Ccnp Route Chapter 4

Front 1

What are the 4 most common uses for route-maps?

Back 1

* Redistribution
* Policy-based routing (PBR)
* NAT
* BGP

Front 2

What is a big difference between a route-map and an access list?

Back 2

route maps can modify the packet or route by using set commands

Front 3

What happens if a route-map statement contain several match statements?

Back 3

All match statements must be true for for the route-map statement to be considered matched. (A logical AND operation)

Front 4

What is the purpose of policy based routing?

Back 4

To let packets take a route other than the obvious shortest path.

Front 5

What should be documented in an implementation plan when planning route map configuration for PBR?

Back 5

* Define the route map, conditions to match, action when theres a match
* Which interface the route map will be attached to

Front 6

What should be documented in an implementation plan when planning route map configuration for redistribution?

Back 6

* Define the route map, conditions to match, action when theres a match
* Define where the route map will be used to control redistribution

Front 7

What is the purpose of distribute lists?

Back 7

To allow an access list to be applied to routing updates

Front 8

Where is the distribute list configured?

Back 8

Under the routing protocol process

Front 9

What factors can distribute lists filter on?

Back 9

* Incoming interface
* Outgoing interface
* Redistribution from another routing protocol

Front 10

What should be documented in an implementation plan when planning to configure distribute lists?

Back 10

* Define traffic filtering requirements that will be used to permit or deny routes, using an access list or a route map
* Define a distribute list to use the access list or route map, and wether it will be applied inbound or outbound

Front 11

What are the 3 steps to configure a distribute list?

Back 11

* Identify the network addresses of the routes to filter and create an access list
* Determine if you want to filter traffic incoming or outgoing on an interface, or routes being distributed from another protocol
* Use the distribute-list command to assign the access list to filter outgoing updates

Front 12

What are some drawbacks to using distribute lists as route filters?

Back 12

* A subnet mask cannot be easily matched
* Access lists are evaluated sequentially for every IP prefix in the routing update
* A extended access list can be cumbersome to configure

Front 13

What are some advantages of using prefix lists instead of access lists when doing route filtering?

Back 13

Significant performance improvement over access lists in loadin and route lookup of large lists.

Front 14

What are the key issues with redistribution?

Back 14

* Routing feedback (loops)
* Incompatible routing information, path selection might not be optimal
* Inconsistent convergence times

Front 15

What are the default seed metrics for these protocols?

RIP
IGRP/EIGRP
OSPF
IS-IS
BGP

Back 15

RIP 0, Infinity
IGRP/EIGRP 0, Infinity
OSPF 20, 1 for BGP, all E2 (for OSPF to OSPF the metric is preserved)
IS-IS 0, not infinity
BGP BGP metric is set to IGP value

Front 16

Multipoint one-way only works well if:

Back 16

- The receiving protocol supports different administrative distances for internal and external routes (EIGRP, OSPF, BGP)
- The AD of the receiving protocols external routers is higher than the AD of the "from"-protocols routes.

Front 17

How can you prevent loops in multipoint redistribution scenarios?

Back 17

- Insert only internal routes from protocol A to B (and vice versa)
- Tag routes in redistribution points and filter based on these tags when configuring redistribution in the other direction.
- Propagate metrics from routing protocol A to protocol B properly
- Use default routes to avoid having to do two-way redistribution

Front 18

What is the safest way of implementing redistribution?

Back 18

Only one direction on only one boundary router within the network.
(One-point one way)

Front 19

What are some common network performance issues related to routing?

Back 19

* Excessive routing updates
* Presence of any route maps/filters
* The number of routing protocols running in the same AS

Front 20

What are the solutions to common network performance issues related to routing?

Back 20

* Design changes
* Using passive interfaces
* Route filtering

Front 21

What techinques can be used to filter routes?

Back 21

* Distribute lists
* Access lists
* Route maps
* Prefix lists

Front 22

What are some reasons for running more than one routing protocol?

Back 22

* Migration
* Host system needs
* Mixed-vendor environment
* Political and geographical borders
* MPLS VPNs

Front 23

What happens to the routing table of the router performing the redistribution?

Back 23

Nothing, it doesnt change

Front 24

What are some issues arising when redistributing routes?

Back 24

* Routing loops
* Incompatible routing information
* Inconsistent convergence times

Front 25

What are the two methods of one-point route redistribution?

Back 25

one way and two way

Front 26

What is a possible issue with one-point one way and one-point two way redistribution?

Back 26

Suboptimal routing

Front 27

What are the two methods of multipoint route redistribution?

Back 27

One way and two way

Front 28

What is a key issue with multipoint redistribution?

Back 28

It is likely to introduce potential routing loops

Front 29

In which routing protocol routing process can you use the "subnets" parameter when redistributing into that protocol?

Back 29

OSPF

Front 30

How can you prevent a routers routing updates from being sent through a specific router interface?

Back 30

with the "passive-interface" router configuration command

Front 31

How can the administrative distance be manipulated to influence the route selection process?

Back 31

With the "distance" router configuration command for all protocols.

Front 32

What two commands are good to use to verify route redistribution?

Back 32

show ip route [ip address] and traceroute [ip address]

Front 33

When configuring route-maps for PBR, which command goes under the interface?

Back 33

ip policy route map [map-tag]

Front 34

What can allow an access list to be applied to routing updates?

Back 34

A distribute-list

Front 35

What methods can be used to filter routes?

Back 35

Access lists, route maps, distribute lists, prefix lists

Front 36

What may be the cause of a routing loop in a network that has redundant paths between two routing processes?

Back 36

Depending on how redistribution is deployed, routers might send routing information back into a routing protocol.

Front 37

When configuring a default metric for redistributed routes, should the metric be set to a value larger or smaller than the largest metric within the receiving autonomous system?

Back 37

Larger, to help prevent suboptimal routing and loops.

Front 38

What are some applications of route-maps?

Back 38

* Route filtering during redistribution
* PBR
* NAT
* BGP