Connection setup 3rd important function in some network architectures: ATM,frame relay,X.25 before datagrams flow,two end hosts and intervening routers establish virtual connection o routers get involved network vs transport layer connection service: o network:between two hosts(may also involve inervening routers in case of VCs) o transport:between two processes Network Layer 4-7 Network Layer 4-7 Connection setup  3 rd important function in some network architectures:  ATM, frame relay, X.25  before datagrams flow, two end hosts and intervening routers establish virtual connection  routers get involved  network vs transport layer connection service:  network: between two hosts (may also involve inervening routers in case of VCs)  transport: between two processes