Routing protocols
What are routing protocols simply put buddy router updating
neighbor routers of their known routes (routers gossiping to each other about
learned routers)
In addition if a router (router 2) neighbor learns of a new
route from one of its other neighbor router 3 that router (router 2) will
update its other neighbor router 1
If new routes are added or added or removed a router will
update its neighbor and the news will travel, then they will work together on
finding the next best route.
Routing protocols will always find the best path depending
on which protocol you use
RIP- works but is
not the greatest, default advertisement timer once every 30 seconds will take
90 seconds to determine dropped route. Metric (the best way to reach a
destination) hop RIPP will use best metric based on hop not bandwidth will
advertise routes over and over again
IGRP - developed
by Cisco as an attempt to improve RIP. Uses a metric of bandwidth instead of
hop. Hello 90 sec dead timeout 270 (not on test)
OSPF - Open
shortest path first the most frequently used of all protocols. OSPF is an open
standard protocol. Default hello 10 sec. Will advertise a route once, and will
only update changes in routes. Since this saves on bandwidth you can speed up
the hello to 2 secs if you like. Metric
for OSPF is called cost the formula for cost is 100/bandwidth (100/1.5)
IS-IS – competitor
for OSPF intermediate system to intermediate system, not commonly used IS-IS is
similar to OSPF but requires significant amount of configuration
EIGRP - Extremely
fast protocol, designed for Cisco routers only the best of RIP (simplicity)
best of OSPF (speed) Metric formula is bandwidth
+ delay + reliability + load of link+ MTU(maximum transmission unit (size of
packet))
BGP – Boarded gateway
protocol Used for the internet, all other protocols are used for the inside of
your net. BGP can handle millions of routes
Administrative
distance is set to a higher value of any routing protocol, it reviews each
protocol and determine which protocol metric is better
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