MPLS The Magic Behind the Myths Grenville Armitage
MPLS: The Magic Behind the Myths Grenville Armitage (author) Scott Crosby (presenter)
Problems with IP § No Quality of Service § Necessary for converged network § Realtime voice § Best-effort data § High priority transactions (ATM, control, VC, …) § Performance Scalability § Expensive prefix match for each packet § Traffic Engineering
Problems with IP § Tunneling § Tunnel IP over non-IP intermediate § IP over ATM? IP Network ATM IP Network
Problems with IP § Tunneling § Tunnel IP over non-IP intermediate § Virtual Private Network Abercr. CS IP Network Abercr. EE IP Network Duncan CS IP Network
Problems with IP § Tunneling § Tunnel IP over non-IP intermediate § Virtual Private Network § Traffic Engineering IP Network
What is MPLS? § Virtual circuit layer underneath IP § Virtual circuit = virtual wire = label switched path IP Network (Voice) IP Network (ATM) IP Network (Data) MPLS (Virtual Point-to-Point Circuits) Physical Infrastructure (Point-to-Point Circuits)
What is MPLS? § Offer service above IP § Converged network § Realtime voice § Best-effort data § High priority transactions (ATM, control …) § On the same physical infrastructure § Hop-by-hop Qo. S differentiation
How Does MPLS Work? § Packets are tagged and routed based on tags. § All traffic with the same label treated the same 13 5 IP Routing Layer Payload IP Routing Layer LSR Payload 13 Payload 5 Payload LER 13 Payload 5 Payload
Other Features of MPLS § Tag forwarding distinct from IP forwarding § May make non-shortest paths § Tag routing linked to IP routing IP Forwarding LER (Perform Tagging) LSR Cloud (Forward by tag) IP Forwarding LER (Remove Tag) LSR Cloud (Forward by tag)
MPLS Header § Lightweight § 8 bit TTL § 20 bit label tag § 3 bit Qo. S tag § 1 bit stack § Indicates last LSR tag § Allows heirarchial tagging 13 Payload 13 5 13 Payload 8 13 Payload
Provisioning vs. Signalling § Seconds § Provisioning § Minutes to days § Separate control message protocol § Distribute labels and forwarding info § RSVP § Label Distribution Protocol
Comparing MPLS to IP § IP over MPLS vs IP only § Qos § Performance § Tunneling § VPN § Traffic Engineering
MPLS vs IP: Qo. S § MPLS § Per hop Qo. S § Using labels to prioritize § 20 bit identifier space § IP § Per hop Qo. S § Use IP&TCP header § 104 bit identifier space
MPLS vs IP: Performance § MPLS § Forward on short tags § Not prefix match on address § IP § Routers can forward at gigabit/s
MPLS vs IP: Tunneling § MPLS § Lightweight tunnels § 32 bit header § IP § Heavyweight tunnels § ~160 (? ) bit header
MPLS vs IP: VPN § MPLS § Lightweight § 32 bit header § No security § IP § Heavyweight § ~160 (? ) bit header § No security § (without IPSEC)
MPLS vs IP: Traffic Engin. § MPLS § Arbitrary (non-shortest) paths § Virtual circuits § MPLS routing linked to IP routing § Flexible aggregation § IP § Route announcement manipulation § Path cost manipulation
MPLS vs IP: Future Qo. S § MPLS § Propagate Qo. S between networks § RSVP § IP § Propagate Qo. S between networks § RSVP
Compelling Advantages § Traffic engineering § Management engine § Connectivity § Policy § Constraint based routing § Construct virtual topology § LSP’s § Labels
- Slides: 19