BGP Load balancing ebgp-multihop
Today I am going to talk about the BGP configuration where i will tell you about the load balancing between the two links connecting two service providers via BGP protocol. We have two different methods to achieve this one is use of ebgp multihop command or the other way is to use the ttl security command and both these methods are applicable on the BGP neighbor command.
In this article, We are going to take through the ebgp multihop command on to the neighbours between two service providers. I knew many of you already knew the load balancing concept in the BGP.
In my example, I am taking two serial links between two routers which shares the e-BGP information between them which means each router belongs to the specific AS number. Below is the topology for your reference.
In the above topology, Router A is in AS100 have two serial links connected to Router B which is in AS 200 and for both the links, e-bgp is sharing information.
Below is the configuration on Router A and Router B for your reference. All the IPs and the topology uses here has no relevance with any of the live or the enterprise network and is used only for the demo purposes here.
In this article, We are going to take through the ebgp multihop command on to the neighbours between two service providers. I knew many of you already knew the load balancing concept in the BGP.
In my example, I am taking two serial links between two routers which shares the e-BGP information between them which means each router belongs to the specific AS number. Below is the topology for your reference.
 |
| Fig 1.1- use of ebgp multihop |
Below is the configuration on Router A and Router B for your reference. All the IPs and the topology uses here has no relevance with any of the live or the enterprise network and is used only for the demo purposes here.
Configurations on Router A
!
interface loopback 0
ip address 150.10.1.1 255.255.255.0
!
router bgp 100
neighbor 160.10.1.1 remote-as 200
neighbor 160.10.1.1 ebgp-multihop >>>>> Command used for using both links.
neighbor 160.10.1.1 update-source loopback 0
network 150.10.0.0
!
!
ip route 160.10.0.0 255.255.0.0 1.1.1.2
ip route 160.10.0.0 255.255.0.0 2.2.2.2
!
Hope you understand the configuration on Router A, where i defined the loopback interface with the IP address then configuring eBGP which ebgp multihop command which means that bgp will exchange information between two router via both the links shown above in the topology.
Configurations on Router B
!
interface loopback 0
ip address 160.10.1.1 255.255.255.0
!
router bgp 200
neighbor 150.10.1.1 remote-as 100
neighbor 150.10.1.1 ebgp-multihop >>>>>>> Command used for using both links.
neighbor 150.10.1.1 update-source loopback 0
network 160.10.0.0
!
ip route 150.10.0.0 255.255.0.0 1.1.1.1
ip route 150.10.0.0 255.255.0.0 2.2.2.1
!
Let me talk about something more, the neighbor ebgp-multihop and neighbor update-source router configuration commands have the effect of making the loopback interface the next hop for EBGP, which allows load balancing to occur. Static routes are used to introduce two equal-cost paths to the destination ould also be accomplished by using an IGP. Router A can reach the next hop of 160.10.1.1 in two ways: via 1.1.1.2 and via 2.2.2.2. Likewise, Router B can reach the next hop of 150.10.1.1 in two ways: via 1.1.1.1 and via 2.2.2.1.
