Outline Exam discussion Layering review(bridges, routers, etc. 》 Exam section c Circuit switching refresher Virtual circuits- general Why virtual circuits? > How virtual circuits?- tag switching! Two modern implementations >)ATM-teleco-style virtual circuits >)MPLS-IP-style virtual circuits 22 Outline Exam discussion Layering review (bridges, routers, etc.) » Exam section C. Circuit switching refresher Virtual Circuits - general » Why virtual circuits? » How virtual circuits? -- tag switching! Two modern implementations » ATM - teleco-style virtual circuits » MPLS - IP-style virtual circuits