• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

Card Range To Study

through

image

Play button

image

Play button

image

Progress

1/34

Click to flip

Use LEFT and RIGHT arrow keys to navigate between flashcards;

Use UP and DOWN arrow keys to flip the card;

H to show hint;

A reads text to speech;

34 Cards in this Set

  • Front
  • Back
OSPF: Define LSU
Link state update: packet that holds topology information, LSAs
OSPF: Define LSA

Link state advertisement. Information stored in the link-state database.

OSPF: Define Area
A contiguous grouping of routers and routers interfaces. Routers in an area seek to learn all topology information about that area.
OSPF: Define Area Border Router (ABR)

A router that has interfaces in two distinct OSPF areas, one of which must be the backbone area.

OSPF: Define Backbone Router

A router that has at least one interface connected to the backbone area, area 0.

OSPF: Define Internal Router

A router that has interfaces connected to only one area.

OSPF: Define Designated Router

On multiaccess interfaces (LAN), an OSPF router elected to play the key role in the database exchange process.

OSPF: Define Backup Designated Router
On multiaccess interfaces (LAN) the BDR monitors the DR and is prepared to take over if the DR should fail.
What are the basic IOS commands for configuring OSPF?
#router ospf <process-id>
#network <net-addr> <wildcard> area <x>
What are the three major steps in the OSFP process?
1. Neighbor discovery
2. Topology exchange (full network map)
3. Route computation - SPF algorithm
Do OSPF process-ids need to match in order to become neighbors?
No.
What is the OSPF procedure for choosing a router-id?
1. Specified by #router-id <ip>
2. Highest IP address of up/up loopback interface
3. Highest IP address of up/up interface
What transport protocol is used by OSPF?
IP, protocol type 89. Does not use TCP or UDP
How is the OSPF router metric calculated?
The cumulative cost of all outgoing interfaces in a route. Cost based on bandwidth by default.
On which routers does OSPF support manual route summarization.
Only on ABRs and ASBRs
On which routers does OSPF support auto-summarization
None. Never.
What are the two OSPF timers used to determine convergence?
1. Hello-timer (10 on LAN)
2. Dead timer (4 * Hello)
What are the three OSPF authentication types, and which is the default?
Type 0 = No Authentication (default)
Type 1 = Clear Text
Type 2 = Message Digest (MD5)
What is the maximum length of an OSPF authentication key?
16 characters
Does OSPF support authentication key-chains or time-based keys?
No
What are two ways to create a stable OSPF router id?
1. set with #router-id
2. setup loopback interface
Describe the OSPF Type 1 LSA
Router LSA.
LSID = Router-id
Each router creates 1 for itself and floods through area.
Lists RID and IP addresses on that router.
ABRs create 1 for each area.
Describe the OSPF Type 2 LSA
Network LSA
LSID = DRs IP addr in subnet
Created by DR, for each multiaccess-network (LAN)
LAN represented as a pseudonode, aka transit network
Lists each router connected to pseudonode
What are the rules for electing an OSPF DR and BDR?
1. Highest priority, based on interface mode command #ip ospf priority <n>
2. Highest RID
3. Follow same rules for BDR
When is an OSPF DR/BDR election held?
If no DR/BDR exists, election held.
If DR fails, BDR becomes DR and new election is held for BDR. If BDR fails, same...
No election when priorities change
Describe the OSPF Type-3 LSA
Summary LSA.
LSID = Subnet number
Created by ABR to summarize an area and advertise into other areas.
What are the three internal ospf LSA types?
1. Router
2. Network
3. Summary
How does the OSPF routing algorithm differ for inter-area routes and intra-area routes?
Inter-area routing uses distance-vector logic.
Intra-area routing uses SPF
What is the OSPF formula to calculate an interface cost?
reference-bandwidth K / interface-bandwidth K
What is the default OSPF reference bandwidth?
100 Mbps
What is the command and units to set the OSPF reference bandwidth?
#auto-cost reference-bandwidth <x>
Units are M
What is the command to set the OSPF cost on an interface?
#ip ospf cost <x>
What is the default OSPF cost for a serial sub interface?
Same as the serial interface.
1544
What is the command to set the OSPF bandwidth on an interface?
#bandwidth <x>