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UniNets CCNP ROUTE LAB MANUAL


CCNP ROUTE – 300-101

UNiNets

CCNP Cisco Certified Network

Professional

ROUTE LAB MANUAL



CCNP TOPOLOGY



Lab: BGP Update Source Mismatch

TASK

• Configure R1's interface Ethernet0/0 with the IP address of 12.0.0.1/8

• Configure R2's interface Ethernet0/0 with the IP address of 12.0.0.2/8

• Configure R1 and R2 to be in BGP AS 1

• Configure Loopback 0 with IP 1.1.1.1/32 on R1

• Configure a BGP neighbor statement on R1 specifying R2's interface Ethernet0/0 as the

remote peer

• Configure a BGP neighbor statement on R2 specifying R1's interface loopback 0 as the

remote peer.

• Check whether R1 and R2 are able to form neighbourship or not, if Not Rectify the issue.

• Create the loopback 0 on R2 with IP 2.2.2.2/32 and form BGP neighbourship between

them.

Step1: Do the basic Connectivity on the devices to make it ready for BGP Configuration

SW1 Configuration:

Config t

vlan 12

interface Ethernet1/0

switchport access vlan 12

switchport mode access

duplex auto

!

interface Ethernet2/0

switchport access vlan 12

switchport mode access

duplex auto

===============================================

R1 Configuration:



conf t

R1(config)#int e0/0

R1(config-if)#ip address 12.0.0.1 255.0.0.0

R1(config)#int lo0


===================================================

R2 Configuration:

R2(config)#int e0/0


========================================================

Verification:

Step2: Configuration of BGP Neighbourship

R1(config)#router bgp 1

R1(config-router)#neighbor 12.0.0.2 remote-as 1



When establishing a BGP peering relationship, the source IP address used for BGP traffic by default is

based on the IP address of the outgoing interface used to reach the destination. When a BGP speaker



receives a BGP packet, it checks the configured remote-peer statements to see if a peering has been

configured

for this neighbor. If the BGP packet received has a source IP address that is different from a configured

peer, it has no way to associate the packet with the peer in question, and hence the connection is

refused. In this scenario R1 is sending BGP packets to R2 using the source IP address of 12.0.0.1 (the IP

address of the outgoing interface), while R2 is expecting a BGP peering to come from 1.1.1.1 When R1

attempts to initiate the TCP session to R2, R2 refuses it, as seen by the ACK RST packet sent from R2 to

R1.

This exercise demonstrates that the TCP server (the peer receiving the connection attempt) must agree

on what address the BGP peering will be accepted from. In the case that a mismatch occurs, the

connection will be refused.

To rectify this:

R2(config)#router eigrp 100

R2(config-router)#network 0.0.0.0 0.0.0.0

R1(config)#router eigrp 100

R1(config-router)#network 0.0.0.0 0.0.0.0


R1(config-router)#neighbor 12.0.0.2 update-source loopback 0

Step3 : Configure Loopback 0 on R2 and Establish Neighbor ship between R1 and R2 via

Loopback .

R2(config)#int lo0



R2(config-router)#neighbor 1.1.1.1 update-source loopback 0


R1(config-router)#no neighbor 12.0.0.2 remote-as 1

R1(config-router)#no neighbor 12.0.0.2 update-source Loopback0




R1(config-router)#neighbor 2.2.2.2 update-source loopback

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