Lab 10: Confi guring Basic Border Gateway Protocol
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 load-ing of the lab. You will be responsible for confi gurload-ing 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 Simu-lator, 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.
BSCI LAB 10
Confi guring Basic Border Gateway Protocol
BGP Topology
Command Summary
Command
Description
router bgp autonomous_system_number enters router confi g mode for BGP neighbor ip_address remote-as asn establishes a BGP neighbor relationship
neighbor ip_address next-hop-self defi nes the neighbor as a Next Hop Self neighbor network address {mask mask} specifi es networks to be advertised by BGP show ip bgp summary displays summary BGP neighbor status show ip bgp neighbor displays detailed BGP neighbor status
show ip bgp displays BGP table
clear ip bgp* resets all BGP peer connections
Confi guring Basic Border Gateway Protocol
BSCI LAB 10
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 64000 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
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?
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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.
On P1R2, enable BGP and confi gure a network statement for each directly connected network. Confi gure P1R1 and P1R2 to be BGP neighbors. Use the show ip bgp summary command to verify. Use the show ip route command on P1R2. Does a route exist to the P1R1 loopback network? ______________________________________________________________ On P1R2, what is the next hop IP address for the routes to pod 2?
______________________________________________________________ On P1R1, confi gure the neighbor relationship to the P1R2 router with the next-hop-self option. 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?
______________________________________________________________ 1. 2. 3. 4. 5. 1. 2. 3. 4. 5. 1. 2. 3. 4. 5. 6.
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 192.168.1.1 255.255.255.240 ! interface FastEthernet0/0 ip address 10.100.100.1 255.255.255.0 ! interface Serial0/0 ip address 192.168.1.33 255.255.255.240 no fair-queue clock rate 64000 ! interface Serial0/1 no ip address shutdown ! P1R2 Confi g ! hostname P1R2 !
enable password cisco ! interface Loopback0 ip address 192.168.1.17 255.255.255.240 ! interface FastEthernet0/0 ip address 192.168.1.49 255.255.255.240 speed auto ! interface Serial0/0 ip address 192.168.1.34 255.255.255.240 !
BSCI LAB 10
Task 2: Enable Basic EBGP
P1R1(confi g)#router bgp 1
P1R1(confi g-router)#neighbor 10.100.100.2 remote-as 2 P1R1(confi g-router)#neighbor 10.100.100.2 next-hop-self
P1R1(confi g-router)#network 10.100.100.0 mask 255.255.255.0 P1R1(confi g-router)#network 192.168.1.0 mask 255.255.255.240 P1R1(confi g-router)#network 192.168.1.32 mask 255.255.255.240 One neighbor is listed.
One network entry is listed. P1R1#show ip bgp summary
BGP router identifi er 192.168.1.1, 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 10.100.100.2 4 2 8 8 6 0 0 00:04:56 3 Yes. The administrative distance of these routes is 20.
P1R1#show ip route
10.0.0.0/24 is subnetted, 1 subnets
C 10.100.100.0 is directly connected, FastEthernet0/0 192.168.1.0/28 is subnetted, 2 subnets
C 192.168.1.32 is directly connected, Serial0/0 C 192.168.1.0 is directly connected, Loopback0 192.168.2.0/28 is subnetted, 2 subnets
B 192.168.2.32 [20/0] via 10.100.100.2, 00:07:18 B 192.168.2.0 [20/0] via 10.100.100.2, 00:07:18 Established
P1R1#show ip bgp neighbors
BGP neighbor is 10.100.100.2, remote AS 2, external link BGP version 4, remote router ID 192.168.2.1
BGP state = Established, up for 00:09:55
Task 3: Confi gure IBGP Within Pod 1 1.
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P1R2(confi g)#router bgp 1
P1R2(confi g-router)#network 192.168.1.16 mask 255.255.255.240 P1R2(confi g-router)#network 192.168.1.32 mask 255.255.255.240 P1R2(confi g-router)#network 192.168.1.48 mask 255.255.255.240 P1R1(confi g)#router bgp 1
P1R1(confi g-router)#neighbor 192.168.1.34 remote-as 1 P1R2(confi g)#router bgp 1
P1R2(confi g-router)#neighbor 192.168.1.33 remote-as 1 P1R1#show ip bgp summary
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd 10.100.100.2 4 2 36 36 6 0 0 00:32:20 3 192.168.1.34 4 1 6 6 6 0 0 00:01:08 3 Yes P1R2#sh ip route 10.0.0.0/24 is subnetted, 1 subnets B 10.100.100.0 [200/0] via 192.168.1.33, 00:16:06 192.168.1.0/28 is subnetted, 4 subnets
C 192.168.1.32 is directly connected, Serial0/0 C 192.168.1.48 is directly connected, FastEthernet0/0 B 192.168.1.0 [200/0] via 192.168.1.33, 00:16:06 C 192.168.1.16 is directly connected, Loopback0 192.168.2.0/28 is subnetted, 2 subnets
B 192.168.2.32 [200/0] via 10.100.100.2, 00:15:56 B 192.168.2.0 [200/0] via 10.100.100.2, 00:15:57 The next hop is 10.100.100.2.
P1R1(confi g-router)#neighbor 192.168.1.34 next-hop-self The next hop changes to 192.168.1.33.
1. 2. 3. 4. 5. 6.
Confi guring Basic Border Gateway Protocol
BSCI LAB 10
Sample BGP Confi guration Scripts
Pod 1 Router 1 Pod 1 Router 2
hostname P1R1 !
enable password cisco ! interface Loopback0 ip address 192.168.1.1 255.255.255.240 ! interface FastEthernet0/0 ip address 10.100.100.1 255.255.255.0 ! interface Serial0/0 ip address 192.168.1.33 255.255.255.240 clock rate 64000 ! router bgp 1 no synchronization bgp log-neighbor-changes network 10.100.100.0 mask 255.255.255.0 network 192.168.1.0 mask 255.255.255.240 network 192.168.1.32 mask 255.255.255.240 neighbor 10.100.100.2 remote-as 2 neighbor 10.100.100.2 next-hop-self neighbor 192.168.1.34 remote-as 1 neighbor 192.168.1.34 next-hop-self ! hostname P1R2 !
enable password cisco ! interface Loopback0 ip address 192.168.1.17 255.255.255.240 ! interface FastEthernet0/0 ip address 192.168.1.49 255.255.255.240 speed auto ! interface Serial0/0 ip address 192.168.1.34 255.255.255.240 ! router bgp 1 no synchronization bgp log-neighbor-changes network 192.168.1.16 mask 255.255.255.240 network 192.168.1.32 mask 255.255.255.240 network 192.168.1.48 mask 255.255.255.240 neighbor 192.168.1.33 remote-as 1 !
