MPLS (Multiprotocol Label Switching)

MPLS

• Simplified forwarding
  • If you look at a layer 2 or 3 header.
  • Take a yellow sticking note and put a number
  • If the router sees that sticky note it nows were to forward it easier.
  • MPLS lives in the Shim
    • This is also called the layer 2.5
  • Makes things fast
  • Makes it scalable
• Label-based
  • Assign different numbers to messages
  • Traffic engineering can occur based on these labels
  • We only need the devices on each end that understand layer 2 or 3.
• Scalable
• Protocol-independent
• Tiered services
• Guaranteed performance

MPLS Components

• Different forwarding tables for each customer.
• It's suppose to be able to carry tons and tons of routes.
• Leveraging multi-prococol BGP, you can learn all those routes from your customers. You provide them across your core.
  • Your Label Switch Routers don't need to hear customer outs.
  • All they are worried about is how do I get these labels from a PE router to a CE router

MPLS Forwarding Engine

RIB / CPU - Routing Information Base (Brain)

• OSPF, ISIS, EIGRP
• LDP
• BGP

FIB / ASIC - Forwarding Information Base (Muscle)

• "Pre-cached answers"
• Typical forwarding decisions
• Performance boosting

LFIB / ASIC - Label Forwarding Information Base

• Dependance upon hardware forwarding

• Labels correspond to remote networks

• As data increases your CPU utilization not necessarily needs to follow, that workload is basically down to the ASICs.

MPLS Routing

• Interior Gateway Protocol (IGP) used in the provider core.
  • Communicating reachability information for how you get around the provider network
• MP-BGP allows us to do this.

• Multi-protocol (MP-BGP) used at provider edges