You will have to create two alert rules one for the primary and one for the secondary path.

To create the 2nd rule just repeat the walkthrough guide and on step 3 choose the “Secondary-IPv4” Option

1.) Go to the ExpressRoute you want to monitor and click on “Metrics”

2.) Choose the “ExpressRoute Standard metrics” and “BGP Availability”

3.) Now click on “Add Filter” and choose “Peer” and “Primary-IPv4”

4.) Click on “New alert rule”

5.) Change the condition by clicking on it

6.) Now the change the values to “less than” “95%” and check if you are OK with the frequency

7.) Now select “add action group” and if you are doing the first path click on “+Create Action Group”

8.) Give it a name which matches

9.) Under “Notifications” choose “Email/SMS/Push/Voice/” and configure it like you want to have it

10.) You can skip “Actions” and click on “Create”

11.) Now insert the “Alert rule name” Change the severity like you want to have it and click on “Create alert rule”