As I am architecting network designs there are many protocols and technologies to consider, a few of them being First Hop Redundancy Protocols (FHRP), Virtual Switching System (VSS), and Virtual Port Channel (vPC), Routing Protocols like OSPF or EIGRP, and the necessary evil Spanning-Tree (STP).  Each of these protocols value a larger number vs. lower number differently from a priority perspective.  Some of these protocols use the lower value as a higher priority and others use a higher number as the higher priority. GCSIT Mail Security 

A perfect example of this is how STP treats its values versus how HSRP does.  With STP you can force a bridge to become the elected root by changing the bridge priority to a number that is lower than all other bridges.  On the other hand when you are configuring HSRP and want to control what switch becomes the HSRP active member you assign it a higher number than all other members participating in HSRP. 

The table below shows some of the common protocols and technologies that I tend to run into when doing network designs.  It is a good tool to reference to ensure I am using the proper numbers to net the desired effect. 

prioity chart 0415