NSX-T Configuring eBGP in Tier-0 Router - Part 16

To enable access between your VMs and the outside world, you can configure an external BGP (eBGP) connection between a tier-0 logical router and a router in your physical infrastructure.
When configuring BGP, you must configure a local Autonomous System (AS) number for the tier-0 logical router.  You must also configure the remote AS number of the physical router. The remote neighbor IP address. The neighbor must be in the same IP subnet as the uplink on the tier-0 logical router. BGP multihop is supported.

Prerequisites

• Verify that the tier-1 router is configured to advertise connected routes.  This is not strictly a prerequisite for BGP configuration, but if you have a two-tier topology and you plan to redistribute your tier-1 networks into BGP, this step is required.
• Verify that a tier-0 router is configured.
• Make sure the tier-0 logical router has learned routes from the tier-1 logical router.  

If you missed previous parts in this blogpost series. Here is the Links:-
Part - 1
Part - 2
Part - 3
Part - 4
Part - 5
Part - 6
Part - 7
Part - 8
Part - 9
Part - 10
Part - 11
Part - 12
Part - 13
Part - 14
Part - 15 
  
How to Configure eBGP

1. Login to NSX Manager UI

 2. Routing > Routers > Select Tier-0 Router > Routing  > BGP

3. Enable the Status > Save

4. Under Neighbors > Click on Add > Configure Neighbor Address  and Remote AS

5. Configure Local Address > Add

6. Now Add the Second Address of Neighbor in same way as done in above steps

7. Now configure the Route Advertisement on Tier-1 Router
Select Tier-1 Router > Routing Tab > Route Advertisement

To provide Layer 3 connectivity between VMs connected to logical switches that are attached to different tier-1 logical routers, it is necessary to enable tier-1 route advertisement towards tier-0. You do not need to configure a routing protocol or static routes between tier-1 and tier-0 logical routers. NSX-T creates NSX-T static routes automatically when you enable route advertisement.

For example, to provide connectivity to and from the VMs through other peer routers, the tier-1 logical router must have route advertisement configured for connected routes. If you don't want to advertise all connected routes, you can specify which routes to advertise.

Prerequisites

• Verify that VMs are attached to logical switches.
• Verify that downlink ports for the tier-1 logical router are configured.

8. Enable Route Advertisement > Save

9. Now configure the Route Redistribution on Tier-0 Router.
Select Tier-0 > Route Redistribution

Prerequisites

• Verify that the tier-0 and tier-1 logical routers are connected so that you can advertise the tier-1 logical router networks to redistribute them on the tier-0 logical router.
• If you want to filter specific IP addresses from route redistribution, verify that route maps are configured. 

10. Edit > Enable Route Redistribution > Save

11. Click on Add > Configure what are routes you want to redistribute > Add

Select the source route check boxes you want to redistribute.

1. Static - Tier-0 static routes.
2. NSX Connected - Tier-1 connected routes.
3. NSX Static - Tier-1 static routes. These static routes are created automatically.
4. Tier-0 NAT - Routes generated if NAT is configured on the tier-0 logical router.
5. Tier-1 NAT - Routes generated if NAT is configured on the tier-1 logical router.