The Enhanced Interior Gateway Routing Protocol (EIGRP) is an advanced  
distance-vector routing protocol, with optimizations to minimize both  
the routing instability incurred after topology changes, as well as  
the use of bandwidth and processing power in the router. We show here  
an executable specification using the rewriting logic based language  
Maude, that allows us to connect several Maude instances, each one  
running the protocol and on top of which concrete applications can be  
executed. We also simulate the protocol by using Real-Time Maude, that  
allows us to formally analyze it in several ways.