I am seeing references to Multilayer Switches with Si as in the network symbol below. Multilayer Switch with Si What does the 'with Si' qualifier mean?

2 Answers 2


It means Silicon Switch Processor a high-performance 7000 series router.

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)

  • This is what I was taught.
    – mfinni
    Jul 10, 2014 at 17:13
  • The link you cite refers to Cisco 7000 series routers, but doesn't mention the Nexus 7K series of switches. I would think the use of the Si designation would be redundant on a switch given its logic is encoded in an ASIC already.
    – andand
    Jul 10, 2014 at 17:16
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    Nexus is a line of product of it's own. It has nothing to do with the Cisco 7000 series, a product that's End-of-Sale and End-of-Life. I added a link to the product description. I also changed switch to router...my bad.
    – Alex
    Jul 10, 2014 at 17:21
  • Okay, but the question relates to switches, not routers.
    – andand
    Jul 10, 2014 at 17:23
  • See the edit to answer your question regarding switches vs routers.
    – Alex
    Jul 10, 2014 at 17:38

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.

  • 1
    and a detailed comparison of the two here
    – HBruijn
    Jul 10, 2014 at 17:02
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    That would be SI not Si (like the periodic table sign for silicon, see the other answer).
    – faker
    Jul 10, 2014 at 17:05
  • I'm not sure you're correct in this context. Do you have any links to documentation that indicates this is what is meant in the graphic icon shown? Can you find an example of an icon with an Ei in the middle?
    – mfinni
    Jul 10, 2014 at 17:13
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    No, the Catalyst 2950 did not exist in the 1990s, and that is when the Si icon in question was first marketed. Perhaps you got the idea that it's "Standard Image" from Leo Laohoo's answer; while Leo is usually spot-on, in this case he's quite full of poo. The answer from acampbell on the same page is correct (and provides proof). Jul 11, 2014 at 6:37

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