNs) using MPLS technology. It provides Cisco IOS(tm)-based multiprotocol routing over ATM, Frame Relay and ATM Interface Layer 3 Termination, Local Server Interconnect over High Speed LANs, Access Concentration, and switching between Ethernet LANs and the WAN facilities of the MGX 8850.
The RPM includes interprocessor communication to the main processor switch control module (called the PXM) in the MGX 8850 for management, including configuration, mode supervision, (e.g. redundancy/load sharing control) and software and configuration file management.
The RPM module installs in a 32-slot full-height MGX 8850 chassis and connects to the PXM (and other service modules) via the midplane.
The RPM receives power from the midplane and communicates over the midplane with the PXM using IPC over ATM. As a Cisco 7200-based router, the RPM runs Cisco IOS software.
The RPM, when installed in the MGX 8850 chassis, functions like a Cisco 7200 NPE-150 router installed in the MGX 8850 switch. The MGX 8850 is impacted by the traffic load coming from the MGX 8850 RPM. On a network topology map, the combined system looks like a Cisco 7200 NPE-150 router connected to a MGX 8850.
All RPM trunk traffic is placed over its integrated ATM interface to the MGX 8850 cellbus (the ATM port is connected to the cellbus), or to the PXM uplink to the PXM, which routes it to the appropriate service module or RPM. Both the RPM and the PXM are configured manually to create the appropriate connections before any user data can flow through the PXM.
The RPM has an integrated ATM interface---a permanently attached ATM port adaptor based on the Cisco ATM deluxe module---and can support up to two optional port adapters to provide LAN connectivity (see Figure 1-3). The two extra port adapters are based on existing port adaptors (4E, Fast ethernet and FDDI) that have been re-packaged to fit the MGX 8850 chassis.
The MGX 8850 RPM installs into one slot in the MGX 8850 chassis and connects to the MGX 8850 midplane (see Figure 1-1). When the RPM is installed (in the front of the MGX 8850 chassis), its port adapters must also be connected to the midplane (from the rear of the MGX 8850 chassis) and their ports cabled to network devices (refer to Figure 1-2 to see installation. Refer to Chapter 4, "Cabling Cisco MGX 8850 RPM Port Adapters" for cable and connection details).
The RPM uses an NPE-150 Cisco 7200 router engine, an integrated ATM interface, and the cellbus ASIC to interface with the MGX 8850 cellbus controllers.
The MGX 8850 shelf can be completely populated with a total of 12 RPM blades. This allows you to use multiple RPMs to achieve load sharing. Load sharing is achieved by manually distributing connections across multiple embedded RPM router blades.
The RPM fits into the MGX 8850 midplane architecture with the front card providing Cisco IOS router services, and the port adapters providing physical network connectivity. The RPM front card also provides ATM connectivity to MGX 8850 cellbuses at full duplex OC-3.
The RPM port adapters are connected to the front card by a dual PCI bus (refer to Figure 1-3). The RPM port adapters are derived from existing Cisco 7200 port adapters. Each RPM card can be equipped with up to two single-height port adapters. Initially three single-height port adapter types are supported. They are:
The RPM supports the following router protocols:
RPM port adapters do not contain "Burned-In" (BIA) MAC addresses for their ports. Instead, MAC addresses for the RPM are stored within NVRAM located on the MGX 8850 midplane.
After power-on, the PXM retrieves MAC addresses from NVRAM and sends them to each RPM card within the MGX 8850 chassis. The RPMs then assign unique MAC address sets to their port adapter interfaces.
Table 1-1 summarizes the key attributes of the RPM card.
| Front card | RPM |
| Card dimensions | 15.65" x 15.83" (double-height) |
| Processor | 150 MHz R4700 RISC |
| IP router throughput | 140,000 packets per second |
| Cellbus interface speed | OC-3 |
| Memory | Up to 128 Mbytes DRAM, up to 20 Mbytes Flash |
| Console port | Configuration Port; asynch interface speed based on config-register up to 19,200 baud |
| Auxiliary port | Maintenance Port; asynch interface speed configurable up to 11,200 baud |
| Port adaptors | 4-port Ethernet (10BaseT) 1-port Fast Ethernet (UTP, MMF) 1-port FDDI (full duplex, half duplex, SMF, MMF) |
The MGX 8850 cellbus (actually a dual PCI bus) in the MGX 8850 midplane communicates between the RPM, service modules (slaves) and the PXM (master) (refer to Figure 1-3). Each cellbus is connected to a set of PXM cards. Only one cellbus may be active at a time.
Communication from master to slaves consists of a broadcast to all slaves. The first byte of the cell header contains addressing information. Each slave will monitor data traffic and `pick up' cells which are destined to their slot. There is also a multicast bit which allows all slaves to receive a cell simultaneously.
Communication from the slaves to the master is more complicated. Since many slaves might want to transmit simultaneously, arbitration among slaves is required. At the start of a given cell period, the master will poll all slaves to see if they have anything to send. By the end of the current cell, the master will grant, or allow, one of the slaves to transmit. Polling and data transmission occur simultaneously.
The interconnect to the MGX 8850 cellbus and the RPM port adapters is done through two sets of connectors placed at the rear of the RPM PCB (see Figure 1-3). The two connectors each have
360 pins, for a total of 720 pins. The top and bottom connector are identical, mechanically. They are each comprised of three sections---a top, a middle, and a bottom section.
The LEDs indicate the current operating condition of the RPM (see Figure 1-4). You can observe the LEDs, note the fault condition the RPM is encountering, and contact your system administrator or, if necessary, customer service. For a table showing how to interpret RPM front panel LED activity, refer to Appendix A, "Maintaining the Cisco MGX 8850 RPM," in the section "Reading Front Panel LEDs."
The RPM is supported in Cisco IOS Release 12.0(5)T or later.
For more information about RPM software configuration, refer to the Cisco IOS configuration and command reference publications.
There are two versions of the RPM card. The RPM-A is equipped with 4 Mbyte SIMMs for flash memory, and can be equipped with up to 16 Mbytes of flash. The RPM-B is equipped with 16 Mbyte SIMMs. Both versions can support up to 20Mbytes of flash memory.
The version is labeled on the front of the card. You can also execute the show controller command on the switch interface and note the ATMIZER II revision number. The RPM-A will show 2, while the RPM-B will show 3.
Posted: Tue Oct 19 08:41:18 PDT 1999
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