Question

How does constraint based routing enable traffic engineering?

Answer 1

Constraint-based routing is a kind QoS (Quality of Service) routing technique that has become vital with the event of MPLS (Multiprotocol Label Switching). However, RFC 2702 (Requirements for Traffic Engineering Over MPLS, Sep 1999) notes that QoS routing is absolutely a set of a lot of broadly speaking outlined constraint-based routing approach.

MPLS may be a protocol for carrier-based core networks that run over MPLS-enabled information science routers and ATM switches. Such devices area unit is known as MPLS LSRs (label switch routers). associate degree MPLS network permits the definition of specific ways, that area unit predefined routes through networks as against routes that area unit elite at every router on a hop-by-hop basis. Routing protocols like OSPF and BGP confirm these specific routes before, and so build tables in every router that outline the routes. Packets carry labels to point that specific route they must be taking. Thus, labeled packets follow LSPs (label switched paths).

The preceding procedure of victimization customary routing protocols to outline specific ways is absolutely the default procedure, and it will come about while not operator intervention. additionally, MPLS is versatile enough to outline ways supported varied constraints like out there information measure, the priority setting of packets, the whims of associate degree operator, or the directives of a policy-based server. Thus, MPLS conjointly supports cosmic radiation (constraint-based routing).

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