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Metarouting (SIGCOMM 2005) T. G. Griffin and J. L. Sobrinho

Metarouting (SIGCOMM 2005) T. G. Griffin and J. L. Sobrinho. Background: BGP is used as IGP? Why? Routing protocols are hard to develop and deploy . What is in this paper: A new approach to define and deploy new routing protocols by composing protocols from existing protocol elements.

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Metarouting (SIGCOMM 2005) T. G. Griffin and J. L. Sobrinho

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  1. Metarouting(SIGCOMM 2005)T. G. Griffin and J. L. Sobrinho

  2. Background: • BGP is used as IGP? Why? • Routing protocols are hard to develop and deploy. • What is in this paper: • A new approach to define and deploy new routing protocols by composing protocols from existing protocol elements. • A clear separation between protocol mechanisms (how information is exchanged) and routing policies (how routes are described and compared). • Use routing algebras (route preference is rigorously captured in algebraic structures) to describe the policy component. • Use a language, RAML, to define more complex algebras from simpler ones. • RAML allows the correctness property to be derived automatically.

  3. Routing protocols • Mechanisms • How to exchange route information • Route selection algorithm • Rely on the policy component to determine route preferences • Policy: • Information describing the characteristics of routes • The method to compare characteristics to determine route preference. • The method to apply policies to routes • This paper focuses on using routing algebra to describe policy.

  4. Routing algebras: • Signatures describe the characteristics of a route • Signatures can be the path, path length, the path weight, etc. • The route preference is determined only based on the route signatures • Link weight is generalized as a policy label.

  5. Routing algebra:

  6. A routing protocol computes routes that have the form: • Different routing protocols correspond to different operator (+), and thus, different algebras.

  7. Convergence guarantees: • The routing protocol must eventually determine the stable forwarding tables that implement loop-free paths between every pair of nodes • In routing algebra, algebraic properties are identified for routing algebras: • E,g for vectoring algorithms:strict monotonicity (SM) guarantees correctness:

  8. Convergence guarantees: • For link state algorithm: • Associativity of + • Isotonic: • Left-SM and right SM

  9. Base Algebras:

  10. A Routing Algebra Metalanguage: • Define a protocol RP as RP = (A, M, LM) • Routing Algebra Meta-Language (RAML) defines A – make it easy by automatically derived monotonicity conditions.

  11. Lexical Product

  12. Scope Product:

  13. Disjunction, • An operation that allows the use of either A, or B, or both

  14. Monptpnicity Preservation:

  15. Routing algebra for a RIP-like protocol that supports complex policy routing:

  16. Routing algebra for the RIP-like protocol for a three-level network(metropolitan area networks (MAN), regional area networks (RAN), and global networks (GN):

  17. Modeling the policy component of BGP:

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