Azure Looking Glass

I have gotten pretty close to figuring out my issue with the Azure Cloud. When I advertise my routes through one specific upstream provider, I have an issue. If I pull my routes from them, all works well. I believe this is some type of MTU issue. Could be filtering, but I doubt it. Is there an Azure Looking glass that I can use to originate pings and traceroutes? My googlefu is weak and I haven't found it yet. With that information, I think I can help my upstream provider know where the problem lies. John Acock AS395437