To test raw speed with iPerf you should have it in udp mode and run a bi-directional test.
Two other things spring to mind though;
1) Will an 1841 handle 50mbit? check the routerperformance PDF.
2) I recall seeing in a tech note somewhere before that the bandwith on a tunnel interface is limited to 8 or maybe 10mbit depending on the feature set of the IOS. I can't find that note now, but I'm sure a search might get it.
EDIT: Although, as Edison notes, If you get those speeds between the same two hosts with concurrent sessions then it is likely to be a host problem.
This is actually a pretty cool feature, i didn't even know it existed until I was looking for a solution to advertise a subnet (prefix in BGP talk), only if a certain condition existed. This is exactly what conditional advertisements does
j ai une question j ai achete un routeur cisco 887VA-k9 , je le configuré avec la configuration ci- dessous
si je le lier avec mon pc portable sur l un de ses ports directement ça marche toute est bien ( la connexion internet + m...
Attached policy provides CLI access to the Cisco 4G router over text messaging. Two files are in the attached .tar file:
2. PDF with instructions on how to load and use the .tcl file.