Basic Concepts


In a simple topology with a network of two BGP neighbors, The BGP neighbor information is specified, while the two in-band networks are used to establish TCP sessions between the two switches.


To establish a fabric communication between the two switches over the BGP network, you need to do the following:


 

Figure 10 - Example Network of Two BGP Neighbors Topology


  1. Create a vrouter in each switch.
  2. Set up BGP peering and redistribute routes so that they can reach each other’s in-band networks.
  3. Setup up global static routes using the local vrouter as the gateway. You need to do this because the routes reside inside the vrouter and each switch needs to reach the other switch’s in-band network.
  4. Enable switch-B to join the fabric that was created by switch-A.


Creating a vRouter for Fabric Communication


Use the fabric-comm-vrouter-bgpcreate command to create a vRouter for fabric communication. This command has the following options:


name: vrouter name

bgp-as: BGP As number of the vrouter

bgp-redistribute: (default connected)

bgp-max-paths: (optional)

bgp-ibgp-multipath: (optional)

interface to communicate with other router:

IP address/netmask

vlan - vlan of the interface, or

l3-port - layer 3 port to use

bgp neighbor info: (optional)

neighbor: IP address

remote-as: neighbor AS number

interface info to communicate with current switch inband: (optional)

IP address/netmask

fabric network:

network/netmask to reach inband network of the switch that created the fabric

bfd: To use BFD for rapid BGP peer loss detection

allowas-in:

Accept routes with own AS in AS_PATH

This is only required for cluster connections

 

This CLI performs the majority of the actions in Steps 1 - 4 in the above example using the information provided in the CLI. However, it does not:


  • change the inband IP address
  • create the actual fabric


If the inband network uses a /30 netmask, then it automatically determines the vrouter inband IP address from the main inband IP address. The switch that creates the fabric (the root switch) does not specify the fabric network, but does need to create a route to the other switch’s inband network.


switch-A> fabric-create name myfabric

switch-A> fabric-comm-vrouter-bgp-create name vrouter-a bgp-nic-l3-port 10 bgp-as 65001 bgpnic-

ip 192.169.0.5/30 in-band-nic-ip 12.1.1.10/24 remote-as 65002 neighbor 192.169.0.6 bgpredistribute

connected

switch-A> fabric-in-band-network-create 12.1.2.0/30

switch-B> fabric-comm-vrouter-bgp-create name vrouter-b bgp-nic-l3-port 20 bgp-as 65002 bgpnic-

ip 192.169.0.6/30 in-band-nic-ip 12.1.2.10/24 remote-as 65001 neighbor 192.169.0.5

fabric-network 12.1.1.0/24 bgp-redistribute connected

switch-B> fabric-join switch-ip 12.1.1.1

Joined fabric myfabric. Restarting nvOS...