One of the benefits of using VIRL is the auto-configuration generation function. I assume we are all familiar with the basics of BGP syntax; I will not spend too much time on it. Following are short descriptions that will help us in understanding the scenario.
spine-1 and leaf-1 are EBGP peers; spine-1 in ASN1 while leaf-1 in ASN2:
spine-1#sh ip bgp summary
BGP router identifier 192.168.0.1, local AS number 1
...
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
10.0.128.2 4 2 262 264 30 0 0 03:54:18 2
The link between spine-1 and leaf-1 is in 10.0.128.0/17, while the server rack behind leaf-1 is in the 10.0.0.0/17 network. Spine-'s loopback IP is 192.168.0.1/32 and -1's loopback IP is 192.168.0.5/32. The most important point is that we can use 192.168.0.1 192.168.0.5 to test reachability between our new OpenFlow rack and the two routers. Ultimately, our new OpenFlow rack and Mininet host need to be able to ping the host in 10.0.0.0/17 range, specifically gateway IP 10.0.0.1 on leaf-1 and IP 10.0.0.2 on the server:
spine-1#sh ip route bgp
...
10.0.0.0/8 is variably subnetted, 4 subnets, 3 masks
B 10.0.0.0/17 [20/0] via 10.0.128.2, 03:56:53
B 10.20.1.0/24 [200/0] via 172.16.1.174, 01:35:14
192.168.0.0/32 is subnetted, 2 subnets
B 192.168.0.5 [20/0] via 10.0.128.2, 03:56:53
Before we move forward with any Ryu and Mininet connections, we should always test reachability first. A simple ping sourcing from spine-1 loopback toward the loopback of leaf-1 and server should be sufficient:
spine-1#ping ip 192.168.0.5 source 192.168.0.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.5, timeout is 2 seconds:
Packet sent with a source address of 192.168.0.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 2/6/13 ms
spine-1#
spine-1#ping ip 10.0.0.2 source 192.168.0.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.0.0.2, timeout is 2 seconds:
Packet sent with a source address of 192.168.0.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 3/4/9 ms
The last step would be to check the IP address that we received from DHCP in VMNet2 and VMnet3. For production, these will obviously be static, but in our lab, I left it as DHCP IP. In the following output, we can see that the Ryu BGP speaker should communicate to 172.16.2.51, while the Mininet switch would have an upstream neighbor of 172.16.1.250:
spine-1#sh ip int brief
Interface IP-Address OK? Method Status Protocol
GigabitEthernet0/0 10.255.0.68 YES NVRAM up up
GigabitEthernet0/1 10.0.128.1 YES NVRAM up up
GigabitEthernet0/2 172.16.2.51 YES manual up up
GigabitEthernet0/3 172.16.1.250 YES NVRAM up up
Loopback0 192.168.0.1 YES NVRAM up up [placeholder]
Great! Let's get our Ryu BGP speaker ready!