Leased line & BGP & PI addresses

In this example I will deal with a BGP connection to the internet with PI address space. Firstly PI address space or Provider Independent space, is address space that is associated with you and you alone. This means that is can be advertised by more than one ISP. To do this with BGP you need an AS (Autonomous System) number as well. The example below deals with a connection to only one ISP. BGP does not come into its own until you have multiple ISP connections. Please note the route to null. Even though we are not using all the address space, it is your space so advertise it all to the Internet.

Information Needed

From You
router                                              The hostname of your router
cisco                                               The password for telneting to your router
ciscoen                                            The password for enable access to your router
AS65002                                        Your Autonomous System number

From your ISP
172.16.1.1, 172.16.1.2                   The DNS servers on your ISP’s network
172.16.1.0 255.255.255.252          This is the subnet that you use to connect on your leased line
10.0.0.0 255.255.255.0                  These are the addresses for your public servers
AS65001                                        The ISP’s Autonomous System number

Sample Configuration

service timestamps debug uptime
service timestamps log datetime msec
service password-encryption
!
hostname router
!
enable secret ciscoen
!
no aaa new-model
ip subnet-zero
!
interface FastEthernet0
description === To ISP ===
ip address 172.16.1.2 255.255.252
speed 100
full-duplex
no cdp enable
!
interface FastEthernet1
description === Your DMZ Network ===
ip address 10.0.0.1 255.255.255.224
duplex full
speed 100
no cdp enable
!
router bgp 65002
no synchronization
bgp log-neighbor-changes
network 10.0.0.0 mask 255.255.255.0
aggregate-address 10.0.0.0 255.255.255.0
neighbor 172.16.1.1 remote-as 65001
no auto-summary
!
ip classless
ip route 10.0.0.0 255.255.255.0 Null0
no ip http server
!
access-list 1 permit 10.0.0.0 0.0.0.255
no cdp advertise-v2
no cdp run
!
line con 0
line aux 0
line vty 0 4
access-class 1 in
password cisco
login
!
end

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