ATM came about as a technology that provided a combination of the best parts of circuit-switched networks and packet-switched networks.
SDH/SONET is synchronous because it associates a fixed relationship between timeslots and the data it carries. For instance, in a channelised E1 with timeslots 1-20 assigned to circuit1 and timeslots 21-31 assigned to circuit2, there will always be a fixed relationship between timeslots and circuits - timeslots 1-20 will always carry circuit 1 traffic and timeslots 21-31 will always carry circuit 2 traffic.
The asynchronous in ATM does not refer to physical layer synchronisation. It refers to the fact that there is no relationship in timing between ATM cells and the data it carries. For a simplistic case, consider a link with a cell rate of 3 cells/sec. In one second, cell1 can carry data for PVC1, cell2 can carry data for PVC2 and cell3 can carry data for PVC3. In the next second cells 1 to 3 can all carry data for PVC2. That's what makes it asynchronous, that there is no correspondence between cell number and the PVC.
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.