3.6.1.3 Lab – Configure a Branch Connection Answers

3.6.1.3 Lab – Configure a Branch Connection (Instructor Version)

Instructor Note: Red font color or gray highlights indicate text that appears in the instructor copy only.

Topology

Addressing Table

Objectives

Part 1: Build the Network and Load Device Configurations
Part 2: Configure a PPPoE Client Connection
Part 3: Configure a GRE Tunnel
Part 4: Configure BGP over PPPoE and BGP over a GRE Tunnel

Background / Scenario

In this lab, you will configure two separate WAN connections, a BGP route over a PPPoE connection, and a BGP route over a GRE tunnel. This lab is a test case scenario and does not represent a realistic BGP implementation.

Note: The routers used with CCNA hands-on labs are Cisco 1941 Integrated Services Routers (ISRs) with Cisco IOS, Release 15.2(4)M3 (universalk9 image). Other routers and Cisco IOS versions can be used. Depending on the model and Cisco IOS version, the commands available and output produced might vary from what is shown in the labs. Refer to the Router Interface Summary Table at the end of this lab for the correct interface identifiers.

Note: Ensure that the routers have been erased and have no startup configurations. If you are unsure, contact your instructor.

Instructor Note: Refer to the Instructor Lab Manual for the procedures to initialize and reload devices.

Required Resources

• 3 Routers (Cisco 1941 with Cisco IOS Release 15.2(4)M3 universal image or comparable)
• 3 Switches (Cisco 2960 with Cisco IOS Release 15.0(2) lanbasek9 image or comparable)
• Console cables to configure the Cisco IOS devices via the console ports
• Ethernet cables and Serial cables as shown in the topology

Part 1: Build the Network and Load Device Configurations

Step 1: Cable the network as shown in the topology.

Step 2: Load router configurations.

Copy and paste the following configurations into the appropriate routers and switch.

Cust 1 (R1) Configuration: 

conf t  
hostname Cust1  
no cdp run   
interface Loopback1  
 ip address 209.165.200.49 255.255.255.240  
interface GigabitEthernet0/0  
 ip address 192.168.1.1 255.255.255.0  
 no shut  
interface Serial0/0/0  
 ip address 209.165.200.81 255.255.255.252  
 no shut  
ip route 0.0.0.0 0.0.0.0 s0/0/0 25  
end

Note: In the Cust1 configuration above, CDP is disabled with the no cdp run command. The static default route with an administrative distance is manually configured to 25 instead of the default 1. The significance of these configurations will be explained later in the lab.

ISP (R2) Configuration: 

conf t  
hostname ISP  
username Cust1 password 0 ciscopppoe  
bba-group pppoe global  
 virtual-template 1  
interface Loopback 1  
 ip address 209.165.200.65 255.255.255.240  
interface GigabitEthernet0/0  
 ip tcp adjust-mss 1452  
 pppoe enable group global  
 no shut  
interface Serial0/0/0  
 ip address 209.165.200.82 255.255.255.252  
 no shut  
interface Serial0/0/1  
 ip address 209.165.200.85 255.255.255.252  
 no shut  
interface Virtual-Template1  
 mtu 1492  
 ip address 209.165.200.30 255.255.255.224  
 peer default ip address pool PPPoEPOOL  
 ppp authentication chap callin  
router bgp 65001  
 network 0.0.0.0  
 neighbor 209.165.200.1 remote-as 65000  
ip local pool PPPoEPOOL 209.165.200.1 209.165.200.20  
ip route 0.0.0.0 0.0.0.0 Loopback1  
end

Branch1 (R3) Configuration: 

conf t  
hostname Branch1  
interface GigabitEthernet0/1  
 ip address 192.168.3.1 255.255.255.0  
 no shut  
interface Serial0/0/1  
 ip address 209.165.200.86 255.255.255.252  
 no shut  
ip route 0.0.0.0 0.0.0.0 Serial0/0/1  
end

S1 Configuration: 

conf t  
hostname S1  
vlan 111  
interface f0/6  
 switchport mode access  
 switchport access vlan 111  
end

Note: Because S1 connects to two separate networks, G0/0 and G0/1 on Cust1, it is necessary to segment the switch into two separate VLANs, in this case VLAN111, and VLAN1.

Step 3: Save the configuration on all configured routers and switches.

Part 2: Configure a PPPoE Client Connection

In Part 2, following the PPPoE requirements listed below, you will configure Cust1 as the PPPoE client. The ISP router configuration is already complete.

PPPoE requirements for the Cust1 router:

– Configure an interface Dialer1 with the following settings:

• a negotiated ip address
• mtu 1492
• ppp encapsulation
• dialer pool 1
• ppp chap callin authentication
• ppp chap hostname Cust1
• ppp chap password ciscopppoe (unencrypted)

– Configure G0/1 with the following settings:

• enable global pppoe
• adjust the TCP maximum segment size to 1452
• set the pppoe-client to dialer pool 1

List the commands used to configure Cust1 as the PPPoE Client:
_______________________________________________________

Cust1(config)# interface GigabitEthernet0/1
Cust1(config-if)# ip tcp adjust-mss 1452
Cust1(config-if)# pppoe enable group global
Cust1(config-if)# pppoe-client dial-pool-number 1
Cust1(config-if)# no shut
Cust1(config-if)# interface Dialer1
Cust1(config-if)# mtu 1492
Cust1(config-if)# ip address negotiated
Cust1(config-if)# encapsulation ppp
Cust1(config-if)# dialer pool 1
Cust1(config-if)# ppp authentication chap callin
Cust1(config-if)# ppp chap hostname Cust1
Cust1(config-if)# ppp chap password ciscopppoe

If the Cust1 router is configured correctly, it should receive an IP address from the ISP router. What IP address did Cust1 receive and on what interface? What command did you use to check for the IP address and interface?
______________________________________________________
209.165.200.1 on interface Dialer1. The show command show ip interface brief or show interface dialer1

Note: If Cust1 had CDP running on interface dialer1, it could produce the following repeating log message: PPP: Outbound cdp packet dropped, NCP not negotiated. To prevent this, CDP was globally turned off.

Part 3: Configure a GRE Tunnel

In Part 3, following the GRE requirements listed below, you will configure a GRE tunnel between Cust1 and Branch1.

GRE tunnel requirements:

– On Cust1 and Branch1, configure interface Tunnel 0 with the following settings:

• IP address 192.168.2.1/24 and 192.168.2.2/24 respectively
• Tunnel mode GRE over IP
• Tunnel source interface and destination address using serial interfaces

List the commands used to configure a GRE tunnel between Cust1 and Branch1:
_________________________________________________________

Cust1(config)# interface Tunnel0
Cust1(config-if)# ip address 192.168.2.1 255.255.255.0
Cust1(config-if)# tunnel mode gre ip
Cust1(config-if)# tunnel source s0/0/0
Cust1(config-if)# tunnel dest 209.165.200.86

Branch1(config)# interface Tunnel0
Branch1(config-if)# ip address 192.168.2.2 255.255.255.0
Branch1(config-if)# tunnel mode gre ip
Branch1(config-if)# tunnel source s0/0/1
Branch1(config-if)# tunnel dest 209.165.200.81

How can you tell if the tunnel was created successfully? What command could you use to test the tunnel?
_______________________________________________________
Answers will vary, but may include the following: a console message will display when the tunnel is up, an ICMP Ping can be used to test each end of the tunnel, as well as show interface tunnel0 and show ip interface brief.

What would happen if Cust1 did not have a static default route? Test it by removing the static default route. What was the result? Make sure to replace the static default route, as shown in the Cust1 configuration in Part 1 Step2, before moving on.
_______________________________________________________
The GRE tunnel goes down without the presence of the default route. The tunnel goes back up when the static default route is replaced.

Part 4: Configure BGP over PPPoE and BGP over a GRE Tunnel

In Part 4, following the BGP requirements listed below, you will configure BGP on Cust1 and Branch1. The ISP router configuration is already complete.

BGP requirements:

– On Cust1:

• Create a BGP routing process AS 65000
• Advertise networks attached to Loopback 1 and G0/0
• Configure BGP neighbors to the ISP and Branch1 routers

– On Branch1:

• Create a BGP routing process AS 65010
• Advertise the network attached to G0/1
• Configure BGP neighbor to Cust1 only

List the commands used to configure BGP on Cust1 and Branch1:
__________________________________________________________

Cust1(config)# router bgp 65000
Cust1(config-router)# network 192.168.1.0 mask 255.255.255.0
Cust1(config-router)# network 209.165.200.48 mask 255.255.255.240
Cust1(config-router)# neighbor 192.168.2.2 remote-as 65010
Cust1(config-router)# neighbor 209.165.200.30 remote-as 65001

Branch1(config)# router bgp 65010
Branch1(config-router)# network 192.168.3.0 mask 255.255.255.0
Branch1(config-router)# neighbor 192.168.2.1 remote-as 65000

On Cust1, did you receive console messages regarding BGP neighbor relationships to ISP and Branch1?
_______________________________________________________
Yes.

On Cust1, can you ping the ISP at 209.165.200.30 over PPPoE? Can you ping the Branch1 local network at 192.168.3.1?
_______________________________________________________
Yes and yes.

Check the routing table of Cust1. What routes were learned by BGP? There should be a route learned from both ISP and Branch1.
_______________________________________________________
B* 0.0.0.0/0 [20/0] via 209.165.200.30, 19:41:23
B 192.168.3.0/24 [20/0] via 192.168.2.2, 21:30:16. 

Cust1# show ip route  
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP  
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area   
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2  
       E1 - OSPF external type 1, E2 - OSPF external type 2  
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2  
       ia - IS-IS inter area, * - candidate default, U - per-user static route  
       o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP  
       + - replicated route, % - next hop override  
  
Gateway of last resort is 209.165.200.30 to network 0.0.0.0  
  
B*    0.0.0.0/0 [20/0] via 209.165.200.30, 00:15:25  
      192.168.1.0/24 is variably subnetted, 2 subnets, 2 masks  
C        192.168.1.0/24 is directly connected, GigabitEthernet0/0  
L        192.168.1.1/32 is directly connected, GigabitEthernet0/0
      192.168.2.0/24 is variably subnetted, 2 subnets, 2 masks  
C        192.168.2.0/24 is directly connected, Tunnel0  
L        192.168.2.1/32 is directly connected, Tunnel0  
B     192.168.3.0/24 [20/0] via 192.168.2.2, 00:15:24  
      209.165.200.0/24 is variably subnetted, 6 subnets, 3 masks  
C        209.165.200.1/32 is directly connected, Dialer1  
C        209.165.200.30/32 is directly connected, Dialer1  
C        209.165.200.48/28 is directly connected, Loopback1  
L        209.165.200.49/32 is directly connected, Loopback1  
C        209.165.200.80/30 is directly connected, Serial0/0/0  
L        209.165.200.81/32 is directly connected, Serial0/0/0

Examine the two routes learned by BGP in the Cust1 routing table. What do they show about routes in the network now?
_______________________________________________________
The BGP candidate default route has an administrative distance of 20, which means it replaced the less desirable manually configured default route with an administrative distance of 25. The BGP default route is via 209.165.200.30 which means it routes over the PPPoE connection to the ISP G0/1 interface, instead of the S0/0/0 interface used by the previous manually configured default route.

The BGP route to the 192.168.3.0 network is via the Branch1 tunnel0 interface at 192.168.2.2 proving that BGP routing information is being carried across the GRE tunnel.

Router Interface Summary Table

Device Configs

Cust1 (Final)

Cust1# show run
version 15.2
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Cust1
!
boot-start-marker
boot-end-marker
!
no aaa new-model
memory-size iomem 10
!
ip cef
!
no ipv6 cef
!
multilink bundle-name authenticated
!
redundancy
!
interface Loopback1
ip address 209.165.200.49 255.255.255.240
!
interface Tunnel0
ip address 192.168.2.1 255.255.255.0
tunnel source Serial0/0/0
tunnel destination 209.165.200.86
!
interface Embedded-Service-Engine0/0
no ip address
shutdown
!
interface GigabitEthernet0/0
ip address 192.168.1.1 255.255.255.0
duplex auto
speed auto
!
interface GigabitEthernet0/1
no ip address
ip tcp adjust-mss 1452
duplex auto
speed auto
pppoe enable group global
pppoe-client dial-pool-number 1
!
interface Serial0/0/0
ip address 209.165.200.81 255.255.255.252
clock rate 2000000
!
interface Serial0/0/1
no ip address
shutdown
!
interface Dialer1
mtu 1492
ip address negotiated
encapsulation ppp
dialer pool 1
ppp authentication chap callin
ppp chap hostname Cust1
ppp chap password 0 ciscopppoe
no cdp enable
!
router bgp 65000
bgp log-neighbor-changes
network 192.168.1.0
network 209.168.200.48 mask 255.255.255.240
neighbor 192.168.2.2 remote-as 65010
neighbor 209.165.200.30 remote-as 65001
!
ip forward-protocol nd
!
no ip http server
no ip http secure-server
!
ip route 0.0.0.0 0.0.0.0 Serial0/0/0 25
!
no cdp run
!
control-plane
!
line con 0
line aux 0
line 2
no activation-character
no exec
transport preferred none
transport input all
transport output pad telnet rlogin lapb-ta mop udptn v120 ssh
stopbits 1
line vty 0 4
login
transport input all
!
scheduler allocate 20000 1000
!
end

ISP (Final)

ISP# show run
version 15.2
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname ISP
!
boot-start-marker
boot-end-marker
!
no aaa new-model
!
ip cef
!
no ipv6 cef
multilink bundle-name authenticated
!
username Cust1 password 0 ciscopppoe
!
bba-group pppoe global
virtual-template 1
!
interface Loopback1
ip address 209.165.200.65 255.255.255.240
!
interface Embedded-Service-Engine0/0
no ip address
shutdown
!
interface GigabitEthernet0/0
no ip address
ip tcp adjust-mss 1452
duplex auto
speed auto
pppoe enable group global
!
interface GigabitEthernet0/1
no ip address
shutdown
duplex auto
speed auto
!
interface Serial0/0/0
ip address 209.165.200.82 255.255.255.252
!
interface Serial0/0/1
ip address 209.165.200.85 255.255.255.252
clock rate 2000000
!
interface Virtual-Template1
mtu 1492
ip address 209.165.200.30 255.255.255.224
peer default ip address pool PPPoEPOOL
ppp authentication chap callin
!
router bgp 65001
bgp log-neighbor-changes
network 0.0.0.0
neighbor 209.165.200.1 remote-as 65000
!
ip local pool PPPoEPOOL 209.165.200.1 209.165.200.20
ip forward-protocol nd
!
no ip http server
no ip http secure-server
!
ip route 0.0.0.0 0.0.0.0 Loopback1
!
control-plane
!
line con 0
line aux 0
line 2
no activation-character
no exec
transport preferred none
transport input all
transport output pad telnet rlogin lapb-ta mop udptn v120 ssh
stopbits 1
line vty 0 4
login
transport input all
!
scheduler allocate 20000 1000
!
end

Branch1 (Final)

Branch1# show run
version 15.2
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Branch1
!
boot-start-marker
boot-end-marker
!
no aaa new-model
memory-size iomem 10
!
ip cef
!
no ipv6 cef
multilink bundle-name authenticated
!
interface Tunnel0
ip address 192.168.2.2 255.255.255.0
tunnel source Serial0/0/1
tunnel destination 209.165.200.81
!
interface Embedded-Service-Engine0/0
no ip address
shutdown
!
interface GigabitEthernet0/0
no ip address
shutdown
duplex auto
speed auto
!
interface GigabitEthernet0/1
ip address 192.168.3.1 255.255.255.0
duplex auto
speed auto
!
interface Serial0/0/0
no ip address
shutdown
clock rate 2000000
!
interface Serial0/0/1
ip address 209.165.200.86 255.255.255.252
!
router bgp 65010
bgp log-neighbor-changes
network 192.168.3.0
neighbor 192.168.2.1 remote-as 65000
!
ip forward-protocol nd
!
no ip http server
no ip http secure-server
!
ip route 0.0.0.0 0.0.0.0 Serial0/0/1
!
control-plane
!
line con 0
line aux 0
line 2
no activation-character
no exec
transport preferred none
transport input all
transport output pad telnet rlogin lapb-ta mop udptn v120 ssh
stopbits 1
line vty 0 4
login
transport input all
!
scheduler allocate 20000 1000
!
end