Lab 10: Confi guring Basic Border Gateway Protocol

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1 Lab 10: Objective Confi gure P1R1 for basic Exterior Border Gateway Protocol (EBGP). Confi gure P1R1 and P1R2 for Interior Border Gateway Protocol (IBGP). Confi rm BGP connectivity. Lab Topology For this lab, your network design will include two pods of devices. Pod 2 will be confi gured upon the initial loading of the lab. You will be responsible for confi guring Pod 1. The Pod 2 devices will be confi gured with the same IP addressing scheme as those in Pod 1. For all labs that require more than one pod, your pod will be represented as Pod 1, and the remote pod will be Pod 2. The Topology below represents the NetMap in the Simulator. To access each of the devices from within the Simulator, select the device name from the appropriate menu in the Simulator. For example, to access P1R1, click the erouters button and select P1R1 from the drop-down menu. Boson NetSim for CCNP Lab Manual 61

2 BGP Topology Command Summary Command router bgp autonomous_system_number neighbor ip_address remote-as asn neighbor ip_address next-hop-self network address {mask mask} show ip bgp summary show ip bgp neighbor show ip bgp clear ip bgp* Description enters router confi g mode for BGP establishes a BGP neighbor relationship defi nes the neighbor as a Next Hop Self neighbor specifi es networks to be advertised by BGP displays summary BGP neighbor status displays detailed BGP neighbor status displays BGP table resets all BGP peer connections 62 Boson NetSim for CCNP Lab Manual

3 Lab Tasks Task 1: Lab Preparation Make sure there is no confi guration on P1R1 and P1R2. If any confi gurations are present, erase them and reload both routers. Confi gure P1R1 and P1R2 with the IP addresses shown in the Lab Topology diagram. Assign a clock rate of to all DCE serial interfaces. On P1R1 and P1R2, enable FastEthernet 0/0, serial 0/0, and Loopback 0. Use ping to verify connectivity. Task 2: Enable Basic EBGP BSCI LAB 10 On P1R1, enable EBGP for your AS. You will need to confi gure a neighbor statement for each pod. These examples are for Pod 1. The next-hop-self command is used to force P1R1 to advertise itself as the next hop on the shared Ethernet backbone. On P1R1, confi gure a network statement for each directly connected network. Execute the show ip bgp summary command. How many neighbors are listed? How many network entries are listed? Execute the show ip route command. Do you see any BGP routes? If so, what are the administrative distances of these routes? Try the show ip bgp neighbors command. What is the BGP state of the fi rst neighbor? Task 3: Confi gure IBGP Within Pod 1 Now, confi gure IBGP between P1R1 and P1R2. 1. On P1R2, enable BGP and confi gure a network statement for each directly connected network. 2. Confi gure P1R1 and P1R2 to be BGP neighbors. Use the show ip bgp summary command to verify. 3. Use the show ip route command on P1R2. Does a route exist to the P1R1 loopback network? 4. On P1R2, what is the next hop IP address for the routes to pod 2? 5. On P1R1, confi gure the neighbor relationship to the P1R2 router with the next-hop-self option. 6. On P1R2, execute the clear ip bgp * command. Wait a minute, and then execute the show ip bgp command. What is the next hop now? Boson NetSim for CCNP Lab Manual 63

4 Lab Solutions Task 1: Lab Preparation Sample base confi guration for Pod 1 P1R1 Confi g hostname P1R1 enable password cisco interface Loopback0 ip address interface FastEthernet0/0 ip address interface Serial0/0 ip address no fair-queue clock rate interface Serial0/1 no ip address shutdown P1R2 Confi g hostname P1R2 enable password cisco interface Loopback0 ip address interface FastEthernet0/0 ip address speed auto interface Serial0/0 ip address Boson NetSim for CCNP Lab Manual

5 Task 2: Enable Basic EBGP 1. P1R1(confi g)#router bgp 1 P1R1(confi g-router)#neighbor remote-as 2 P1R1(confi g-router)#neighbor next-hop-self P1R1(confi g-router)#network mask P1R1(confi g-router)#network mask P1R1(confi g-router)#network mask One neighbor is listed. One network entry is listed. P1R1#show ip bgp summary BGP router identifi er , local AS number 1 BGP table version is 6, main routing table version 6 5 network entries and 6 paths using 701 bytes of memory 2 BGP path attribute entries using 120 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 fi lter-list cache entries using 0 bytes of memory BGP activity 5/0 prefi xes, 6/0 paths, scan interval 15 secs Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd :04:56 3 Yes. The administrative distance of these routes is 20. P1R1#show ip route C C C /24 is subnetted, 1 subnets is directly connected, FastEthernet0/ /28 is subnetted, 2 subnets is directly connected, Serial0/ is directly connected, Loopback /28 is subnetted, 2 subnets B [20/0] via , 00:07:18 B [20/0] via , 00:07:18 5. Established P1R1#show ip bgp neighbors BGP neighbor is , remote AS 2, external link BGP version 4, remote router ID BGP state = Established, up for 00:09:55 Task 3: Confi gure IBGP Within Pod 1 Boson NetSim for CCNP Lab Manual 65

6 1. 2. P1R2(confi g)#router bgp 1 P1R2(confi g-router)#network mask P1R2(confi g-router)#network mask P1R2(confi g-router)#network mask P1R1(confi g)#router bgp 1 P1R1(confi g-router)#neighbor remote-as 1 P1R2(confi g)#router bgp 1 P1R2(confi g-router)#neighbor remote-as 1 P1R1#show ip bgp summary Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd :32: :01: Yes P1R2#sh ip route /24 is subnetted, 1 subnets B [200/0] via , 00:16: /28 is subnetted, 4 subnets C is directly connected, Serial0/0 C is directly connected, FastEthernet0/0 B [200/0] via , 00:16:06 C is directly connected, Loopback /28 is subnetted, 2 subnets B [200/0] via , 00:15:56 B [200/0] via , 00:15: The next hop is P1R1(confi g-router)#neighbor next-hop-self The next hop changes to Boson NetSim for CCNP Lab Manual

7 Sample BGP Confi guration Scripts Pod 1 Router 1 Pod 1 Router 2 hostname P1R1 enable password cisco interface Loopback0 ip address interface FastEthernet0/0 ip address interface Serial0/0 ip address clock rate router bgp 1 no synchronization bgp log-neighbor-changes network mask network mask network mask neighbor remote-as 2 neighbor next-hop-self neighbor remote-as 1 neighbor next-hop-self BSCI LAB 10 hostname P1R2 enable password cisco interface Loopback0 ip address interface FastEthernet0/0 ip address speed auto interface Serial0/0 ip address router bgp 1 no synchronization bgp log-neighbor-changes network mask network mask network mask neighbor remote-as 1 Boson NetSim for CCNP Lab Manual 67

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