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RFC 4191 Router Preferences and More-Specific Routes

RFC 4191 Router Preferences and More-Specific Routes. Speaker: Ching-Chen Chang Date: 20070612. Outline. Introduction Preference Value The Format of message Conceptual Model of Host Example Reference. Introduction.

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RFC 4191 Router Preferences and More-Specific Routes

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  1. RFC 4191 Router Preferences and More-Specific Routes Speaker: Ching-Chen Chang Date: 20070612

  2. Outline • Introduction • Preference Value • The Format of message • Conceptual Model of Host • Example • Reference

  3. Introduction • An optional extension to Neighbor Discovery Router Advertisement messages for communicating default router preferences and more-specific routes from routers to hosts. • using Neighbor Discovery • Router Advertisement are an existing standard and stable protocol. • Shielding the host from having to participate in more router-to-router interactons. • It carries route lifetimes.

  4. Preference Value

  5. The Format of message(1/3) 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 ++++++++++++++++++++++++++++++++++++++++++++++ | Type | Code | Checksum | ++++++++++++++++++++++++++++++++++++++++++++++ | Cur Hop Limit |M|O| Reserved | Router Lifetime | ++++++++++++++++++++++++++++++++++++++++++++++ | Reachable Time | ++++++++++++++++++++++++++++++++++++++++++++++ | Retrans Timer | ++++++++++++++++++++++++++++++++++++++++++++++ | Options | ++++++++++++++++++++++++++++++++++++++++++++++

  6. The Format of message(2/3) 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 ++++++++++++++++++++++++++++++++++++++++++++++ | Type | Code | Checksum | ++++++++++++++++++++++++++++++++++++++++++++++ | Cur Hop Limit |M|O|H| Prf |Resvd | Router Lifetime | ++++++++++++++++++++++++++++++++++++++++++++++ | Reachable Time | ++++++++++++++++++++++++++++++++++++++++++++++ | Retrans Timer | ++++++++++++++++++++++++++++++++++++++++++++++ | Options | ++++++++++++++++++++++++++++++++++++++++++++++ Prf => Default Router Preference

  7. The Format of message(3/3) 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 ++++++++++++++++++++++++++++++++++++++++++++++ | Type | Length | Prefix Length |Resvd|Prf|Resvd| ++++++++++++++++++++++++++++++++++++++++++++++ | Router Lifetime | ++++++++++++++++++++++++++++++++++++++++++++++ | Prefix (Variable Length) | . . ++++++++++++++++++++++++++++++++++++++++++++++

  8. Conceptual Model of Host • Type A: Neighbor Discovery. • Type B: Hosts uses a Default Router List augmented with preference values, but ignore all Route Information Options. • Type C: Hosts use a Routing Table instead of a Default Router List.

  9. Example ::/0 -> router W with a Medium prefrence 2002::/16 -> router X with a Medium preference 2001:db8::/32 -> router Y with a High preference 2001:db8::/32 -> router Z with a Low preference

  10. Reference RFC 4191 Default Router Preferences and More-Specific Routes • http://www.faqs.org/rfcs/rfc4191.html RFC 3775 Mobility Support in IPv6 • http://www.faqs.org/rfcs/rfc3775.html RFC 2461 Neighbor Discovery for IP Version 6 • http://www.faqs.org/rfcs/rfc2461.html

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