Today we will learn how to configure BGP routing protocol to ensure auto failover of multiple links from your ISP. Let me describe the scenario first.
Platform: Mikrotik Router
Primary Link IP: 172.17.176.4/27
Secondary Link IP: 172.17.160.6/27
Usable Subnet: 172.17.161.0/30
My ASN: 65503
Remote [ISP] ASN: 203
Here is the connectivity diagram:
So, Let's start the configuration. At first we will assign the primary IP address in ether1, Secondary IP address in ether2 and my usable subnet IP address ether3 interfaces.
Primary IP address assign:
Secondary IP address assign:
My usable IP subnet:
Now we need to create filters to configure BGP. Here is how to do that.
In this case my ISP should send the default route to my router and all other routes should be discarded. Let's see how to create those filters.
A BGP attribute named "local preference" can be used to mark the primary link. Usually BGP uses the default value "local preference = 100" if we don't mention any value for this attribute.
The rule is "Higher local preference will get higher priority". So we set the value to 200 to make a link as Primary link in our configuration.
To discard all other incoming routes do the following.
Do the same thing for Secondary link as well.
We have already finished the configuration of incoming filters. Now we should mention the outgoing filters as well. My ISP should receive the given IP subnet [172.17.161.0/30] from me.
We need to create outgoing filters for Primary and Secondary links as well.
Now start with BGP. Follow the steps below to configure it.
The final checking for our BGP configuration.
We are done.
Platform: Mikrotik Router
Primary Link IP: 172.17.176.4/27
Secondary Link IP: 172.17.160.6/27
Usable Subnet: 172.17.161.0/30
My ASN: 65503
Remote [ISP] ASN: 203
Here is the connectivity diagram:
So, Let's start the configuration. At first we will assign the primary IP address in ether1, Secondary IP address in ether2 and my usable subnet IP address ether3 interfaces.
Primary IP address assign:
Secondary IP address assign:
My usable IP subnet:
Now we need to create filters to configure BGP. Here is how to do that.
In this case my ISP should send the default route to my router and all other routes should be discarded. Let's see how to create those filters.
A BGP attribute named "local preference" can be used to mark the primary link. Usually BGP uses the default value "local preference = 100" if we don't mention any value for this attribute.
The rule is "Higher local preference will get higher priority". So we set the value to 200 to make a link as Primary link in our configuration.
To discard all other incoming routes do the following.
Do the same thing for Secondary link as well.
We have already finished the configuration of incoming filters. Now we should mention the outgoing filters as well. My ISP should receive the given IP subnet [172.17.161.0/30] from me.
We need to create outgoing filters for Primary and Secondary links as well.
Now start with BGP. Follow the steps below to configure it.
We are done.
