Routing Technologies Flashcards
What is the routing table priority criteria
- Next hop
- Route specificity
- Administrative distance
- Metric
What is route poisoning
Sets the TTL counter to maxium to get rid of the route
What is split horizon
Doesn’t tell a router about a route it learnt from that router
Why did Cisco create EIGRP when a protocol such as OSPF existing
EIGRP is a far simpler protocol to learn and maintain
All routers in an area have the same…
Topology table
What is the primary method of implementing multiple areas in ospf
To perform route summarisation
What is an ABR
Area border route - connects areas to area 0
What is an ASBR
automonous system boundary router - path out of the system
How does OSPF determine neighbour relationships
- Determine router ID
- Add interfaces to link state database dictated by network command
- Send hello message on chose interface
- Receive hello
- Send reply hello
6, Master/slave relationship determined - DBDs are acknowledge and review
- Neighbours a synchronised
In ospf, how is the route ID determined
Highest active IP address (loopback beats physical)
Better to set manually.
In ospf, how often are hello messages sent on broadcast/p2p networks?
every 10 sec
In ospf, how often are hello messages sent on NBMA networks
every 30 sec
What details are contained in a hello message
i. Router id
ii. Neighbours
iii. Hello and dead timers
iv. Router priority
v. Network mask
vi. DR/BDR ip address
vii. Area ID
viii. Auth password
What 4 details in a hello packet must match in order for OSPF to work.
Hello and dead timers
Network mask
Area ID
Auth password
How are the DR/BDR elected?
Chosen based on higher priority
Can manually set priority but may need to clear ospf process for it to change
What is the broadcast address for DR/BDR
224.0.0.6
Why is it good practice to adjust the reference bandwidth
So OSPF can function in 10Gbps networks
How is the reference BW changed
- Router ospf 1
* Auto-cost reference-bandwidth 10000
What is a passive interface
Stops advertising routes and sending hello messages
What are the two methods of setting a passive interface
Manually select interface and make passive
Make all interfaces passive by default, then enable ospf on interface you want to send hello packets on (cisco preferred as more secured)
What are the default ospf hello/dead timers
10/40
How can the hello timers be changed
ip ospf hello-interval xx
In Multi-area ospf, how are the routes from other ospf areas listed in the routing table.
IA
Why are loopback interfaces used.
Virtual interfaces
can be set for testing, or using a virtual ip
