IPv4 Routing Flashcards
What is a routing table
is a list of routes to known networks. This information is gathered from directly connected networks, static routes, and dynamic routing protocols.
What is a routing source with the code L
Local router interface
What is a routing source with the code C
a directly connected network
What is a routing source with the code S
a static route used to reach a certain network
What is a routing source with the code P
a dynamic network learned using the OSPF routing protocol
What is a routing source with the code R
a dynamic network learned using the RIP routing protocol
What is Administrative distance
is a description of the trustworthiness or preferability of a route
What is Prefix and prefix length
The network address and subnet address for the destination route
What is a metric
identifies how far away the destination is, either in distance or time. The lower the metric, the higher the preference of the route.
What is next-hop
The next-hop is the IP address of the next router that the packet will be forwarded to.
What is the Route timestamp
The route timestamp indicates how much time has passed since the route was learned.
What is the Exit interface
The interface used for sending packets to their destination.
What is the longest match when it comes to routers
Its the route (IP address) that has the most matching bits from left to right
Once the router has calculated the best path, describe what would happen if it chose the Directly connected networks
the router will forward the packet to the directly connected device on that network.
Once the router has calculated the best path and chooses the Remote network what will happen next
the router will forward the packet to a next-hop router. Remote routes can be added to the routing table manually or dynamically. Manually added routes are referred to as static routes
Once the router has chose the default route what happens next
If there is no match found in the routing table, the packet will be dropped. This can be avoided by setting a default route in hopes that the next device will have more information on the intended destination. Default routes can be entered manually or can be obtained via dynamic routing protocols.
What is Packet forwarding
to place packets into the correct data link frame type for the outgoing device.
What is the first step in the packet forwarding decision process
The data link frame arrives with an encapsulated IP address
What is the second step in the packet forwarding decision process
The router examines the destination address and refers to its routing table
What is the third step in the packet forwarding decision process
The router finds the longest match in the routing table
What is the fourth step in the packet forwarding decision process
The router encapsulates the packet in a frame with the updated routing information
What is the fifth step in the packet forwarding decision process
If there is no matching route entry, the packet is dropped
Describe process switching
the earliest Cisco route processing implementation. Process switching required the router to process each received frame individually using the steps outlined above.
Describe fast switching
processes packets in the same manner as process switching; however, it incorporates several mechanisms designed to optimize the process, caches frequently used data link headers and recently used destinations.
Describe Cisco Express Forwarding (CEF)
an advanced routing mechanism designed to optimize packet processing in very large networks. CEF increases packet switching speed and reduces the overhead introduced by other routing techniques
What is administrative distance
a value used to rank route sources
How many points does the Connected route source have
0
How many points does the Static route source have
1
How many points does the EIGRP route source have
5
How many points does the External BGP route source have
20
How many points does the Internal EIGRP route source have
90
How many points does the IGRP route source have
100
How many points does the OSPF route source have
110
How many points does the IS-ISroute source have
115
How many points does the RIP route source have
120
How many points does the External EIGRP route source have
170
How many points does the Internal BGP route source have
200
