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35 Cards in this Set
- Front
- Back
If you see OSPF in wireshark what would the ip packet look like? |
protocol ID 89 |
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What command allows you to look at the ospf packet in your router? |
debug ip ospf packet |
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V:2
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stands for OSPF version 2. If you are running IPv6 you will use version 3.
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T:1 |
stands for OSPF packet number 1 which is a hello packet |
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L:48 |
is the packet length in bytes
NOTE: This packet is 48 bytes |
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RID 1.1.1.1 |
This is the router ID |
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CHK 4D40 |
is the checksum of this OSPF packet so we can check if the packet is corrupt or not |
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AUT:0 |
is the authentication type
0 = No authentication |
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AUT:1 |
is the authentication type
1 = clear text
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AUT:2 |
is the authentication type
2 = MD5 |
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AUK |
if you enable this authentication you'll see some information here |
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Hello |
Neighbor discovery, Build neighbor adjacencies and maintain them |
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DBD |
This packet is used to check if the LSDB between 2 routers is the same. The DBD is summary if the LSDB |
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LSR |
requests specific link-state records from an OSPF neighbor |
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LSU |
Sends specific link-state records that were requested. This packet is like an envelope with multiple LSA in it |
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LSAck |
OSPF is a reliable protocol so we have packet to acknowledge the others |
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AID |
Is the area ID in dotted decimal.
NOTE: You can write the area in decimal (area 0) or dotted decimal |
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Down |
no ospf neighbors detected at this moment |
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Init |
hello packet received |
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Two-way |
own router ID found in received hello packet |
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exstart |
master and slave roles determined |
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exchange |
database description packets (DBD) are sent |
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loading |
exchange of LSRs (Link state request) and LSU (link state update packet) |
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Full |
OSPF routers now have adjacency |
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What are the 7 states OSPF must go through before they become neighbors? |
1. Down 2. Init 3. Two-way 4. Exstart 5. Exhange 6. Loading 7. Full |
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What are the types of OSPF Packets
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1. Hello
2. Database Description (DBD) 3. Link-State Request (LSR) 4. Link-State Update (LSU) 5. Link-State Acknowledgment (LSAck) |
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When an OSPF Router puts an entry in the OSPF neighbor table what OSPF state is it in? |
Init State |
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When an OSPF Router has to respond to an OSPF Router with a hello packet, what OSPF state is it in? |
Two-way
NOTE This is unicast and the neighbor field will include all neighbors |
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If the routers are going into two-way state and you are using a multi-access network. What does an OSPF have to elect? |
A Designated Router (DR) or Backup Designated Router (DR) |
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In exstart how is a master determined? |
The one with the highest router ID |
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What state are routers sending a database description (DBD) with a summary of the Link-State Database (LSDB)? |
Exchange State |
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When are routers in a loading state? |
When the routers start sending a Link-State Request (LSR)
NOTE The other router will send a Link state Update (LSU) |
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What is the packet used to let the neighbor router know they are in the full state? |
LSack |
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When both OSPF routers have synchronized what state are they in? |
Full |
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If you want to see the OSPF adjacency in progress what command can you use? |
debug ip ospf adj |