ExpressRoute connectivity partners to campus network?

Question

Hi All,

I recently went through a discussion about connectivity to the cloud from the campus network which left me thinking how you could connect big campus network with high bandwidth requirements towards the Azure without any DC? My first choice was VPN, the thing is VPNs are limited in terms of the throughput, so I was wondering how else you could delivery connectivity from the big office network to the azure? After some research I think using ExpressRoute with connectivity partners could be an option so you ask ISP like British Telecom to provide you with ExpressRoute from your office location to the azure, the thing is I don't even know if that's a valid solution? Are there even companies that facilitate solutions like this? Or I misunderstand entire concept of ExpressRoute with connectivity partners? Can someone shed some light on this?

Answer 1

Hello @David Jones ,

Welcome to Microsoft Q&A Platform. Thank you for reaching out & hope you are doing well.

I understand that you would like to know how ExpressRoute works with connectivity partners.

As explained in the below document, you can choose from the 3 service provider offerings depending upon your own infrastructure.

https://learn.microsoft.com/en-us/azure/expressroute/expressroute-connectivity-models

• Colocation is the practice of renting space for your servers and other computing hardware at a third-party provider’s data center facility. If you are co-located at an Ethernet/Cloud exchange provider facility, then you can opt for this offering. They provide both layer 2 and layer 3 connections.
• Point-to-point Ethernet connections are opted when you are not co-located with a cloud exchange and need to extend your network directly to Microsoft cloud through the Ethernet links. Even Point-to-point Ethernet providers can offer Layer 2 connections, or managed Layer 3 connections.
• Any-to-any (IPVPN) network connections are opted when you have an existing WAN connecting your main office and other branch offices. In this case, Microsoft cloud can be interconnected to your WAN to make it appear like any other branch office. WAN providers typically offer managed Layer 3 connectivity.

You can find the list of connectivity providers by location in the below document:

https://learn.microsoft.com/en-us/azure/expressroute/expressroute-locations-providers#partners

To setup Azure ExpressRoute, please go through the below docs:

• Prerequisites: https://learn.microsoft.com/en-us/azure/expressroute/expressroute-prerequisites
• Workflows: https://learn.microsoft.com/en-us/azure/expressroute/expressroute-workflows
• Routing requirements: https://learn.microsoft.com/en-us/azure/expressroute/expressroute-routing
• FAQs: https://learn.microsoft.com/en-us/azure/expressroute/expressroute-faqs

Now, coming to the difference between layer 2 and layer 3 connections.

Azure ExpressRoute provides layer 3 connectivity between your on-premises network and the Microsoft Cloud through a connectivity provider and uses BGP routing protocol to exchange routes between your on-premises network, your instances in Azure, and Microsoft public addresses.

Azure ExpressRoute works on layer 3 and the only difference in the service provider connectivity is if they manage the routing or not.

If your service provider offers layer 2 connectivity services, then you will need to create and manage the routing configuration for your ExpressRoute circuit.

• Pro: You have full access to change the routing configuration at any time you want.
• Con: You need to manage and check any BGP issues that may arise.

If you're using a service provider that offers managed layer 3 services (typically an IPVPN, like MPLS), your connectivity provider configures and manages the routing for you.

• Pro: Your service provider creates and manages the routing for you.
• Con: You will not have direct access to the routing configuration and will need to check with your service provider in case of any issues/changes.

Refer: https://learn.microsoft.com/en-us/azure/expressroute/expressroute-howto-routing-portal-resource-manager

To summarize:

• In layer 2 connection, the service provider will only take care of the physical connectivity and will not handle routing for you.
• In layer 3 connection, the service provider will take care of both physical connectivity and routing.

You can go through the below articles which provides architectural best practices and uses for Azure ExpressRoute.

Refer: https://learn.microsoft.com/en-us/azure/well-architected/service-guides/azure-expressroute

https://learn.microsoft.com/en-us/azure/architecture/reference-architectures/hybrid-networking/expressroute

Kindly let us know if the above helps or you need further assistance on this issue.

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Answer 2

Hi David, Welcome to MS Q&A

ExpressRoute allows customers to create private connections between Microsoft datacenters and their on-premises infrastructure or colocation facilities. Here’s how it works and how connectivity partners can facilitate this solution:

How ExpressRoute Works

1. Private Connections: ExpressRoute provides private connectivity to Azure services, bypassing the public internet, which can result in more reliable and faster connections.
2. Connectivity Partners: Customers can use connectivity partners (such as ISPs) to establish these private connections. These partners provide the physical connection from your location to the Azure datacenters.
3. Peering Locations: Customers can select a regional carrier and land Ethernet connections to one of the supported exchange provider locations and then peer with Microsoft at the provider location.

Steps to Set Up ExpressRoute

1. Select a Connectivity Partner: Choose a connectivity partner from the list of ExpressRoute partners. For example, British Telecom (BT) is one such partner.
2. Establish Connection: Work with the connectivity partner to establish a connection from your office location to the Azure datacenter.
3. Create ExpressRoute Circuit: Follow the steps in the Create an ExpressRoute circuit guide to set up the connectivity.

Companies Facilitating ExpressRoute

There are several system integrators and connectivity partners listed on the ExpressRoute connectivity partners and peering locations page that can assist with onboarding to ExpressRoute. If your connectivity provider isn't listed, you can still create a connection by extending your network to the peering location of choice and ordering an ExpressRoute circuit with the exchange as your connectivity provider.

References

• ExpressRoute FAQ
• ExpressRoute connectivity partners and peering locations
• Create an ExpressRoute circuit

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Please let us know if any further questions

Thanks
Deepanshu