A new feature is coming on Azure to help you gaining insight on your ExpressRoute.
With this new ExpressRoute monitoring solution you will be able to gain a comprehensive network monitoring between your branch offices, VNet and now ExpressRoute, including lost packets, bandwidth usage and network route analysis.
This monitoring feature is using the Network Performance Monitor on Azure introduced earlier this year (see https://cloudblogs.microsoft.com/hybridcloud/2017/02/22/introducing-network-performance-monitor-for-network-visibility-across-public-and-hybrid-clouds/).
To enroll to the preview go to https://aka.ms/npmcohort