Lab
8.6.1.1 Building Peering Sessions :
IBGP vs. EBGP
Objective:
To establish a basic BGP connection
between routers and observe differences between internal and
external BGP sessions.
Before focusing on the BGP portion of
the lab, complete the following steps:
Setup the lab as shown in the
diagram.
Assign IP addresses to each
interface as shown in the diagram. The L0 address represents a
loopback address. Make sure you set up these as well.
Enable OSPF as the routing
protocol between Router A and Router B.
Advertise network 192.16.1.0 with
a wildcard mask of 0.0.255.255.
Verify you configurations are as
follows:
RTA's configuration is:
ip subnet-zero
interface Loopback0
ip address 192.16.3.1
255.255.255.0
interface Ethernet0
ip address 192.16.1.1
255.255.255.0
interface Serial1
ip address 192.16.2.1
255.255.255.0
router ospf 10
network 192.16.1.0 0.0.255.255
area 0
ip classless
RTB's configuration is:
ip subnet-zero
interface Loopback0
ip address 192.16.4.1
255.255.255.0
interface Ethernet1/1
ip address 192.16.1.2
255.255.255.0
router ospf 10
network 192.16.0.0 0.0.255.255
area 0
ip classless
RTC's configuration is:
ip subnet-zero
interface Serial1/1
ip address 192.16.2.2
255.255.255.0
ip classless
Now that we have the IGP set up, we
can configure the BGP connections:
Begin with Router A:
Enter global configuration mode.
Enable BGP on router A for AS #2.
To do this use the command:
RTA(config)#router bgp 2 RTA(config-router)#
Since AS #2 is a small Autonomous
system that is fully meshed and is not a transit AS, it is safe
to turn off the synchronization feature of BGP. To do this issue
the command:
RTA(config-router)#no synchronization
Next we must define the BGP
neighbor relationships. Router A has 2 BGP neighbors, namely
Router B and C. To define these relationships issue the
following commands:
update-sourceLoopback 0
statement.
This command specifies the interface to be used as the source ip
address of the BGP session with the neighbor.
Lastly, we are not going to
summarize routes in this lab. So we will turn off the BGP
automatic summarization at the major net boundary. To do this
issue the following command:
RTA(config-router)#no auto-summary
Save your configuration and move
to Router B.
Configuring Router B:
Before enabling BGP on this
router, issue the following command:
RTB#debug ip bgp
This command will allow you to see
the negotiation between BGP neighbors.
Enable BGP on router B for AS #2.
What command will you need to do
this? (HINT: See step 1 from Router A)
Define the BGP neighbor
relationships for router B.
What command(s) should you use to
do this?
Shut down your Ethernet interface
and then bring it back up again. You should now see the neighbor
negotiation process on your screen.
List the steps of the negotiation
process:
Issue the
show
ip bgpneighbor
command.
What kind of BGP connection is
this, internal or external?
How do you know what kind it is?
Save your configuration and move
to router C.
Configuring Router C:
Enable bgp routing on Router C for
AS #1.
What command will you need to do
this?
Define the BGP neighbor
relationships for router C.
What command will you use to do
this?
Issue the
show
ip bgp neighbor
command.
What kind of BGP connection is this,
internal or external?