Using direct links to form network among a bunch nodes.
User router/gateway to connect clouds of network
We can form networks recursively by interconnect networks
Cost-effective resource sharing
Don’t want idle links. Don’t want to starve users. Don’t want switches to drop packages.
Support for common services
Need to find common patterns across different applications
Request and reply
FTP uses this pattern
Only 1 copy and guarentee transfer
video and conferences
Danger of too few channel abstractions
If you have only a hammer, everything looks like a nail.