Objectives
Configure and verify eBGP between two autonomous systems.

Background / Scenario
In this activity, you will configure and verify the operation of eBGP between autonomous systems 65001 and 65002. ACME Inc. is a company that has a partnership with Other companies and must exchange routes. Both companies have their own autonomous systems and will use ISP as the transit AS to reach each other.
Note: Only companies with very large networks can afford their own autonomous system.

Address Table

Step 1: Configure eBGP in ACME Inc.

ACME Inc. hired an ISP to connect to a partner company called Other Company. The ISP has established network reachability within its network and to Other companies. You must connect ACME to the ISP so that ACME and Other companies can communicate. Because ISP is using BGP as the routing protocol, you must configure ACME1, ACME’s border router, to establish a BGP neighbor connection with ISP1, the ISP border router that faces ACME.

a. Verify that the ISP has provided IP reachability through its network by pinging 1.1.1.9, the IP address assigned to ISP2’s Serial 0/0/0.
Test connection ping from Laptop 1 to ISP-Entry2

Packet Tracer PC Command Line 1.0
C:>ping 1.1.1.9

Pinging 1.1.1.9 with 32 bytes of data:

Reply from 1.1.1.9: bytes=32 time=10ms TTL=253
Reply from 1.1.1.9: bytes=32 time=2ms TTL=253
Reply from 1.1.1.9: bytes=32 time=25ms TTL=253
Reply from 1.1.1.9: bytes=32 time=2ms TTL=253

Ping statistics for 1.1.1.9:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 2ms, Maximum = 25ms, Average = 9ms

C:>

b. From any device inside ACME’s network, ping the Other Company’s server 172.16.10.2. The pings should fail as no BGP routing is configured at this time.
Ping Other Company’s server 172.16.10.2. from Laptop1

C:>ping 172.16.10.2

Pinging 172.16.10.2 with 32 bytes of data:

Request timed out.
Reply from 172.16.10.2: bytes=32 time=4ms TTL=124
Reply from 172.16.10.2: bytes=32 time=25ms TTL=124
Reply from 172.16.10.2: bytes=32 time=13ms TTL=124

Ping statistics for 172.16.10.2:
Packets: Sent = 4, Received = 3, Lost = 1 (25% loss),
Approximate round trip times in milli-seconds:
Minimum = 4ms, Maximum = 25ms, Average = 14ms

C:>

c. Configure ACME1 to become an eBGP peer with ISP1. ACME’s AS number is 65001, while the ISP is using AS number 65003. Use the 1.1.1.1 as the neighbor IP address and make sure to add ACME’s internal network 192.168.0.0/24 to BGP.

ACME1(config)#router bgp 65001
ACME1(config-router)#neighbor 1.1.1.1 remote-as 65003
ACME1(config-router)#network 192.168.0.0 mask 255.255.255.0

From any device inside ACME’s network, ping the Other Company internal server again. Does it work?
Configure eBGP in Other Company Inc.
No, it doesn’t work this is the result

C:>ping 172.16.10.2

Pinging 172.16.10.2 with 32 bytes of data:

Reply from 192.168.0.1: Destination host unreachable.
Reply from 192.168.0.1: Destination host unreachable.
Reply from 192.168.0.1: Destination host unreachable.
Request timed out.

Ping statistics for 172.16.10.2:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),

C:>

Configure eBGP in other Company INC

The network administrator at Other Company is not familiar with BGP and could not configure their side of the link. You must also configure their end of the connection.
Configure OtherCo1 to form an eBGP adjacency with ISP2, the ISP border router facing OtherCo1. Another Company is under AS 65002 while ISP is under AS 65003. Use the 1.1.1.9 as the neighbor IP address of ISP2 and make sure to add Other Company’s internal network 172.16.10.0/24 to BGP.

OtherCo1(config)#router bgp 65002
OtherCo1(config-router)#neighbor 1.1.1.9 remote-as 65003
OtherCo1(config-router)#%BGP-5-ADJCHANGE: neighbor 1.1.1.9 Up
OtherCo1(config-router)#network 172.16.10.0 mask 255.255.255.0

Step 2: eBGP Verification

a. Verify that ACME1 has properly formed an eBGP adjacency with ISP1. The show ip bgp summary command is very useful here.
b. Use the show ip bgp summary command to verify all the routes ACME1 has learned via eBGP and their status.

ACME1(config)#do show ip bgp summary
BGP router identifier 192.168.0.1, local AS number 65001
BGP table version is 6, main routing table version 6
5 network entries using 660 bytes of memory
5 path entries using 260 bytes of memory
4/3 BGP path/bestpath attribute entries using 644 bytes of memory
2 BGP AS-PATH entries using 48 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
Bitfield cache entries: current 1 (at peak 1) using 32 bytes of memory
BGP using 1644 total bytes of memory
BGP activity 5/0 prefixes, 5/0 paths, scan interval 60 secs

Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
1.1.1.1 4 65003 21 16 6 0 0 00:14:24 4

ACME1(config)#

c. Look at the routing tables on ACME1 and OtherCo1. ACME1 should have routes learned about Other Company’s route 172.16.10.0/24. Similarly, OtherCo1 should now know about ACME’s route 192.168.0.0/24.

ACME1(config)#do 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, E – EGP
i – IS-IS, 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

Gateway of last resort is not set

 1.0.0.0/8 is variably subnetted, 4 subnets, 2 masks

C 1.1.1.0/30 is directly connected, Serial0/0/0
L 1.1.1.2/32 is directly connected, Serial0/0/0
B 1.1.1.4/30 [20/0] via 1.1.1.1, 00:00:00
B 1.1.1.8/30 [20/0] via 1.1.1.1, 00:00:00
172.16.0.0/24 is subnetted, 1 subnets
B 172.16.10.0/24 [20/26114560] via 1.1.1.1, 00:00:00
192.168.0.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.0.0/24 is directly connected, GigabitEthernet0/0
L 192.168.0.1/32 is directly connected, GigabitEthernet0/0

ACME1(config)#

d. Open a web browser in any ACME Inc. end devices and navigate to Other Company’s server by entering its IP address 172.16.10.2

e. From any ACME Inc. device, ping the Other Company’s server at 172.16.10.2.

C:>ping 172.16.10.2

Pinging 172.16.10.2 with 32 bytes of data:

Reply from 172.16.10.2: bytes=32 time=3ms TTL=124
Reply from 172.16.10.2: bytes=32 time=11ms TTL=124
Reply from 172.16.10.2: bytes=32 time=10ms TTL=124
Reply from 172.16.10.2: bytes=32 time=34ms TTL=124

Ping statistics for 172.16.10.2:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 3ms, Maximum = 34ms, Average = 14ms

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