RIP

Cette page est une esquisse faite à la va-vite.

RIP est un protocole de routage à vecteur de distance.

RIP version 2 will send triggered updates when the topology changes like when a link goes down.

The following are the key characteristics of RIPv2 pertaining to this question:
1. Split horizon - RIP doesn't advertise routes back out the interface in which they came.
Or put another way, a router won't tell a neighbor about routes that the neighbor presumably already knows about. That would be silly, and could cause a loop in certain circumstances.
2. Triggered update - RIP will send an update out just a soon as the routing table changes. He won't wait for the Update timer to expire.
3. Route poisoning - RIP will tell other routers that a failed route is junk by advertising it with an infinite metric (which is 16 for RIP), effectively poisoning it.
4. Hold down timer : When a destination has become unreachable (or the metric has increased enough to cause poisoning), the destination goes into “holddown”. During this state, no new path will be accepted for the same destination for this amount of time. The hold time indicates how long this state should last.

Exemple de configuration

router rip
 version 2
 !
 ! gestion de la redistribution des routes
 default-metric 1                  ! défini la métrique de redistribution par défaut
 redistribute static
 redistribute ospf 1 metric 3
 !
 ! les interfaces de routage ne seront pas actives en RIP par défaut
 passive-interface default
 no passive-interface Tunnel1
 no passive-interface Vlan5
 !
 ! définition/ajout de coûts sur certaines interfaces
 offset-list 0 in  1 Tunnel1
 offset-list 0 out 1 Tunnel1
 offset-list 0 in  3 Vlan5
 offset-list 0 out 3 Vlan5
 !
 ! réseaux annoncés
 network 10.0.0.0
 !
 ! Contrôle des annonces RIP envoyées et reçues
 distribute-list RIP_out out
 distribute-list RIP_in in
 !
 ! permet de ne pas utiliser les masques CIDR
 no auto-summary
!
ip access-list RIP_out
 permit 10.0.1.0 0.0.0.255 ! réseau 1
 permit 10.0.2.0 0.0.0.255 ! réseau 2
 deny any                  ! par défaut mais explicite c'est mieux
!
ip access-list RIP_in
  permit 192.168.0.0 0.0.0.255 ! réseau d'en face
  deny any