Ccnp Route, Chapter 15, 16

Front 1

What is route filtering

Back 1

When we filter routes we can choose which routes we are going to allow in our routing table or what routes we don't want to send our neighbors

Front 2

How is route filtering like an access list?

Back 2

If you don't permit something you will be denied by default

Front 3

What command allow you to see the route filtering options

Back 3

distribute-list

Front 4

What does ge mean?

Back 4

greater than or equal to

Front 5

What does le mean

Back 5

less than or equal to

Front 6

What does a route-map do?

Back 6

They work with match and set statements.

NOTE:
You can use a route-map to match certain criteria and then configure it to take action

Front 7

_________ can be used for BGP Policies and policy based routing (used to over rule routing protocols)

Back 7

route-map

Front 8

"match ip" command does ________?

Back 8

allows you to match an address or even next-hop or route-source address

Front 9

Can a router determine the difference between traffic that is originating from the router and traffic that is flowing through the router?

Back 9

Yes

Front 10

What is the command to activate policy based routing?

Back 10

Router(config)#int fa 0/1

Router(config-if)#ip policy route-map PolicyNameGoesHere

Front 11

What order do route-maps work?

Back 11

They work with sequence numbers. We start at the top and process the statements starting with sequence number 10

Front 12

Can you have multiple match statements in a single sequences with route-map?

Back 12

Yes

Front 13

What is redistribution?

Back 13

With multiple routing protocols on the same network this is a way of exchanging routing information between protocols.

Front 14

What are the 3 main ways of redistribution?

Back 14

• Between Routing Protocols
• Static Routes
• Directly Connected areas

Front 15

What is the redistribute connected command?

Back 15

Another way of connecting routes into a routing protocal

Front 16

What is a seed metric?

Back 16

• OSPF: Cost
• EIGRP: Bandwidth, Delay, Load, Reliability and MTU
• RIP: Hop Count

Front 17

If you redistribute rip what is the default seed metric?

Back 17

Infinity

NOTE:

You have to configure a default hop count for everything you redistribute into RIP or its not going to work

Front 18

What do you have to configure when redistributing EIGRP?

Back 18

• Bandwidth
• Delay
• Load
• Reliability
• MTU

NOTE:

If you do not configure these redistribution will not work

Front 19

What happens to the cost when you redistribute OSPF?

Back 19

The redistributed routes will have a cost of 20 unless the routing information comes from BGP which has a cost of 1

Front 20

Router(config)#router rip

Router(config-router)#default metric 5

What is this command doing?

Back 20

This sets the hop count to 5 for everything we redistribute into RIP

Front 21

What does a reliability of 255 in EIGRP mean?

Back 21

it is 100% reliable

Front 22

What is "One way redistribution"?

Back 22

This is when you redistribute Routing Protocol A into Routing protocol B, but not vice-versa

Front 23

What is "Two way Redistribution?"

Back 23

This is when we redistribute between both routing protocols

Front 24

One Way Redistribution and Two Way Redistribution are both called __________?

Back 24

One Point Redistribution

Front 25

What is "One Point Redistribution"?

Back 25

This is when only one router does the redistributions

Front 26

Why are "One point Redistribution's" Safe?

Back 26

There is only one entrance and one exit from one routing protocol to another.

NOTE:

Because of this we cannot have any loops

Front 27

Two routers that are both performing redistribution is called _______________

Back 27

multipoint redistribution

Front 28

one-way multipoint redistribtion

Back 28

When two or more routers redistribute into a routing protocol and it is not reciprocated

Front 29

Two-Way Multipoint Redistribution

Back 29

Redistribution of routing Protocol A into Routing Protocol B and vice-versa

Front 30

What type of redistribution is very likely to introduce problems such as loops and/or sub-optimal routing?

Back 30

Multipoint Redistribution

Front 31

When you redistribute into EIGRP what administrative distance will it have

Back 31

170

NOTE:
EIGRP sees external routing information as not-so-reliable which is why it will assign it this high administrative distance

Front 32

What is sub-optimal routing

Back 32

For example, when you are redistributing between two routing protocol ex) OSPF/EIGRP, if you don't configure filters or administrative distance modification, then sub-optimal routing may occurs. One of the routing protocol (eigrp) advertise a route to the other routing protocol (ospf) with a better AD even this route is originally in the other routing domain (ospf)

Front 33

Route Flapping

Back 33

This is when the Route availability goes up and down

Front 34

What causes Route Flapping

Back 34

• Unstable Links within the network
• Unstable Neighbor(s) within the network
• Duplicate Router ID within the Network
• Routing protocol has been improperly redistributed and the route is no longer seen

Front 35

4 Guidelines we can use to prevent problems with redistribution

Back 35

• Redistribute only internal routes from routing protocol A to routing protocol B
• Tag routes on routers doing redistribution
• Increase the metric for redistributes routes so internal routes are used instead of redistributed ones
• Change the administrative distance

Front 36

When redistributing OSPF, they show up on the router as O E2. What does this mean?

Back 36

OSPF external type 2

Front 37

What is the default cost when redistributing OSPF?

Back 37

20

Front 38

What is the difference between redistributing RIP and OSPF?

Back 38

OSPF is more sophisticated than RIP and can tell which routes are internal and external.

Front 39

If routes are redistributed into OSPF as type 2, What happens?

Back 39

Every router in the OSPF domain will have the same cost to reach the external networks.

Front 40

If routes are redistributed into OSPF as type 1, What happens?

Back 40

The cost to reach the external networks could vary from router to router

Front 41

To redistribute EIGRP into RIP what must we specify?

Back 41

We have to specify the AS number for EIGRP and the metric (hop count)

Front 42

The administrative distance is only __________ and can be different for each router?

Back 42

Local

Front 43

The administrative distance can or cannot be modified

Back 43

Administrative distance can be modified

Front 44

If you set and administrative distance in EIGRP to 255 what happens?

Back 44

It is labeled as unknown and will not show up in the routing table

Front 45

In OSPF what kind of administrative distances can you change?

Back 45

• External
• Inter-Area
• intra-area

Front 46

Why would we change the administrative distance?

Back 46

It can help us solve redistribution problems

Front 47

Sub-Optimal Routing

Back 47

This is when the routing protocol chooses a path that is not the quickest or most direct.

NOTE:

This is more likely to happen when redistribution is involved

Front 48

O E1

Back 48

OSPF External type 1

• Default Metric of 20
• Add Metrics at each hop

NOTE:

This makes them easier to manipulate along with internal routing paths

Front 49

When creating a route map, if you do not add a sequence number than what will happen to the networks that match the prefix-list?

Back 49

The only the networks that match the prefix list will be redistributed.

Front 50

What are the two ways you can resolve sub-optimal routing?

Back 50

• Change Matrix
• Change Administrative Distance

Front 51

What is the rule of thumb with redistribution?

Back 51

Never redistribute routing information back into the routing protocol where it originates from

Front 52

How can you tag a route?

Back 52

With the route-map command

Example

Router(config-router)#redistribute ospf 1 metric 5 route-map TAG

Front 53

Do you have to use tags with all redistributions?

Back 53

No, Only with multipoint redistribution