Cisco CCIP MPLS Study Guide phần 8 pptx

When the route is ultimately learned by a downstream OSPF customer router, the route is displayed as ___________ in a customer router’s global routing table.. Internal routes, when redis

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Review Questions 311

9. External routes are redistributed into MP-BGP by a PE router When the route is ultimately learned by a downstream OSPF customer router, the route is displayed as _ in a customer router’s global routing table

A. O

B. O IA

C. O E2

D. None of the above

10. With the OSPF super-backbone, PE routers are viewed as _ routers

D. None of the above

12. Which of the following is not sent to customer OSPF routers?

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312 Chapter 7 MPLS VPNs and OSPF

13. An inter-area OSPF route is an LSA Type _

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314 Chapter 7 MPLS VPNs and OSPF

Answers to Review Questions

1. B 32 total processes are available Connected, RIPv2, and BGP all use only one process each OSPF uses a process for each individual VPN

2. A For standard OSPF, all areas must have a connection to Area 0, which is known as the backbone area

3. B Without the OSPF super-backbone, the service provider network looks like a standard BGP network Therefore, PE routers are viewed

as ASBRs

4. C The router ospf process_id vrf vpn_name command is used

to configure OSPF for a VPN

5. A Intra-area routes from with the customer’s OSPF network are displayed as O in a customer router’s routing table

6. B Standard BGP rules still apply when redistributing OSPF routes into MP-BGP The OSPF cost is carried in the BGP MED attribute

7. B Internal routes, when redistributed back into OSPF from MP-BGP, are LSA Type 3 routes and are displayed as O IA in a customer router’s global routing table

8. B Inter-area routes, when redistributed back into OSPF from MP-BGP, are LSA Type 3 routes and are displayed as O IA in a customer router’s global routing table

9. C External routes, when redistributed back into OSPF from MP-BGP, are LSA Type 5 routes and are displayed as O E2 in a customer router’s global routing table The Cisco default is O E2 for external routes

10. A With the OSPF super-backbone, PE routers are not viewed as ASBRs but as ABRs

11. B The BGP AS number is mapped to the tag field A PE router does not redistribute a route it learns if the tag field value is equal to its own

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Answers to Review Questions 315

13. B OSPF routes from one area to another are OSPF LSA Type 3

14. D OSPF routes from an external AS are OSPF LSA Type 5

15. A OSPF routes from the same area are OSPF LSA Type 1 or Type 2

16. D External routes, OSPF LSA Type 5, are flooded throughout the OSPF domain

17. B ASBR routers connect to an external AS and generate external, LSA Type 5, routes

18. A ABR routers connect to more than one OSPF area generate area, LSA Type 3, routes

inter-19. A, B Both the down bit and the tag field are used to prevent ing loops

rout-20. C When the routing bit is cleared, a route is not displayed in the global routing table, even if it is the best OSPF route

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Chapter 8

Advanced MPLS Topics

CCIP MPLS EXAM OBJECTIVES COVERED

IN THIS CHAPTER:

Identify the IOS commands and their proper syntax used

to configure advanced MPLS VPN features.

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When reviewing Cisco’s exam objectives in preparation for the exam, the “and any other relevant topics” line might get you worrying

This chapter tries to address those topics Although there are no specific exam objectives covered in this chapter, the topics discussed here may show

up on the MPLS exam

So far, you’ve learned a lot about MPLS and MPLS VPNs This chapter explains the steps required to set up MPLS VPNs using static routes and E-BGP to communicate with CE routers

In addition, you’ve learned all about simple MPLS VPN topologies This chapter introduces you to more complex MPLS VPN topologies

Static Routing

Although the exam objectives do not require you to know about static routes, I’d like you to see a working example of how static routes can be used

in a simple MPLS VPN

Figure 8.1 illustrates the simple network we’ll use in this example

F I G U R E 8 1 A simple service provider network

IGP

Serial 0/0Serial 0/0 Serial 0/1 Serial 0/0 Serial 0/1 Serial 0/0

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Static Routing 319

Figure 8.2 illustrates the routing protocol utilization of the network in Figure 8.1

F I G U R E 8 2 Routing protocol utilization

Table 8.1 lists the IP addresses and interfaces of the CE devices in Figure 8.1

Table 8.2 lists the IP addresses and interfaces of the service provider devices in Figure 8.1

T A B L E 8 1 Customer Addressing

Device Loopback 0 Serial 0

Peer 1 192.168.1.1/32 192.168.3.5/30 Peer 2 192.168.2.1/32 192.168.3.10/30

T A B L E 8 2 Service Provider Addressing

Device Loopback 0 Serial 0/0 Serial 0/1 Serial 0/3

Atlanta 204.134.83.1/32 204.134.83.5/30 192.168.3.6/30 N/A Core 204.134.83.2/32 204.134.83.9/30 204.134.83.6/30 N/A Raleigh 204.134.83.3/32 N/A 192.168.3.9/30 204.134.83.10/30

Peer 2 Peer 1 Atlanta Core Raleigh

I-BGP

AS 65000 RIPv2

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320 Chapter 8 Advanced MPLS Topics

Device Configuration

Presently, the network is set up with an IGP (RIPv2), tag switching, and MP-BGP between the Atlanta and Raleigh POP routers, as you can see in the running-config of the Raleigh POP router:

Raleigh#show running-config

Building configuration

Current configuration : 1997 bytes

!version 12.1service timestamps debug uptimeservice timestamps log uptime

no service password-encryption

!hostname Raleigh

!enable password cisco

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interface Loopback0

ip address 204.134.83.3 255.255.255.255

!interface Serial0/0

no ip address shutdown

no fair-queue clockrate 64000

!interface Serial0/1 description *** Link to Peer2 ***

ip address 192.168.3.9 255.255.255.252 clockrate 64000

no ip address shutdown clockrate 64000

!interface Serial0/3 description *** Link to Core Router ***

ip address 204.134.83.10 255.255.255.252 tag-switching ip

clockrate 64000

!interface Ethernet1/0

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interface Ethernet1/3

!router rip version 2 network 204.134.83.0 !

router bgp 65000

no synchronization bgp log-neighbor-changes neighbor 204.134.83.1 remote-as 65000 neighbor 204.134.83.1 update-source Loopback0 neighbor 204.134.83.1 next-hop-self

no auto-summary !

! address-family vpnv4 neighbor 204.134.83.1 activate neighbor 204.134.83.1 send-community both

no auto-summary exit-address-family

ip netmask-format decimalline aux 0

line vty 0 4Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com

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privilege level 15 password cisco logging synchronous login

ip netmask-format decimal

!endNotice in the running-config of the Atlanta POP router that RIPv2, tag switching, and MP-BGP are configured:

Atlanta#show running-config

Building configuration

Current configuration : 1972 bytes

!version 12.1service timestamps debug uptimeservice timestamps log uptime

!hostname Atlanta

!

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!

!interface Loopback0

ip address 204.134.83.1 255.255.255.255

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!router rip version 2 network 204.134.83.0 !

router bgp 65000

no auto-summary !

address-family vpnv4 neighbor 204.134.83.3 activate neighbor 204.134.83.3 send-community both

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line vty 0 4 privilege level 15 password cisco logging synchronous login

The first thing to configure on the Atlanta POP router is a VRF with a route distinguisher and a route target:

Atlanta#conf t

Enter configuration commands, one per line End with CNTL/Z

Atlanta(config)#ip vrf vpn_1

Atlanta(config-vrf)#rd 65000:1

Atlanta(config-vrf)#route-target both 65000:1

Next, you need to associate the interface that connects to Peer 1 with the VRF:

Atlanta(config)#int s 0/1

Atlanta(config-if)#ip vrf forwarding vpn_1

% Interface Serial0/1 IP address 192.168.3.6 removed due

to enabling VRF vpn_1Atlanta(config-if)#ip address 192.168.3.6 255.255.255.252

Now you need to configure a static route on the Atlanta POP router to point to the loopback of Peer 1 To configure a global static route, use the iproute command To configure a static route for a particular VRF, use the

iproutevrfvpn_name command The configuration on the Atlanta POP router to configure a static route associated with vpn_1 is as follows Note Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com

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that if more routes were made available from the Peer 1 router, you would need to add more static routes

Atlanta(config)#ip route vrf vpn_1 192.168.1.1 255.255.255.255 Serial0/1 192.168.3.5

For VRF static routes, the outgoing interface must be specified even if the next hop address is given.

Now on to BGP You need to configure the redistribution of the static route and VRF connected interfaces into BGP:

Atlanta(config)#router bgp 65000

Atlanta(config-router)#address-family ipv4 vrf vpn_1

Atlanta(config-router-af)#redistribute connected

Atlanta(config-router-af)#redistribute static

Atlanta(config-router-af)#^Z

Atlanta#

You need to repeat the same configuration steps on the Raleigh POP router

First, you need to configure a VRF with a route distinguisher and a route target:

Raleigh(config-vrf)#route-target both 65000:1

Next, you need to associate the interface that connects to Peer 1 with the VRF:

Now you need to configure a static route on the Atlanta POP router to point to the loopback of Peer 2 To configure a global static route, use the Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com

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ip route command To configure a static route for a particular VRF, use

the ip route vrf vpn_name command The configuration on the Raleigh

POP router to configure a static route associated with vpn_1 is as follows:

Raleigh(config)#ip route vrf vpn_1 192.168.2.1 255.255.255.255 Serial0/1 192.168.3.10

Now on to BGP You need to configure the redistribution of the static route and VRF connected interfaces into BGP:

Raleigh(config)#router bgp 65000 Raleigh(config-router)#address-family ipv4 vrf vpn_1 Raleigh(config-router-af)#redistribute connected Raleigh(config-router-af)#redistribute static Raleigh(config-router-af)#^Z

Raleigh#

The following sections contain the running-configs of the Atlanta and Raleigh POP routers Try to get in the habit of reading and verifying the configuration

!hostname Raleigh

!

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!

!memory-size iomem 25

ip cefcns event-service server

ip address 204.134.83.3 255.255.255.255

ip vrf forwarding vpn_1

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clockrate 64000

!router rip version 2 network 204.134.83.0

!router bgp 65000

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no auto-summary !

address-family ipv4 vrf vpn_1 redistribute connected

redistribute static

no auto-summary

no synchronization exit-address-family !

!

ip classless

ip route vrf vpn_1 192.168.2.1 255.255.255.255 Serial0/1 192.168.3.10

no ip http server

!

!line con 0 exec-timeout 0 0 privilege level 15 logging synchronous transport input none

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!hostname Atlanta

ip cefcns event-service server

!

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!

!interface Loopback0

ip address 204.134.83.1 255.255.255.255

ip vrf forwarding vpn_1

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!router rip version 2 network 204.134.83.0

!router bgp 65000

no auto-summary !

address-family ipv4 vrf vpn_1 redistribute connected

redistribute static

no auto-summary

no synchronization exit-address-family !

!

ip classless

ip route vrf vpn_1 192.168.1.1 255.255.255.255 Serial0/1 192.168.3.5

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!end

Peer Router Configuration

The Peer 1 and Peer 2 routers need to be configured with standard default routes The configuration of the Peer 1 router is as follows:

Peer1#conf t

Peer1(config)#ip route 0.0.0.0 0.0.0.0 serial 0

The configuration of the Peer 2 router is as follows:

Peer2#conf t

Peer2(config)#ip route 0.0.0.0 0.0.0.0 serial 0

To verify static routes on the Peer 1 router, use the show ip route command:

Peer1#show ip route

Output Omitted

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