Each router maintains a map of the overall network and update it when changes happen

Each router passes on its routing table to its neighboring routers

Neighboring routers integrate this information into their own routing tables

Neighboring routers, in turn pass their updated routing tables on to their neighbors and the process repeats

The routing table is just like a highway sign board that shows the identity of remote cities, the distance to each city and the direction you should take to reach them

The routing table gives you the complete path to take to reach the destination

Distance vector routers have complete knowledge of the entire network

Distance vector routers do not have complete knowledge of the entire network

Network, Via. Mask

Network, Mask, Cost

Network, Cost, Via

Network, Mask, Via

If a router learns about a network from its neighbor, it must advertise this information back to the same router after 240 seconds

If a router learns about a network from its neighbor, it must advertise this information back to the same router after 180 seconds

If a router learns about a network from its neighbor, it must never advertise this information back to the same router

If a router learns about a network from its neighbor, it must immediately pass this information back to the same router

The time interval after which a router will update a particular route if it an update is received on that route

The time interval after which a router will remove a particular route if an update has not been received about that route

The time interval after which a router passes updated information to its neighbors

The time interval after which a router removes all routing information from its routing table

If no route update has been received in 240 seconds, the router can treat the missing routes as "suspicious".

If no route update has been received in 180 seconds, the router can treat the missing routes as "suspicious".

Router will not advertise the suspicious routes to other routers, but it will keep using them itself

Routers will advertise suspicious routes to other routers, but it will not use them itself

The route poisoning technique does not help the network to reach convergence more quickly

When routes disappear, instead of not telling its neighbors, the missing route is poisoned with the cost value of "infinity"

The poisoned route is passed on quickly, instead of each router having to wait for their hold-down timers to expire

The route poisoning technique helps the network to reach convergence more quickly

If a router learns a route from a neighbor, it must not advertise this back to its neighbor

If a router learns a route from a neighbor, it must advertise this back to its neighbor but with an infinite cost

If a route disappears this route is poisoned with a cost value of "infinity".

Poisoned route now is passed on quickly, instead of each router having to wait for their hold-down timers to expire.

There are only three sizes of networks: /8, /16 and /24

If you want to set up a WAN link between two routers, it has to be a /30 (Class-C) network

if routes are learned dynamically, routers have to assume the network size is either /8, /16 or /24.

Routers can get confused with route advertisements because they have to assume the network size (discontinuous networks)

RIP version 1

RIP version 2

EIGRP

OSPF

RIP is a Link State Protocol, the cost metric for the protocol is "hop count"

RIP does not take in to consideration the speed or other qualities of the links

RIPv2 send advertisements out using the multicast address 224.0.0.9

When a RIPv2 router receives an advertisement, it adds on the cost of each link, which is always +1.

Split Horizon with Poison Reverse

Poison Reverse with Flush Timers

Split Horizon with Flush timers

Hold-down timers

interface rip

router rip

show ip route

interface vlan rip

debug rip

debug ip rip

debug

show debug