ExaBGP and Cisco Nexus - BGP Simulation
Exabgp is one of the Simplest and opensource tool to insert BGP Routes ( IXIA Network being a Costly Affair )
Exabgp Requires two files to work
1.exabgp.conf - Setting of BGP information of Peer
2. Script that prints routes to stdout , which is picked by exabgp daemon
Script can in any language bash , python ..
Route in stdout is in format of
( learn )
announce route 100.10.10.0/24 next-hop self
( unlearn)
withdraw route 101.10.10.0/24 next-hop self"
So if you connecting it to Cisco Nexus 7000 Switches , below is simplest congfiguration to get started.
Nexus 7000 Config
n7k# show running-config
feature bgp
router bgp 100
neighbor 20.1.1.20 remote-as 2
address-family ipv4 unicast
interface Ethernet1/1
ip address 20.1.1.10/24
no shutdown
Exabgp Server
interface should be configure using ifconfig ethx 20.1.1.20 netmask 255.255.255.0
&
Exabgp.conf ( /etc/exabgp/exabgp.conf) -
neighbor 20.1.1.10 {
router-id 1.1.1.1;
local-address 20.1.1.20;
local-as 2;
peer-as 100;
family {
ipv4 unicast;
}
process myapp {
#run /usr/bin/python /etc/exabgp/iplist.py;
#run /usr/bin/python /etc/exabgp/test.py;
run /bin/bash /etc/exabgp/a.sh;
}
}
where in process myapp section there is script to generates routes to stdout which is picked by Exabgp.
sample scripts eg.
1. Python
#!/usr/bin/env python
from sys import stdout
from time import sleep
import time
import sys
i = 0
j = 0
k = 0
#learn Routes 100.10.1.0....10.10.255.0
while True:
k += 1
if k == 255:
j += 1
if j == 255:
break;
sys.stdout.write('announce route 100.%d.%d.0/24 next-hop self \n' % (j,k))
sys.stdout.flush()
#introduce delay in annoucing route
sleep(10)
#unlearn Routes 10.10.101.0...10.10.255.0
count = 100
while True:
count += 1
if count == 255:
break;
sys.stdout.write('withdraw route 100.10.%d.0/24 next-hop self \n' % (count))
sys.stdout.flush()
#introduce delay in annoucing route
#Loop endlessly to allow ExaBGP to continue running
while True:
sleep(1)
2. bash script example
#!/bin/bash
# A shell script to print each number five times.
for (( k = 1 ; k <= 200; k++ )) ### Inner for loop ###
do
#echo "announce route 100.10.$k.0/24 next-hop self"
echo "withdraw route 100.10.$k.0/24 next-hop self"
done
# done
for (( ; ; ))
do
sleep 1
done
Good Reads
https://www.m00nie.com/2014/01/bgp-rtbh-setup-using-exabgp/
http://www.trex.fi/2016/exabgp-trex.pdf
https://github.com/Exa-Networks/exabgp/wiki/Controlling-ExaBGP-:-_-README-first
http://blog.bajzelj.com/2015/12/using-exabgp-to-control-your-routers.html
