MSFC and FlexWAN Architectural Overview 339
The FlexWAN module binds to the active or designated MSFC within the 6500. As stated
in the introduction, the FlexWAN extends the Catalyst 6500’s reachability to the MAN and
WAN. The FlexWAN is a single-slot module that can be integrated into the Catalyst 6500.
The physical appearance of the FlexWAN module can be compared to a Versatile Interface
Processor (VIP) for a 7500. Similar to the VIP, the FlexWAN has two bays, which accom-
modate two modular WAN port adapters. From the MSFC, the FlexWAN port adapters are
configured identically to the way Cisco 7200 or 7500 port adapters are configured. The
FlexWAN contains two VIPs capable of supporting one port adapter for each VIP. The
FlexWAN port adapters are configurable strictly from the MSFC and not recognized by the
switch in Hybrid mode. If running the Cisco Native IOS, the FlexWAN module interfaces
are configured from the command line similar to any other available interface. Table 9-3 depicts
the 7200/7500 WAN port adapters supported by the FlexWAN.
Unlike the VIP, which only incorporates a single processor and memory to control both
bays, the FlexWAN module is comprised of two VIPs. Therefore, the FlexWAN module
services the two installed port adapters with a dedicated processor and memory for each
bay. Each processor performs the encapsulation and QoS functions independently for its
assigned slot. Also the MSFC communicates with each processor on the FlexWAN
independently through the Ethernet out-of-band channel (EOBC). However, only system
control information is exchanged via the EOBC. Routing and forwarding decisions are still
maintained by the MSFC and central PFC. As a result, the FlexWAN uses the central data
bus (D-bus) and results bus (R-bus) for forwarding and receiving data packets. This even
applies for packets being forwarded out a different subinterface on the same port adapter.
The D-bus, R-bus, and EOBC are introduced in Chapter 8.
For more detailed information regarding the architecture of the Catalyst 6500, consult the
following technical document at Cisco.com:
“Catalyst 6000 and 6500 Series Architecture”
Hardware and Software Requirements
As described in Chapter 8, the administrator has two software options available to support
operations on the Catalyst 6500. The first option requires the administrator to load two
separate software versions. One version supports the supervisor module, and the other
version supports the MSFC. This configuration is referred to as Hybrid mode. The alter-
native arrangement requires only one version of software to be positioned on the platform.
This one version sustains both the supervisor and the MSFC. This version of software is
referred to as Cisco Native IOS.
For additional information on naming conventions and differentiating the various software
versions for the Catalyst 6500, refer to the section titled “Identifying the Catalyst Software”
in Chapter 8.