High Availability Network Fundamentals

Cisco uBR 7246 Availability Calculations

The Cisco uBR 7246 cable head end router is the head end that a uBR 924 would connect to via a cable company's “cable plant.” For our purposes, we will consider the cable plant to be a simple coax cable between the uBR 7246 and the uBR 924. However, this is definitely not true in the real world, and in Chapter 9 you will see that we account for downtime (and explain additional detail) of the cable plant in our network calculations.

Figure 6-4 shows a diagram of the uBR 7246 router. On the front side of the router, the key features are the four slots on the lower half that allow insertion of up to four adapter cards for cable ports. The recessed upper half includes three slots for the insertion of CPU cards ...