INE3010 Pre Lab 2: BGP

Objective

  - Setup BGP on Cisco router and Zebra routing daemon
  - Examine the relation between BGP and IGP (interior gateway protocols)

Reference Materials

  - Using the Border Gateway Protocol for Interdomain Routing
        http://www.cisco.com/univercd/cc/td/doc/cisintwk/ics/icsbgp4.htm
  - IOS Configuring BGP
  - Zebra docs

Setup

  - equipment: Catalyst 2950 switch, Cisco 1721 router, 3 VMs (VM1, VM2 & VM5)


        .....................................................
        : AS500 150.0.0.0/16                                :
        :                                                   :
        :    +-----+.1     192.168.224.0/30    .2+-----+    :
        :    |C1721|-----------------------------| VM5 |    :
        :    +-----+                             +-----+    :
        :...... |.1 ............................. .1| ......:
                |                                   |
                |192.168.1.0/24       192.168.2.0/24|
                |                                   |
       ........ |.2 ......                 ...... .2| ........
       : AS  +-----+     :                 :     +-----+ AS  :
       : 200 | VM2 |     :                 :     | VM1 | 100 :
       :     +-----+     :                 :     +-----+     :
       :                 :                 :                 :
       : 170.0.0.0/16    :                 : 160.0.0.0/16    :
       :.................:                 :.................:

Steps

1. Setup the BGP routers on Cisco router and VMs. Advertise networks for
   the AS. You have to add a static route for the networks in the AS before
   the BGP router will advertise the networks. e.g.

     ip route 150.0.0.0 mask 255.255.255.0 null0 (for Cisco)
     ip route 160.0.0.0/16 lo (for zebra)

   For Cisco router, turn on the BGP synchronization flag

     router bgp 500
       synchronization

2. On each BGP router, examine the status of the peer routers and
   the routes advertised with the command

     show ip bgp
     show ip bgp summary
     show ip bgp neighbor

   From the ip route table, identify the routes learn from BGP.

3. Through AS500, AS100 and AS200 should be connected. Check if VM2 
   can learn the routes from AS100.

4. Synchronization: Check the reference #1 and IOS manual concerning the 
     synchronization rule and the relation between IBGP and IGPs.

   Cisco IOS have a way to override the sync rule when the transit routers
   are running BGP (just like the config in this lab). You can disable the
   sync by (which is default on IOS)

     router bgp 500
       no synchronization

   On zebra, there is no way to override the sync rule, you have to 
   redistribute the BGP routes into IGP. In our lab, enable OSPF on
   Cisco router and VM5, on Cisco router, advertise the network connected
   to VM2 (the EBGP peer) and redistribute the BGP routes 

       redistribute bgp 500 subnets
       network 192.168.1.0 0.0.0.255 area 0

   on VM5, advertise the network connected to VM1 (the EBGP peer)

       network 192.168.2.0/24 area 0

5. Check if VM2 can see the routes from AS100 and VM1 can see the routes
   from AS200.