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
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- 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
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Dependance upon hardware forwarding
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Labels correspond to remote networks
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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.
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- Multi-protocol (MP-BGP) used at provider edges