Flashcards
Routing - Test 1 Revision
Cards in this deck (27)
- 1What is forwarding?Taking one packet from one network and putting it on another network
- 2How does forwarding work?Looks at the routing table for forwarding instructions
e.g. what is the next hop this packet should go on - 3What is Routing?The process of building the routing table in which the router can use to forward packets onto another network
Learning what the network looks like and building a table that the router can look at to consider for sending packets through the network
Deciding what the best path to forward packets is - 4How does routing work?It learns where to put packets, which will have the shortest cost path which packets can take to get somewhere
- 5What does a router do if the network changes? i.e a new link is addedIt will then figure out what the new best paths through the network and adjust the routing tables appropriately
- 6What is the key difference between a router and a host?A router is connected to multiple networks and host is only connected to one
- 7How do we choose the best/optimal route?-Shortest Path First Algorithm
-Shortest path by delay and/or jitter
-Highest bandwidth
-Least number of hops - 8Why you static routing?Simple. you have full control of the routing because theres no automation involved, so it wont change on you, it requires no impact in signalling
- 9What is the Interior Gateway Protocol (IGP)?A routing protocol that is used inside an organisations network (except if a network is so small it can just use static routing)
Often assumed that all routers have full knowledge about the internal topology of the network and they aim to choose the best/optimal network paths
e.g. OSPF - 10What is the Exterior Gateway Protocol (EGP?Used between organisations, this is influenced by less optimal network topology and more by business decisions
- 11IGP Class Type: Link-State?In a link state, all the routers build a graph of the network themselves and then decide what the best paths are independantly
- 12What is Dijkstras Path?Shortest Paths First, each router in the network is assumed to have the same view of the network as any other router in that same network, they all understand what the network topology is and then each node independently computes what the shortest path is to all prefixes that are announced in the network, if multiple paths are found they can all be found and all be used, if a new link is found or broken the algorithm is rerun
- 13What is the Bellman Ford Algorithm?Instead of all nodes having full knowledge of the network topology, we advertise what nodes or prefixes can be reached through us (i.e. Distance Vector)
- 14What happens in the bellman ford algorithm when a link fails?A failed route is not advertised, other nodes will only know if theres a failure when they receive an advertisement without the route
- 15What is counting to infinity?nodes do not know if a received path includes them, e.g. A link between C and D has failed, C has detected there isnt an open link there anymore and its going to withdraw the route, but C then receives a message from B saying it can reach D then C adds that route in it, then same thing happens with another node and so on infinitely
- 16How do you fix the counting to infinity problem?Just to say the max network size/distance across the network that can be computed with the Bellman Ford Algorithm to some low value, so the route will be invalid and discarded, but this limits the size of the network
- 17What is split horizon?A solution to count to infinity
If you receive a route from a neighbour, you wont tell the neighbour about the route that youve also received - 18What is poison reverse?A solution to count to infinity
When a neighbouring node becomes unavailable, set its max size to infinity then if the max size is 15 the route will be discarded - 19What is RIP?RIP Routing Information Protocol
Classic Distance-Vector Interior Gateway Protocol - uses Bellman Ford Algorithm - 20What are the two loopback addresses for IPv4 and IPv6?IPv4: 127.0.0.1
IPV6: ::1 - 21What are the two classes for the Internal Gateway Routing Protocol?Link State and Distance Vector
- 22IGP Class Type: Distant-Vector?All routers inform eachother of changes i.e when there are new paths/paths are broken
- 23Which IGP class does the Bellman Ford Algorithm use?Distance-Vector Class
- 24Which IGP class does Dijkstras Algorithm Use?Link-State Class
- 25Which algorithm does Link-State use?Dijkstras Algorithm
- 26Which algorithm does Distance-Vector use?Bellman Ford Algorithm
- 27—
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- Flashcards on Routing - Test 1 Revision, created by Cherese Eriepa on 11/04/2018.
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- Cherese Eriepa
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