Chapter 3-5: Adjust and Troubleshoot Single-Area OSPF Flashcards Preview

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Flashcards in Chapter 3-5: Adjust and Troubleshoot Single-Area OSPF Deck (25)
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1
Q

What are five [5] network types of OSPF Network.

A
  1. Point-to-point – WAN links
  2. Broadcast Multiaccess – Ethernet network
  3. NBMA (non-broadcast multiple access network ) – Frame Relay, ATM or x.25
  4. Point-to-multipoint – hub-and-spoke topology over NBMA
  5. Virtual links – connect distant OSPF areas to the backbone
2
Q

What are two [2] challengers for multiaccess Network?

A
  1. Multiple adjacencies

2. Extensive LSA Flooding - every LSA must be ACKed

3
Q

What are two [2] solutions for LSA flooding issue

A
  1. Designated router (DR)

2. Backup DR (BDR)

4
Q

What are the IPv4 and IPv6 address for sending and receiving LSA

A

Designated router (DR) other to:
IPv4 224.0.0.6
IPv6 FF02::05

5
Q

What are five [5] reasons that a OSPF Designated Router is used?

A
  1. The DR helps manage adj and flooding on multi-access nets
  2. The BDR is elected in case the DR fails
  3. All other routers become DROTHERs; form adj with the DR/BDR
  4. DR/BDR elections take place only on multi-access networks
  5. They DO NOT occur in point to point networks
6
Q

What are the four [4] states of neighbours in multi-access networks

A
  1. FULL/DROTHER
  2. FULL/DR
  3. FULL/BDR
  4. 2-WAY/DROTHER
7
Q

What are the three [3] Default DR/BDR Election Process

A
  1. The router with the highest interface priority is elected as the DR
  2. The router with the 2nd highest interface priority → BDR
  3. Priority range: 0-255 (0 → cannot become the DR, 255 → usually only two “best” routers set to this value )
8
Q

DR remains the DR until one of the following three [3] issues occurs

A
  1. The DR fails
  2. The OSPF process on the DR fails or is stopped
  3. The multi-access interface on the DR fails or is shutdown
9
Q

What two [2] things happens with the DR (Designated router) fails?

A
  1. The BDR (backup Designated Router ) is automatically promoted to DR (Designated Router)
  2. There is then a new BDR election and the DROTHER with the higher priority or router ID is elected as the new BDR
10
Q

What are three [3] types of authentication of OSPF secure routing?

A
  1. Null – no authentication
  2. Simple password authentication – plain text (outdated)
  3. MD5 – Most secure and recommended method
11
Q

What are seven [7] reasons why adjacencies will not form?

A
  1. Interfaces are not on same network
  2. Network types no identical
  3. Hello or Dead timers don’t match
  4. Passive interfaces are set
  5. There are missing/incorrect network commands
  6. Authentication is mis-configured
  7. RouterID is missing or duplicated
12
Q

What are the Seven [7] Transitioning via OSPF States

A
  1. Down – no Hellos received
  2. Init – Hello’s received, but not with my RouterID
  3. 2-Way → Adjacency ← DR Elections happen
  4. Exstart – Master/Slave relationship established
  5. Exchange – LSDBDs exchanged
  6. Loading – LSUs exchanged
  7. Full – convergence
13
Q

Command to configure MD5 on a per-interface basis

A

ip ospf message-digest-key md5

ip ospf authentication message-digest

14
Q

Describe the down state

A

No Hellos received

15
Q

Describe the init state

A

Hello received but not with my RouterID

16
Q

Describe the 2-way state

A

DR Elections take place

17
Q

Describe the Exstart state

A

Master/slave relationship established

18
Q

Describe the Exchange state

A

LS DBD exchanged

19
Q

Describe the Loading state

A

LSU exchanged

20
Q

Describe the Full state

A

Fully converged

21
Q

Command to show adjacencies

A

show ip ospf neighbour

22
Q

Command to show process ID and router ID

A

show ip ospf

23
Q

Command to show OSPF learned routes

A

show ip route ospf

24
Q

Command to show process ID, timers, DR/BDR info

A

Show ip ospf interface

25
Q

Command to rest adjacency

A

clear ip ospf process