I am seeing references to Multilayer Switches with Si as in the network symbol below. What does the 'with Si' qualifier mean?
According to the answer from dtlokee in this Cisco forum, it does stand for SSP.
They use the Si for the "silicon switching", I guess it's a bit dated but that is how they would represent a switch doing L3 switching in hardware. Now I think it goes without saying that multilayer switching is done in hardware. They also used a switch icon with an extra bit on the bottom that had 4 rectangles with lines between them to represent a L3 switch with the MFFC installed (going back to the 5000/5500 here)
SI stands for the Standard Image. There is also an EI version which is the Enhanced Image.
The Cisco Catalyst® 2950 Series switches include two software image versions that support different degrees of functionality—the Standard Image (SI) and the Enhanced Image (EI) Software. The version of software depends solely on the model of switch selected, with no upgrade capabilities.
The SI version is embedded in Cisco Catalyst 2950-12, 2950-24, and 2950SX-24 switches, and supports basic Cisco IOS® functionality, Fast Ethernet connectivity, and cluster management.
The EI version supports all that and more. The EI version of software is embedded in Cisco Catalyst 2950T-24, 2950C-24, and 2950G-12, 2950G-24, 2950G-48 switches, and supports advanced intelligent services, gigabit connectivity, and a richer set of features. These include Cisco Spanning-Tree Protocol enhancements for high availability, access control parameters (ACPs) for enhanced security, and Differentiated Services Code Point (DCSP) and rate limiting for advanced quality of service.