Route advertisement ​

When Microsoft peering gets configured on your ExpressRoute circuit, the Microsoft Edge routers establish a pair of Border Gateway Protocol (BGP) sessions with your edge routers through your connectivity provider.

No routes are advertised to your network. To enable route advertisements to your network, you must associate a route filter.

In order to associate a route filter:

• You must have an active ExpressRoute circuit that has Microsoft peering provisioned.
• Create an ExpressRoute circuit and have the circuit enabled by your connectivity provider before you continue. The ExpressRoute circuit must be in a provisioned and enabled state.
• Create Microsoft peering if you manage the BGP session directly. Or, have your connectivity provider provision Microsoft peering for your circuit.

Get a list of BGP community values

BGP community values associated with services accessible through Microsoft peering is available in the ExpressRoute routing requirements page.

Make a list of the values that you want to use

Make a list of BGP community values you want to use in the route filter.

Bidirectional Forwarding Detection ​

ExpressRoute supports Bidirectional Forwarding Detection (BFD) both over private and Microsoft peering.

When you enable BFD over ExpressRoute, you can speed up the link failure detection between Microsoft Enterprise edge (MSEE) devices and the routers that your ExpressRoute circuit gets configured (CE/PE). You can configure ExpressRoute over your edge routing devices or your Partner Edge routing devices (if you went with managed Layer 3 connection service).

This section walks you through the need for BFD, and how to enable BFD over ExpressRoute.

You can enable ExpressRoute circuit either by Layer 2 connections or managed Layer 3 connections. In both cases, if there are more than one Layer-2 devices in the ExpressRoute connection path, the responsibility of detecting any link failures in the path lies with the overlying BGP session.

On the MSEE devices, BGP keep-alive and hold-time are typically configured as 60 and 180 seconds, respectively. For that reason, when a link failure happens it can take up to three minutes to detect any link failure and switch traffic to alternate connection.

You can control the BGP timers by configuring a lower BGP keep-alive and hold-time on your edge peering device.

If the BGP timers are not the same between the two peering devices, the BGP session will establish using the lower time value. The BGP keep-alive can be set as low as three seconds, and the hold-time as low as 10 seconds.

In this scenario, BFD can help. BFD provides low-overhead link failure detection in a sub second time interval.

Enabling BFD ​

BFD is configured by default under all the newly created ExpressRoute private peering interfaces on the MSEEs. As such, to enable BFD, you only need to configure BFD on both your primary and secondary devices.

Configuring BFD is two-step process.

1. You configure the BFD on the interface
2. Link it to the BGP session.

When you disable a peering, the Border Gateway Protocol (BGP) session for both the primary and the secondary connection of your ExpressRoute circuit is shut down. When you enable a peering, the BGP session on both the primary and the secondary connection of your ExpressRoute circuit is restored.

Resetting your ExpressRoute Peerings might be helpful in the following scenarios:

• You are testing your disaster recovery design and implementation. For example, assume that you have two ExpressRoute circuits. You can disable the Peerings of one circuit and force your network traffic to use the other circuit.

• You want to enable Bidirectional Forwarding Detection (BFD) on Azure private peering or Microsoft peering.

Choose a peering location ​

Peering location is of importance when working with ExpressRoute.

Azure regions ​

Azure regions are global datacenters where Azure compute, networking and storage resources are located. When creating an Azure resource, a customer needs to select a resource location. The resource location determines which Azure datacenter (or availability zone) the resource is created in.

ExpressRoute locations (Peering locations) ​

ExpressRoute locations (sometimes referred to as peering locations or meet-me-locations) are co-location facilities where Microsoft Enterprise Edge (MSEE) devices are located.

ExpressRoute locations are the entry point to Microsoft's network – and are globally distributed, providing customers the opportunity to connect to Microsoft's network around the world. These locations are where ExpressRoute partners and ExpressRoute Direct customers issue cross connections to Microsoft's network. You would have access to Azure services across all regions within a geopolitical region if you connected to at least one ExpressRoute location within the geopolitical region.

Azure regions to ExpressRoute locations within a geopolitical region. ​

The following link provides a list of Azure regions to ExpressRoute locations within a geopolitical region. This page is kept up to date with the latest ExpressRoute locations and providers.

ExpressRoute connectivity providers ​

The following link list's locations by service provider. This page is kept up to date with the latest available providers by location, see Service providers by location.

Connectivity through satellite operators ​

If you are remote and do not have fiber connectivity or want to explore other connectivity options, you can check the following satellite operators.

Additional Connectivity options: ​

• Through additional service providers
• Datacenter providers
• National Research and Education networks (NERN)
• System integrators