Transcript 1.What are the two main ways of classifying dynamic IGP

Pre-Assessment Quiz
Produced by
Mohamed BEN HASSINE
CNA Instructor
The American University of Paris
CCNA3 ’s PAQ
PAQ
•Distance-vector
•Link-state
CCNA3 ’s PAQ
1. What are the two main ways of classifying
dynamic IGP routing protocols?
Link-state, because that’s exactly what they
do: they look for the shortest path to the
destination (regardless of whether or not
this is the BEST path).
CCNA3 ’s PAQ
2. Which ones are also known as “shortest
path first” protocols? Why?
3. Fill in the following table:
Protocol(s)
Distance Vector

Link State
Advantage(s)
Disadvantage(s)
CCNA3 ’s PAQ
Type
Protocol(s)
Distance Vector
 RIPv1

Link State
Advantage(s)
Disadvantage(s)
CCNA3 ’s PAQ
Type
Protocol(s)
Distance Vector
 RIPv1
 RIPv2

Link State
Advantage(s)
Disadvantage(s)
CCNA3 ’s PAQ
Type
Protocol(s)
Distance Vector
 RIPv1
 RIPv2
 IGRP

Link State
Advantage(s)
Disadvantage(s)
CCNA3 ’s PAQ
Type
Protocol(s)
Distance Vector





Link State
RIPv1
RIPv2
IGRP
OSPF
Advantage(s)
Disadvantage(s)
CCNA3 ’s PAQ
Type
Protocol(s)
Advantage(s)
Distance Vector






Link State
RIPv1
RIPv2
IGRP
OSPF
IS-IS
Disadvantage(s)
CCNA3 ’s PAQ
Type
Protocol(s)
Advantage(s)
Distance Vector





 Easy to configure

Link State
RIPv1
RIPv2
IGRP
OSPF
IS-IS
Disadvantage(s)
CCNA3 ’s PAQ
Type
Protocol(s)
Advantage(s)
Disadvantage(s)
Distance Vector





 Easy to configure
 Updates regularly

Link State
RIPv1
RIPv2
IGRP
OSPF
IS-IS
CCNA3 ’s PAQ
Type
Protocol(s)
Advantage(s)
Disadvantage(s)
Distance Vector
 RIPv1
 RIPv2
 IGRP
 Easy to configure
 Updates regularly
 Takes up
significant
bandwidth

Link State
 OSPF
 IS-IS
CCNA3 ’s PAQ
Type
Protocol(s)
Advantage(s)
Disadvantage(s)
Distance Vector
 RIPv1
 RIPv2
 IGRP
 Easy to configure
 Updates regularly
 Takes up
significant
bandwidth
 Slow to converge

Link State
 OSPF
 IS-IS
CCNA3 ’s PAQ
Type
Protocol(s)
Advantage(s)
Disadvantage(s)
Distance Vector
 RIPv1
 RIPv2
 IGRP
 Easy to configure
 Updates regularly
 Takes up
significant
bandwidth
 Slow to converge
 Subject to routing
loops

Link State
 OSPF
 IS-IS
CCNA3 ’s PAQ
Type
Protocol(s)
Advantage(s)
Disadvantage(s)
Distance Vector
 RIPv1
 RIPv2
 IGRP
 Easy to configure
 Updates regularly
 Takes up
significant
bandwidth
 Slow to converge
 Subject to routing
loops
 RIP only has 1
metric

Link State
 OSPF
 IS-IS
CCNA3 ’s PAQ
Type
Protocol(s)
Advantage(s)
Disadvantage(s)
Distance Vector
 RIPv1
 RIPv2
 IGRP
 Easy to configure
 Updates regularly
 Takes up
significant
bandwidth
 Slow to converge
 Subject to routing
loops
 RIP only has 1
metric
 Only RIP v. 2 can
use VLSM
Link State
 OSPF
 IS-IS

CCNA3 ’s PAQ
Type
Protocol(s)
Advantage(s)
Disadvantage(s)
Distance Vector
 RIPv1
 RIPv2
 IGRP
 Easy to configure
 Updates regularly
 Takes up
significant
bandwidth
 Slow to converge
 Subject to routing
loops
 RIP only has 1
metric
 Only RIP v. 2 can
use VLSM
Link State
 OSPF
 IS-IS
 Only sends out updates as
needed

CCNA3 ’s PAQ
Type
Protocol(s)
Advantage(s)
Disadvantage(s)
Distance Vector
 RIPv1
 RIPv2
 IGRP
 Easy to configure
 Updates regularly
 Takes up
significant
bandwidth
 Slow to converge
 Subject to routing
loops
 RIP only has 1
metric
 Only RIP v. 2 can
use VLSM
Link State
 OSPF
 IS-IS
 Only sends out updates as
needed
 Doesn’t use much bandwidth to
maintain tables

CCNA3 ’s PAQ
Type
Protocol(s)
Advantage(s)
Disadvantage(s)
Distance Vector
 RIPv1
 RIPv2
 IGRP
 Easy to configure
 Updates regularly
 Takes up
significant
bandwidth
 Slow to converge
 Subject to routing
loops
 RIP only has 1
metric
 Only RIP v. 2 can
use VLSM
Link State
 OSPF
 IS-IS
 Only sends out updates as
needed
 Doesn’t use much bandwidth to
maintain tables
 Fast to converge

CCNA3 ’s PAQ
Type
Protocol(s)
Advantage(s)
Disadvantage(s)
Distance Vector
 RIPv1
 RIPv2
 IGRP
 Easy to configure
 Updates regularly
 Takes up
significant
bandwidth
 Slow to converge
 Subject to routing
loops
 RIP only has 1
metric
 Only RIP v. 2 can
use VLSM
Link State
 OSPF
 IS-IS
 Only sends out updates as
needed
 Doesn’t use much bandwidth to
maintain tables
 Fast to converge
 Not subject to routing loops

CCNA3 ’s PAQ
Type
Protocol(s)
Advantage(s)
Disadvantage(s)
Distance Vector
 RIPv1
 RIPv2
 IGRP
 Easy to configure
 Updates regularly
 Takes up
significant
bandwidth
 Slow to converge
 Subject to routing
loops
 RIP only has 1
metric
 Only RIP v. 2 can
use VLSM
Link State
 OSPF
 IS-IS
 Only sends out updates as
needed
 Doesn’t use much bandwidth to
maintain tables
 Fast to converge
 Not subject to routing loops
 Knows complete topology of
network so knows all routes

CCNA3 ’s PAQ
Type
Protocol(s)
Advantage(s)
Disadvantage(s)
Distance Vector
 RIPv1
 RIPv2
 IGRP
 Easy to configure
 Updates regularly
 Takes up
significant
bandwidth
 Slow to converge
 Subject to routing
loops
 RIP only has 1
metric
 Only RIP v. 2 can
use VLSM
Link State
 OSPF
 IS-IS
 Only sends out updates as
needed
 Doesn’t use much bandwidth to
maintain tables
 Fast to converge
 Not subject to routing loops
 Knows complete topology of
network so knows all routes
 Uses cost metrics instead of
distance metrics

CCNA3 ’s PAQ
Type
Protocol(s)
Advantage(s)
Disadvantage(s)
Distance Vector
 RIPv1
 RIPv2
 IGRP
 Easy to configure
 Updates regularly
Link State
 OSPF
 IS-IS
 Only sends out updates as
needed
 Doesn’t use much bandwidth to
maintain tables
 Fast to converge
 Not subject to routing loops
 Knows complete topology of
network so knows all routes
 Uses cost metrics instead of
distance metrics
 Can use VLSM and CIDR
 Takes up
significant
bandwidth
 Slow to converge
 Subject to routing
loops
 RIP only has 1
metric
 Only RIP v. 2 can
use VLSM

CCNA3 ’s PAQ
Type
Protocol(s)
Advantage(s)
Distance Vector
 RIPv1
 RIPv2
 IGRP
 Easy to configure
 Updates regularly
Link State
 OSPF
 IS-IS







Disadvantage(s)
 Takes up
significant
bandwidth
 Slow to converge
 Subject to routing
loops
 RIP only has 1
metric
 Only RIP v. 2 can
use VLSM
Only sends out updates as
 Difficult to
needed
configure
correctly
Doesn’t use much bandwidth to
maintain tables

Fast to converge
Not subject to routing loops
Knows complete topology of
network so knows all routes
Uses cost metrics instead of
distance metrics
Can use VLSM and CIDR
CCNA3 ’s PAQ
Type
Protocol(s)
Advantage(s)
Distance Vector
 RIPv1
 RIPv2
 IGRP
 Easy to configure
 Updates regularly
Link State
 OSPF
 IS-IS







Disadvantage(s)
 Takes up
significant
bandwidth
 Slow to converge
 Subject to routing
loops
 RIP only has 1
metric
 Only RIP v. 2 can
use VLSM
Only sends out updates as
 Difficult to
needed
configure
correctly
Doesn’t use much bandwidth to
maintain tables
 Requires more
memory and
Fast to converge
more powerful
Not subject to routing loops
CPUs in routers
Knows complete topology of

network so knows all routes
Uses cost metrics instead of
distance metrics
Can use VLSM and CIDR
CCNA3 ’s PAQ
Type
Protocol(s)
Advantage(s)
Distance Vector
 RIPv1
 RIPv2
 IGRP
 Easy to configure
 Updates regularly
Link State
 OSPF
 IS-IS







Disadvantage(s)
 Takes up
significant
bandwidth
 Slow to converge
 Subject to routing
loops
 RIP only has 1
metric
 Only RIP v. 2 can
use VLSM
Only sends out updates as
 Difficult to
needed
configure
correctly
Doesn’t use much bandwidth to
maintain tables
 Requires more
memory and
Fast to converge
more powerful
Not subject to routing loops
CPUs in routers
Knows complete topology of
 Takes a lot of
network so knows all routes
bandwidth when
Uses cost metrics instead of
first started
distance metrics
Can use VLSM and CIDR
CCNA3 ’s PAQ
Type
• Link state protocols use them to make
sure a link is still active. They’re very
small packets.
CCNA3 ’s PAQ
4. What are “hello” packets used for?
•
•
•
•
•
Link-state advertisements (LSAs)
A topological database
The shortest path first (SPF) algorithm
The resulting SPF tree
A routing table of paths and ports to
each network to determine the best
paths for packets
CCNA3 ’s PAQ
5. What are the five things that link state
protocols use to maintain their tables:
• A link is an interface on a router.
CCNA3 ’s PAQ
6. What is meant by a “link” when talking
about link state protocols?
• It’s a database of the entire topology of
the network and includes each link and
how to reach it. It’s built by using the
LSAs that have been received by the
router.
CCNA3 ’s PAQ
7. How does a link state protocol build its
topological database? What kind of
information is in it?
• Nonbroadcast multi-access (NBMA),
such as frame relay
• Broadcast multi-access, such as
Ethernet
• Point-to-point networks
CCNA3 ’s PAQ
8. What are the three types of networks
recognized by OSPF?
• DR – Designated Router acts as the
“brains” of the network. This router
makes sure that all the LSAs are sent to
all the other routers in the Area.
• BDR – Backup Designated Router acts
as the “second in command” of the
network. If the DR goes down, the BDR
takes over as DR. However, until the DR
goes down, the BDR does not send out
LSAs to any other routers in the Area.
CCNA3 ’s PAQ
9. What is the DR and the BDR in an
OSPF network? What do they do?
• 224.0.0.5
• 224.0.0.6
CCNA3 ’s PAQ
10. What is the multicast address used by
the DR to send out LSAs to all other OSPF
routers? For LSAs just to other
designated (and backup) routers?
• A hello packet is the way OSPF routers
make sure that a link is still active.
224.0.0.5 is the address used so that all
links are checked, not just DRs and
BDRs.
CCNA3 ’s PAQ
11. What is a hello packet used for
and what is the multicast address
used for it? Why this address?
• 10 seconds
CCNA3 ’s PAQ
12. What is the default hello interval?
• Area 0 (zero)
CCNA3 ’s PAQ
13. What is the main area of an OSPF
network designated?
• Router(config)#router ospf [process ID]
CCNA3 ’s PAQ
14. What is the command used to start
OSPF routing on a router?
• It’s an identifier for the OSPF routing
process on the router
CCNA3 ’s PAQ
15. What is the processor ID?
• Router(config-router)#network [network
no.] [wildcard-mask] area [area-id]
CCNA3 ’s PAQ
16. What is the command used to identify
networks on an OSPF router?
• It uses the highest active IP address on
any of the interfaces (where OSPF is
running). If you want to change the ID,
set a Loopback interface with a higher IP
address so it will be forced to be the ID.
CCNA3 ’s PAQ
17. What does an OSPF router use for its
router ID? How can you force a different
ID?
• It is a logical (virtual) interface; not a
physical (real) one
CCNA3 ’s PAQ
18. What is a Loopback?
• Router(config)#int Loopback[No.]
• Router(config-if)#ip addr [IP number]
[subnet mask]
CCNA3 ’s PAQ
19. What is the command used to set a
Loopback?
• 255.255.255.255
CCNA3 ’s PAQ
20. What is the recommended subnet
mask to use on a Loopback interface?
• If there is more than 1 router in the Area
(broadcast multi-access), then there must be a
DR and maybe a BDR for the Area. The priority
number is used to determine which routers will
be the DR and the BDR.
You can change it with the following command:
Router(config-if)#ip ospf [priority number]
CCNA3 ’s PAQ
21. What is a “priority” number used for?
How can you change it?
• Cost (the default metric of OSPF) uses
bandwidth to determine the best route. The
default is 1.544 Mbps. You can change it with
the command:
• Router(config)#interface [type] [number]
• Router(config-if)#bandwidth [Kbps]
CCNA3 ’s PAQ
22. Why must you set the bandwidth on
an interface running OSPF? What is the
default bandwidth? How can you change
it?
• They exchange passwords that only other
OSPF routers will know. Use the commands
below to set authentication:
• Router(config-if)#ip ospf authentication-key
[password]
• Router(config-router)#area [area-number]
authentication
CCNA3 ’s PAQ
23. How can OSPF routers authenticate
each other?
• The default authentication sends the
password in plain text; message-digest
encrypts the password that’s sent.
• Router(config-if)#ip ospf authentication
message-digest-key [key-id] md5
[encryption-type key]
• Router(config-router)#area [area-id]
authentication message-digest
CCNA3 ’s PAQ
24. What is the difference between default
authentication and a message-digest
authentication procedure? What is the
command to do the latter?
• The dead interval is 4 times the hello interval
(e.g., hello is 10 seconds, so dead is 40
seconds).
• The dead interval is the time used to determine
that a link is down, or dead. In other words, if a
hello isn’t received from a link for the space of
4 times the normal hello interval, it’s
considered dead.
CCNA3 ’s PAQ
25. What is the relationship between the
“hello” packet interval and the “dead”
interval? What is meant by the “dead”
interval?
• They wouldn’t be able to “talk” to each other,
so would be considered inactive. Hello
intervals must be the same on all the routers in
the network.
CCNA3 ’s PAQ
26. What would happen if routers in the
OSPF network have different hello
intervals configured?
• Use the “quad zero” command:
Router(config)#ip route 0.0.0.0 0.0.0.0 [interface
or IP address of next hop]
CCNA3 ’s PAQ
27. What is the best way to define a
default route on an OSPF router?
• Router(config-router)#default-information
originate
CCNA3 ’s PAQ
28. How can you make sure that this
information is propagated to other routers
in the area?
•
•
•
•
•
Show ip route
Show ip protocol
Show ip ospf interface
Show ip ospf
Show ip ospf neighbor [detail] (shows
neighbor database)
• Show ip ospf database (shows topological
database)
CCNA3 ’s PAQ
29. List some of the show commands you
can use to make sure that OSPF is
functioning correctly.