ICND 1 - Chapter 6

-Packet is created on host-Packet is forwarded to default gateway if not on local network-If default gateway's hardware address is not known, arp request sent.-Frame is created with FCS, destination address of default gateway, source address of host.-Router receives packet and checks routing table for network of destination address - if it doesn't find one it will drop the packet.-If it finds an entry in the table, the router, changes the packet to a frame and arps for the destination host if it doesn't have one. Once it has an entry it forwards the packet.-Remote host receives packet, checks CRC to make sure it matches. Remote host becomes source host and sends packet back.

Maximum Hop Count - max count of 15 for hopsSplit Horizon - do not allow routing updates to go out the same interface they come inRoute Poisoning - Poisoning by advertising route that goes down as unreachable, preventing mistaken updates. Poison reverse ensures that all routes have received the updateHolddowns - timer to allow downed routes to recover, restrict updates to recently removed routes

Route update timer - Sets the interval (typically 30 seconds) between periodic routing updatesin which the router sends a complete copy of its routing table out to all neighbors.
Route invalid timer - Determines the length of time that must elapse (180 seconds) before arouter determines that a route has become invalid. It will come to this conclusion if it hasn’theard any updates about a particular route for that period. When that happens, the routersends out updates to all its neighbors letting them know that the route is invalid.
Holddown timer - This sets the amount of time during which routing information is suppressed.Routes enter into the holddown state when an update packet is received that indicatesthe route is unreachable. This continues either until an update packet is received with a bettermetric or until the holddown timer expires. The default is 180 seconds.
Route flush timer - Sets the time between a route becoming invalid and its removal from therouting table (240 seconds). Before it’s removed from the table, the router notifies its neighborsof that route’s impending demise. The value of the route invalid timer must be less thanthat of the route flush timer. This gives the router enough time to tell its neighbors about theinvalid route before the local routing table is updated.

Ip route 172.16.10.0 255.255.255.0 172.16.20.1

If the box next to an interface is unchecked, this means that passive-interface will not beused and RIP will be sent and received on that interface.

Ip route 0.0.0.0 0.0.0.0 172.16.40.1

Router(config)#ip classless

Stub network

Show ip route

Exit interface

False

True

Clock rate 64000

Conf trouter ripnetwork 10.0.0.0

Router rip, passive-interface s1