3.5.3.5 Lab – Configure and Verify eBGP (Instructor Version)
Instructor Note: Red font color or gray highlights indicate text that appears in the instructor copy only.
Topology
Addressing Table
| Device | Interface | IP Address | Subnet Mask |
|---|---|---|---|
| R1 | S0/0/0 (DCE) | 198.133.219.1 | 255.255.255.248 |
| R2 | S0/0/0 | 198.133.219.2 | 255.255.255.248 |
| S0/0/1 (DCE) | 209.165.200.2 | 255.255.255.252 | |
| ISP-1 | S0/0/1 | 209.165.200.1 | 255.255.255.252 |
| Web Server | 10.10.10.10 | 255.255.255.255 |
Objectives
- Part 1: Build the Network and Configure Basic Device Settings
- Part 2: Configure eBGP on R1
- Part 3: Verify eBGP Configuration
Background / Scenario
In this lab you will configure eBGP for the Company. The ISP will provide the default route to the Internet. Once configuration is complete you will use various show commands to verify that the eBGP configuration is working as expected.
Required Resources
- 3 Routers (Cisco 1941 with Cisco IOS Release 15.2(4)M3 universal image or comparable)
- Console cables to configure the Cisco IOS devices via the console ports
- Serial cables as shown in the topology
Part 1: Build the Network and Configure Basic Device Settings
In Part 1, you will set up the network topology and configure basic settings on R1 and R2 routers. You will also copy the provided configuration for ISP-1 on to that router.
Step 1: Cable the network as shown in the topology.
Step 2: Initialize and reload the network devices as necessary.
Step 3: Configure basic settings on R1 and R2.
a. Disable DNS lookup to prevent the routers from attempting to translate incorrectly entered commands as though they were host names.
b. Configure the hostnames according to the topology.
c. Configure interfaces according to the Addressing Table.
d. Save the running configuration to the startup configuration file.
Step 4: Copy configuration to ISP-1.
Copy and paste the following configuration to ISP-1.
hostname ISP-1 no ip domain-lookup interface Loopback0 ip address 10.10.10.10 255.255.255.255 interface Serial0/0/1 ip address 209.165.200.1 255.255.255.252 no shut ip route 0.0.0.0 0.0.0.0 lo0 router bgp 65001 bgp log-neighbor-changes network 0.0.0.0 neighbor 209.165.200.2 remote-as 65000 end
Part 2: Configure eBGP on R2
Configure R2 to become an eBGP peer with ISP-1. Refer to the Topology for BGP AS number information.
Step 1: Enable BGP and identify the AS number for the Company.
R2(config)# router bgp 65000
Step 2: Use the neighbor command to identify ISP-1 as the BGP peer.
R2(config-router)# neighbor 209.165.200.1 remote-as 65001
Step 3: Add the Company’s network to the BGP table so it is advertised to ISP-1.
R2(config-router)# network 198.133.219.0 mask 255.255.255.248
Part 3: Verify eBGP Configuration
In Part 3, use the BGP verifications commands to verify that the BGP configuration is working as expected.
Step 1: Display the IPv4 routing table on R2.
R2# 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
a - application route
+ - replicated route, % - next hop override
Gateway of last resort is 209.165.200.1 to network 0.0.0.0
B* 0.0.0.0/0 [20/0] via 209.165.200.1, 00:00:07
198.133.219.0/24 is variably subnetted, 2 subnets, 2 masks
C 198.133.219.0/29 is directly connected, Serial0/0/0
L 198.133.219.2/32 is directly connected, Serial0/0/0
209.165.200.0/24 is variably subnetted, 2 subnets, 2 masks
C 209.165.200.0/30 is directly connected, Serial0/0/1
L 209.165.200.2/32 is directly connected, Serial0/0/1
Step 2: Display the BGP table on R2.
R2# show ip bgp
BGP table version is 4, local router ID is 209.165.200.2
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found
Network Next Hop Metric LocPrf Weight Path
*> 0.0.0.0 209.165.200.1 0 0 65001 i
*> 198.133.219.0/29 0.0.0.0 0 32768 i
Step 3: Display the BGP connection status on R2.
R2# show ip bgp summary BGP router identifier 209.165.200.2, local AS number 65000 BGP table version is 4, main routing table version 4 2 network entries using 288 bytes of memory 2 path entries using 160 bytes of memory 2/2 BGP path/bestpath attribute entries using 320 bytes of memory 1 BGP AS-PATH entries using 24 bytes of memory 0 BGP route-map cache entries using 0 bytes of memory 0 BGP filter-list cache entries using 0 bytes of memory BGP using 792 total bytes of memory BGP activity 2/0 prefixes, 2/0 paths, scan interval 60 secs Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd 209.165.200.1 4 65001 12 11 4 0 0 00:06:56 1
Step 4: Display the IPv4 routing table on ISP-1.
Verify that the 198.133.218.0/29 network is being advertised to the ISP-1 router.
ISP-1# 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
a - application route
+ - replicated route, % - next hop override
Gateway of last resort is 0.0.0.0 to network 0.0.0.0
S* 0.0.0.0/0 is directly connected, Loopback0
10.0.0.0/32 is subnetted, 1 subnets
C 10.10.10.10 is directly connected, Loopback0
198.133.219.0/29 is subnetted, 1 subnets
B 198.133.219.0 [20/0] via 209.165.200.2, 00:00:25
209.165.200.0/24 is variably subnetted, 2 subnets, 2 masks
C 209.165.200.0/30 is directly connected, Serial0/0/1
L 209.165.200.1/32 is directly connected, Serial0/0/1
Ping the Web Server from R1. Were the pings successful? __________________
Yes, the pings should have been successful.
Reflection
The topology used in this lab was created to demonstrate how to configure the BGP routing protocol. However, the BGP protocol would not normally be configured for a topology like this in the real world. Explain. __________________
Answers may vary. BGP is normally not needed for a Single-honed network. The ISP would provide an IP Subnet range of IP addresses for the Company to use for Internet Access and the ISP would be responsible for routing the Company traffic to R2. So, only the ISP would need to have BGP configured.
Router Interface Summary Table
| Router Interface Summary | ||||
|---|---|---|---|---|
| Router Model | Ethernet Interface #1 | Ethernet Interface #2 | Serial Interface #1 | Serial Interface #2 |
| 1800 | Fast Ethernet 0/0 (F0/0) | Fast Ethernet 0/1 (F0/1) | Serial 0/0/0 (S0/0/0) | Serial 0/0/1 (S0/0/1) |
| 1900 | Gigabit Ethernet 0/0 (G0/0) | Gigabit Ethernet 0/1 (G0/1) | Serial 0/0/0 (S0/0/0) | Serial 0/0/1 (S0/0/1) |
| 2801 | Fast Ethernet 0/0 (F0/0) | Fast Ethernet 0/1 (F0/1) | Serial 0/1/0 (S0/1/0) | Serial 0/1/1 (S0/1/1) |
| 2811 | Fast Ethernet 0/0 (F0/0) | Fast Ethernet 0/1 (F0/1) | Serial 0/0/0 (S0/0/0) | Serial 0/0/1 (S0/0/1) |
| 2900 | Gigabit Ethernet 0/0 (G0/0) | Gigabit Ethernet 0/1 (G0/1) | Serial 0/0/0 (S0/0/0) | Serial 0/0/1 (S0/0/1) |
| Note: To find out how the router is configured, look at the interfaces to identify the type of router and how many interfaces the router has. There is no way to effectively list all the combinations of configurations for each router class. This table includes identifiers for the possible combinations of Ethernet and Serial interfaces in the device. The table does not include any other type of interface, even though a specific router may contain one. An example of this might be an ISDN BRI interface. The string in parenthesis is the legal abbreviation that can be used in Cisco IOS commands to represent the interface. | ||||
Device Configs
R1# show run Building configuration... Current configuration : 1334 bytes ! version 15.4 service timestamps debug datetime msec service timestamps log datetime msec no service password-encryption ! hostname R1 ! boot-start-marker boot-end-marker ! no aaa new-model memory-size iomem 15 ! no ip domain lookup ip cef no ipv6 cef multilink bundle-name authenticated ! cts logging verbose ! redundancy ! interface Embedded-Service-Engine0/0 no ip address shutdown ! interface GigabitEthernet0/0 no ip address shutdown duplex auto speed auto ! interface GigabitEthernet0/1 no ip address shutdown duplex auto speed auto ! interface Serial0/0/0 ip address 198.133.219.1 255.255.255.248 clock rate 2000000 ! interface Serial0/0/1 no ip address shutdown ! ip forward-protocol nd ! no ip http server no ip http secure-server ! control-plane ! line con 0 line aux 0 line 2 no activation-character no exec transport preferred none transport output pad telnet rlogin lapb-ta mop udptn v120 ssh stopbits 1 line vty 0 4 login transport input none ! scheduler allocate 20000 1000 ! end
R2# show run Building configuration... Current configuration : 1409 bytes ! version 15.4 service timestamps debug datetime msec service timestamps log datetime msec no service password-encryption ! hostname R2 ! boot-start-marker boot-end-marker ! no aaa new-model memory-size iomem 15 ! no ip domain lookup ip cef no ipv6 cef ! multilink bundle-name authenticated ! cts logging verbose ! redundancy ! interface Embedded-Service-Engine0/0 no ip address shutdown ! interface GigabitEthernet0/0 no ip address shutdown duplex auto speed auto ! interface GigabitEthernet0/1 no ip address shutdown duplex auto speed auto ! interface Serial0/0/0 ip address 198.133.219.2 255.255.255.248 ! interface Serial0/0/1 ip address 209.165.200.2 255.255.255.252 clock rate 2000000 ! router bgp 65000 bgp log-neighbor-changes network 198.233.219.0 mask 255.255.255.248 neighbor 209.165.200.1 remote-as 65001 ! ip forward-protocol nd ! no ip http server no ip http secure-server ! control-plane ! line con 0 line aux 0 line 2 no activation-character no exec transport preferred none transport output pad telnet rlogin lapb-ta mop udptn v120 ssh stopbits 1 line vty 0 4 login transport input none ! scheduler allocate 20000 1000 ! end
ISP-1# show run Building configuration... Current configuration : 1535 bytes ! version 15.4 service timestamps debug datetime msec service timestamps log datetime msec no service password-encryption ! hostname ISP-1 ! boot-start-marker boot-end-marker ! no aaa new-model memory-size iomem 15 ! no ip domain lookup ip cef no ipv6 cef ! multilink bundle-name authenticated ! cts logging verbose ! redundancy ! interface Loopback0 ip address 10.10.10.10 255.255.255.255 ! interface Embedded-Service-Engine0/0 no ip address shutdown ! interface GigabitEthernet0/0 no ip address shutdown duplex auto speed auto ! interface GigabitEthernet0/1 no ip address shutdown duplex auto speed auto ! interface Serial0/0/0 no ip address shutdown clock rate 2000000 ! interface Serial0/0/1 ip address 209.165.200.1 255.255.255.252 ! router bgp 65001 bgp log-neighbor-changes network 0.0.0.0 neighbor 209.165.200.2 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 Loopback0 ! control-plane ! line con 0 line aux 0 line 2 no activation-character no exec transport preferred none transport output pad telnet rlogin lapb-ta mop udptn v120 ssh stopbits 1 line vty 0 4 login transport input none ! scheduler allocate 20000 1000 ! end
