Dynamic Routing Protocols Flashcards
What are the two distance vector protocols?
RIP and EIGRP
What is an example of a link state protocol
OSPF or IS-IS
What is an example of a path vector protocol
BGP
Give an exampe of an EGP
BGP
Give an exampe of an IGP
OSPF, RIP or EIGRP
What are two routes that are automatically added when you connect two routers?
Connected and Local
What is a “Connected” route
A route to a directly connected network
What is a “Local” Route?
A route to a specific host. (The neighbour’s NIC)
How do distance vectors algorithms work?
They send information about a known destination network and the metric to reach it.
What is “routing by rumour”?
In distance vector algorithms, routers only know what they are told by other routers.
How do link state protocols work?
Each router creates the same map of the network. Each router makes its own calculation to find the best route.
What is an advantage of link state protocols over distance vector protocols?
They are faster to react to changes in the network.
What is an advantage of distance vector protocols over link state protocols?
Requires less CPU of the router due to not calculating as much information.
A router dynamically learns two routes. Which does it consider the best?
The route with the lowest metric.
What happens if two routes to the same destination have the same cost?
Both routes will be added to the routing table and the traffic will be load-balanced. This is called ECMP (Equal Cost Multi Path) load balancing.
What is ECMP load balancing?
Equal Cost Multi Path load balancing.
A route’s cost is listed as [110/3] in the routing table. Which is the metric and which is the administrative distance?
AD= 110
Metric = 3
What is a metric?
The cost of a route to a specified network or host
What is administrative distance?
A way for the router to select the best route prior to calculating the metric.
What type of metric does RIP use?
Hop count (links of all speeds are equal).
What type of metric do OSPF and IS-IS use?
Cost (bandwidth based)
What type of metric does EIGRP use?
A complex formula based on bandwidth and delay.
What is the administrative distance of OSPF?
110
What is the administrative distance of static routes?
1
What is the administrative distance of directly connected routes?
0
What is the administrative distance of EIGRP routes?
90
What is the administrative distance of RIP routes?
120
What is the administrative distance of IGRP (old EIGRP) routes?
100
What is the administrative distance of IS-IS routes?
115
Is lower or higher Administrative Distance preferred?
Lower
What is the command to change a route’s administrative distance? And why would you do this?
IP Route ‘network’ ‘subnet mask’ ‘next-hop-ip’ ‘AD’
To make one static route more or less preferred over an another.
What is a floating static route?
A static route which has been configured to have a higher administrative distance than another. Making it the “backup” route.
