Virtual chassis is very similar to a distributing computing concept called a single system
image (SSI), which is a cluster of devices that appears to be a single
device. However, simply appearing to be a single device isn’t good enough;
all of the fault tolerance features that are available in a physical
chassis need to be present in the virtual chassis as well. This creates a
unique engineering challenge of constructing a virtual chassis that looks,
feels, and behaves like a true chassis, as shown in Figure 6-1. The two routers
joined together by a virtual chassis port (VCP) to form a virtual
Figure 6-1. Illustration of Virtual Chassis.
Once the two routers have been configured to participate in virtual
chassis, the virtual chassis will now act as a single router. For example,
when you log in to the router and execute commands such as
show chassis hardware or
show interfaces terse, you will see the hardware
inventory and interface list of both routers.
There are several features that contribute to the high availability in a typical chassis:
Redundant power supplies
Dual routing engines
Graceful routing engine switchover
Multiple line cards
Each component is fully redundant so that there isn’t a single point of failure within a single chassis. Virtual chassis takes the same high-availability features that are found ...