time of his arrival, so that the only thing that the Rider had to do was strap the mail to the horse, mount the horse, and continue on his journey. (The mailbags were made in a manner so that they could be removed from one animal and placed on another in a minimal amount of time). At home stations, Riders were switched in a speedy fashion, as well (Dicerto 16).Another aspect of Flow Control performed by the Pony Express was the method of keeping track of the times at which the Riders arrived at each station. A time card would travel with the Rider, and the station keeper at each station would indicate the time at which the Rider arrived at that station. This insured that the Riders were transporting the letters at optimum speed. Only the station keepers had access to this time card because of the manner in which it was stored (as will be discussed in the section dealing with the Physical Layer). This limited access to the time card ensured proper in-route protection of the message it contained (Dicerto 24). The letters were locked up in a manner so that they could only be accessed at military forts (as will be further detailed in the Physical Layer section); this is a further example of protection performed by the Pony Express (Oslin). Sacramento was the end of the Pony Express route. Letters that were to continue on to San Francisco were loaded onto a steamboat for this final leg of the journey (Dicerto 27).The next layer within the OSI Model is entitled the Data Link Layer. It is the job of the Data Link layer to make sure that the contents of the message do not become corrupted while the message is transported from one intermediate destination, along the route, to the next (Stamper 29).In the Pony Express, Data Link Layer tasks were the responsibility of the Rider. The Rider brought the letters from one station to the next, traveling 75 miles per day. During this letter transport, the rider made sure that the letters were not lost or...
