23 - Implementing OSPF for IPV6

Question 1

Which 2 commands should be on every router running OSPFv3 for IPv6?

Answer 1

• ipv6 router ospf 2 * interface subcommand ‘ipv6 ospf 2 area 23’

Question 2

What determines if an interface can be made passive?

Answer 2

no expectation to find an OSPF neighbor on that data link

Question 3

What 3 show cmds tell you about the interfaces with OSPFv3 enabled?

Answer 3

• show ipv6 protocols * show ipv6 ospf interface brief * show ipv6 ospf interface

Question 4

What is the number one place to look for OSPF problems?

Answer 4

issues that prevent routers from becoming neighbors

Question 5

What 4 show cmds tell you about the neighbor relationships?

Answer 5

• show ipv6 ospf interface * show ipv6 ospf interface brief * show ipv6 protocols * show ipv6 ospf

Question 6

In OSPF neighbors need to have equal MTU sizes. What is the show command to determine if this is the case?

Answer 6

show ipv6 interface

Question 7

What is an Inter-area route?

Answer 7

A route that is in a different area

Question 8

What is an intra-area route?

Answer 8

A route that is in the same area

Question 9

What are the 3 ways to configure the router_ID?

Answer 9

• router-id (value) * configure highest IPv4 address on loopback * rely on highest non-loopback IPv4 address

Question 10

What are the 4 basic configuration steps?

Answer 10

• ipv6 router ospf (process_id) * configure router ID * ipv6 ospf (process) area (area_#) * configure any passive interfaces with router subcommand passive-interface gig0/0

Question 11

What are 3 ways to change the interface cost used for route calculation?

Answer 11

• in interface mode, ipv6 ospf cost (cost) * use ‘bandwidth (speed) cmd on interface * router subcommand ‘auto-cost reference-bandwidth (ref_bw)”

Question 12

What router subcommand might impact the number of equal cost routes a router might use?

Answer 12

router subcommand, ‘maximum paths 6’

Question 13

What happens if the wrong area # is used on the interface cmd ‘ipv6 ospf 1 area 3’

Answer 13

A neighbor relationship on that interface won’t form.

Question 14

What 2 things prevent a neighbor relationship from being formed off an interface?

Answer 14

• wrong area number configured * passive-interface configured for that interface

Question 15

What is the difference in neighbor states between ‘adjacent’ and ‘fully adjacent’?

Answer 15

Fully adjacent means the neighbor state reaches the FULL state, adjacent means that routers with DR and BDRs stabilize at 2-way meaning they are adjacent

Question 16

What is the command to restart OSPF?

Answer 16

clear ipv6 ospf process

Question 17

What command shuts down the OSPF process without erasing any OSPF configuration?

Answer 17

router subcommand ‘shutdown’

Question 18

What command changes the MTU size?

Answer 18

interface subcommand ‘ipv6 mtu 1500’ with 1500 being the default

Question 19

What will happen if two OSPF neighbors have mismatching MTU size?

Answer 19

The 2 routers will become neighbors, reach the EXSTART state, being to exchange LSAs but never finish. Then the neighbor state fails to DOWN state.