RFC 4191 Router Preferences and MoreSpecific Routes Speaker

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

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

Outline n n n Introduction Preference Value The Format of message Conceptual Model of

Outline n n n Introduction Preference Value The Format of message Conceptual Model of Host Example Reference

Introduction n n An optional extension to Neighbor Discovery Router Advertisement messages for communicating

Introduction n n 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 q q q Router Advertisement are an existing standard and stable protocol. Shielding the host from having to participate in more routerto-router interactons. It carries route lifetimes.

Preference Value 01 High 00 Medium 11 Low 10 Reserved

Preference Value 01 High 00 Medium 11 Low 10 Reserved

The Format of message(1/3) 0 1 2 3 0123456789012345678901 +++++++++++++++++++++++ | Type | Code

The Format of message(1/3) 0 1 2 3 0123456789012345678901 +++++++++++++++++++++++ | Type | Code | Checksum | +++++++++++++++++++++++ | Cur Hop Limit |M|O| Reserved | Router Lifetime | +++++++++++++++++++++++ | Reachable Time | +++++++++++++++++++++++ | Retrans Timer | +++++++++++++++++++++++ | Options | +++++++++++++++++++++++

The Format of message(2/3) 0 1 2 3 0123456789012345678901 +++++++++++++++++++++++ | Type | Code

The Format of message(2/3) 0 1 2 3 0123456789012345678901 +++++++++++++++++++++++ | Type | Code | Checksum | +++++++++++++++++++++++ | Cur Hop Limit |M|O|H| Prf |Resvd | Router Lifetime | +++++++++++++++++++++++ | Reachable Time | +++++++++++++++++++++++ | Retrans Timer | +++++++++++++++++++++++ | Options | +++++++++++++++++++++++ Prf => Default Router Preference

The Format of message(3/3) 0 1 2 3 0123456789012345678901 +++++++++++++++++++++++ | Type | Length

The Format of message(3/3) 0 1 2 3 0123456789012345678901 +++++++++++++++++++++++ | Type | Length | Prefix Length | Resvd|Prf|Resvd| +++++++++++++++++++++++ | Router Lifetime | +++++++++++++++++++++++ | Prefix (Variable Length) |. . +++++++++++++++++++++++

Conceptual Model of Host n n n Type A: Neighbor Discovery. Type B: Hosts

Conceptual Model of Host n n n 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.

Example : : /0 -> router W with a Medium prefrence 2002: : /16

Example : : /0 -> router W with a Medium prefrence 2002: : /16 -> router X with a Medium preference 2001: db 8: : /32 -> router Y with a High preference 2001: db 8: : /32 -> router Z with a Low preference

Reference RFC 4191 Default Router Preferences and More-Specific Routes n http: //www. faqs. org/rfcs/rfc

Reference RFC 4191 Default Router Preferences and More-Specific Routes n http: //www. faqs. org/rfcs/rfc 4191. html RFC 3775 Mobility Support in IPv 6 n http: //www. faqs. org/rfcs/rfc 3775. html RFC 2461 Neighbor Discovery for IP Version 6 n http: //www. faqs. org/rfcs/rfc 2461. html