Twin-region deployments utilizing Safe Digital WAN Hub with Routing-Intent with out World Attain

This text describes the perfect practices for connectivity, site visitors flows, and excessive availability of dual-region Azure VMware Resolution when utilizing Azure Safe Digital WAN with Routing Intent. You study the design particulars of utilizing Safe Digital WAN with Routing-Intent, with out World Attain. This text breaks down Digital WAN with Routing Intent topology from the angle of Azure VMware Resolution personal clouds, on-premises websites, and Azure native. The implementation and configuration of Safe Digital WAN with Routing Intent are past the scope and are not mentioned on this doc.

In areas with out World Attain assist or with a safety requirement to examine site visitors between Azure VMware Resolution and on-premises on the hub firewall, a assist ticket should be opened to allow ExpressRoute to ExpressRoute transitivity for each regional hubs. ExpressRoute to ExpressRoute transitivity is not supported by default with Digital WAN. – see Transit connectivity between ExpressRoute circuits with routing intent 

Safe Digital WAN with Routing Intent is barely supported with Digital WAN Commonplace SKU. Safe Digital WAN with Routing Intent supplies the aptitude to ship all Web site visitors and Non-public community site visitors to a safety resolution like Azure Firewall, a third-party Community Digital Equipment (NVA), or SaaS resolution. Within the situation, we have now a community topology that spans two areas. There’s one Digital WAN with two Hubs, Hub1 and Hub2. Hub1 is in Area 1, and Hub2 is in Area 2. Every Hub has its personal occasion of Azure Firewall deployed(Hub 1 Firewall, Hub 2 Firewall), basically making them every Safe Digital WAN Hubs. Having Safe Digital WAN hubs is a technical prerequisite to Routing Intent. Safe Digital WAN Hub1 and Hub2 have Routing Intent enabled.

Every area additionally has an Azure VMware Resolution Non-public Cloud and an Azure Digital Community. There’s additionally an on-premises web site connecting to each areas, which we evaluate in additional element later on this doc.

Understanding Topology Connectivity

The next sections cowl site visitors flows and connectivity for Azure VMware Resolution, on-premises, Azure Digital Networks, and the Web.

This part focuses on solely the Azure VMware Resolution personal clouds in each areas. Every Azure VMware Resolution personal cloud has an ExpressRoute connection to the hub (connections labeled as “D”).

With ExpressRoute to ExpressRoute transitivity enabled on the Safe Hub and Routing-Intent enabled, the Safe Hub sends the default RFC 1918 addresses (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) to each Azure VMware Resolution personal clouds over connection “D”. Along with the default RFC 1918 addresses, each Azure VMware Resolution personal clouds study extra particular routes from Azure Digital Networks and Networks (S2S VPN, P2S VPN, SDWAN) which can be related to each Hub 1 and Hub 2. Each Azure VMware Resolution personal clouds do not study particular routes from on-premises networks. For routing site visitors again to on-premises networks, it makes use of the default RFC 1918 addresses that it discovered through connection “D” from its native regional hub. This site visitors transits by way of the native regional Hub firewall, as proven within the diagram. The Hub firewall has the particular routes for on-premises networks and routes site visitors towards the vacation spot over connection “E”. Site visitors from each Azure VMware Resolution personal clouds, heading in the direction of Digital Networks, will transit the Hub firewall. For extra data, see the site visitors stream part.

The diagram illustrates site visitors flows from the angle of the Azure VMware Resolution Non-public Cloud Area 1 and Azure VMware Resolution Non-public Cloud Area 2.

Site visitors Stream Chart

This part focuses solely on the on-premises web site. As proven within the diagram, the on-premises web site has an ExpressRoute connection to each Hub 1 and Hub 2 (connection labeled as “E”).

With ExpressRoute to ExpressRoute transitivity enabled on each Safe Hubs and Routing-Intent enabled, every Safe Hub sends the default RFC 1918 addresses (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) to on-premises over connection “E”. Along with the default RFC 1918 addresses, on-premises learns extra particular routes from Azure Digital Networks and Department Networks (S2S VPN, P2S VPN, SDWAN) which can be related to each Hub 1 and Hub 2.

By default, on-premises doesn’t study the particular routes for each Azure VMware Resolution Non-public Clouds. As an alternative, it routes to each Azure VMware Resolution Non-public Clouds utilizing the default RFC 1918 addresses it learns over connection “E”. On-premises will study the default RFC 1918 addresses from each Hub 1 and Hub 2 through connection “E”.

To promote a extra particular route all the way down to on-premises, it must be achieved from the “Non-public Site visitors Prefixes” field inside Routing Intent. – see Configure routing intent and insurance policies by way of Digital WAN portal. You might want to add a summarized route that encompasses each your Azure VMware Resolution /22 block and your Azure VMware Resolution subnets. When you add the identical precise prefix or a extra particular prefix as a substitute of a abstract route, you introduce routing points inside the Azure setting. Subsequently, it’s necessary to do not forget that any prefixes added to the “Non-public Site visitors Prefixes” field should be summarized routes.

As illustrated within the diagram, Azure VMware Resolution Non-public Cloud 1 consists of workload subnets from 10.10.0.0/24 to 10.10.7.0/24. On Hub 1, the abstract route 10.10.0.0/21 is added to “Non-public Site visitors Prefixes” as a result of it encompasses all eight subnets. Moreover, on Hub 1, the abstract route 10.150.0.0/22 is added to “Non-public Site visitors Prefixes” to cowl the Azure VMware Resolution administration block. Abstract routes 10.10.0.0/21 and 10.150.0.0/22 are then marketed all the way down to on-premises through connection “E”, offering on-premises with a extra particular route than 10.0.0.0/8.

Azure VMware Resolution Non-public Cloud 2 consists of workload subnets from 10.20.0.0/24 to 10.20.7.0/24. On Hub 2, the abstract route 10.20.0.0/21 is added to “Non-public Site visitors Prefixes” as a result of it encompasses all eight subnets. Moreover, on Hub 2, the abstract route 10.250.0.0/22 is added to “Non-public Site visitors Prefixes.” This covers the Azure VMware Resolution administration block. Abstract routes 10.20.0.0/21 and 10.250.0.0/22 are then marketed all the way down to on-premises through connection “E.” This supplies on-premises with a extra particular route than 10.0.0.0/8.

There’s no problem in including the complete Azure VMware Resolution Administration /22 block beneath “Non-public Site visitors Prefixes” as a result of Azure VMware Resolution doesn’t promote the precise /22 block again to Azure; it all the time advertises extra particular routes.

As talked about earlier, whenever you allow ExpressRoute to ExpressRoute transitivity on the Hub, it sends the default RFC 1918 addresses (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) to your on-premises community. Subsequently, you should not promote the precise RFC 1918 prefixes (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) again to Azure. Promoting the identical precise routes creates routing issues inside Azure. As an alternative, you must promote extra particular routes again to Azure in your on-premises networks.

The diagram illustrates site visitors flows from the angle of on-premises.

Site visitors Stream Chart

This part focuses solely on connectivity from the Azure Digital Networks perspective. As depicted within the diagram, every Digital Community has a Digital Community peering on to its regional hub.

The diagram illustrates how all Azure native assets in each Digital Networks study routes beneath their “Efficient Routes”. With Routing Intent enabled, Hub 1 and Hub 2 all the time ship the default RFC 1918 addresses (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) to their peered Digital Networks. Azure native assets within the Digital Networks don’t study particular routes from outdoors their Digital Community. With Routing Intent enabled, all assets within the Digital Community presently study the default RFC 1918 tackle and use their regional hub firewall as the following hop. Azure VMware Resolution Non-public Clouds talk with one another through connection “D” to their native regional hub firewall. From there, they traverse the Digital WAN inter-hub and endure inspection on the cross-regional hub firewall. Moreover, Azure VMware Resolution personal clouds talk with on-premises through connection “D” over their native regional hub firewall. All site visitors ingressing and egressing the Digital Networks will all the time transit their regional hub firewalls. For extra data, see the site visitors stream part.

The diagram illustrates site visitors flows from the Azure Digital Networks perspective.

Site visitors Stream Chart

This part focuses solely on how web connectivity is offered for Azure native assets in Digital Networks and Azure VMware Resolution Non-public Clouds with twin area. There are a number of choices to supply web connectivity to Azure VMware Resolution. – see  Web Entry Ideas for Azure VMware Resolution 

Possibility 1: Web Service hosted in Azure
Possibility 2: VMware Resolution Managed SNAT
Possibility 3: Azure Public IPv4 tackle to NSX-T Information Heart Edge

Though you need to use all three choices with Twin Area Safe Digital WAN with Routing Intent, “Possibility 1: Web Service hosted in Azure” is the most suitable choice when utilizing Safe Digital WAN with Routing Intent and is the choice that’s used to supply web connectivity within the situation. The explanation why “Possibility 1” is taken into account the most suitable choice with Safe Digital WAN is because of its ease of safety inspection, deployment, and manageability.

As talked about earlier, whenever you allow Routing Intent on each Safe Hubs, it advertises RFC 1918 to all immediately peered Digital Networks. Nevertheless, you can even promote a default route 0.0.0.0/0 for web connectivity to downstream assets. With Routing Intent, you may select to generate a default route from each hub firewalls. This default route is marketed to its immediately peered Digital Networks and to its immediately related Azure VMware Resolution. This part is damaged into two sections, one which explains web connectivity from each regional Azure VMware Resolution perspective and one other from the Digital Networks perspective.

When Routing Intent is enabled for web site visitors, the default conduct of the Safe Digital WAN Hub is to not promote the default route throughout ExpressRoute circuits. To make sure the default route is propagated to its immediately related Azure VMware Resolution from the Azure Digital WAN, you could allow default route propagation in your Azure VMware Resolution ExpressRoute circuits – see To promote default route 0.0.0.0/0 to endpoints. As soon as adjustments are full, the default route 0.0.0.0/0 is then marketed through connection “D” from the hub. It’s necessary to notice that this setting should not be enabled for on-premises ExpressRoute circuits. As a greatest observe, it’s beneficial to implement a BGP Filter in your on-premises gear. A BGP Filter in place prevents the inadvertent studying of the default route, provides an additional layer of precaution, and ensures that on-premises web connectivity is not impacted.

Whenever you allow Routing Intent for web entry, it routinely generates a default route from each regional hubs and advertises it to their hub-peered Digital Community connections. You may discover beneath Efficient Routes for the Digital Machines’ NICs within the Digital Community that the 0.0.0.0/0 subsequent hop is the regional hub firewall. The default route is rarely marketed throughout regional hubs over the ‘inter-hub’ hyperlink. Subsequently, Digital Networks use their native regional hub for web entry and don’t have any backup web connectivity to the cross-regional hub.

For extra data, see the site visitors stream part.

The diagram illustrates site visitors flows from the Digital Networks and Azure VMware Resolution Non-public Clouds perspective.

Site visitors Stream Chart

With Azure VMware Resolution utilizing the Twin-Area with out World Attain design, you don’t have outbound web connectivity redundancy as a result of every Azure VMware Resolution personal cloud learns the default route from each its native regional hub and isn’t immediately related to its cross-regional hub. If a regional outage that impacts the native regional hub, you might have two choices with a purpose to obtain web redundancy which can be guide configurations.

Possibility 1: For Outbound Web Entry Solely
Throughout an area regional outage, for those who want outbound web entry in your Azure VMware Resolution workload, you may go for VMware Resolution Managed SNAT. It’s an easy resolution that shortly supplies the entry you want. – see Activate Managed SNAT for Azure VMware Resolution workloads 

Possibility 2: For Inbound and Outbound Web Entry
Throughout an area regional outage, for those who want each inbound and outbound web entry in your Azure VMware Resolution cloud, begin by eradicating the “D” connection in your native regional hub. Take away the Authorization Key created for the “D” connection from the Azure VMware Resolution blade within the Azure portal. Then, create a brand new connection to the cross-regional hub. For dealing with inbound site visitors, think about using Azure Entrance Door or Site visitors Supervisor to keep up regional excessive availability.

HCX Mobility Optimized Networking (MON) is an elective characteristic to allow when utilizing HCX Community Extensions (NE). Mobility Optimized Networking (MON) supplies optimum site visitors routing beneath sure situations to forestall community tromboning between the on-premises-based and cloud-based assets on prolonged networks.

Enabling Mobility Optimized Networking (MON) for a particular prolonged community and a digital machine adjustments the site visitors stream. For Mobility Optimized Networking (MON), egress site visitors from that digital machine would not trombone again to on-premises. As an alternative, it bypasses the Community Extensions (NE) IPSEC tunnel. Site visitors for that digital machine will now egress out of the Azure VMware Resolution NSX-T Tier-1 Gateway> NSX-T Tier-0 Gateway>Azure Digital WAN.

Enabling Mobility Optimized Networking (MON) for a particular prolonged community and a digital machine leads to a change. From Azure VMware Resolution NSX-T, it injects a /32 host route again to Azure Digital WAN. Azure Digital WAN advertises this /32 route again to on-premises, Digital Networks, and Department Networks (S2S VPN, P2S VPN, SDWAN). The aim of this /32 host route is to make sure that site visitors from on-premises, Digital Networks, and Department Networks (S2S VPN, P2S VPN, SDWAN) would not use the Community Extensions (NE) IPSEC tunnel when destined for the Mobility Optimized Networking (MON) enabled Digital Machine. Site visitors from supply networks is directed straight to the Mobility Optimized Networking (MON) enabled Digital Machine because of the /32 route that’s discovered.

With ExpressRoute to ExpressRoute transitivity enabled on the Safe Hub and Routing-Intent enabled, the Safe Hub sends the default RFC 1918 addresses (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) to each the on-premises and Azure VMware Resolution. Along with the default RFC 1918 addresses, each on-premises and Azure VMware Resolution study extra particular routes from Azure Digital Networks and Department Networks (S2S VPN, P2S VPN, SDWAN) which can be related to the hub. Nevertheless, on-premises networks do not study any particular routes from the Azure VMware Resolution, nor does the reverse happen. As an alternative, each environments depend on the default RFC 1918 addresses to facilitate routing again to 1 one other through their native regional Hub firewall. Which means that extra particular routes, akin to HCX Mobility Optimized Networking (MON) Host Routes, aren’t marketed from the Azure VMware Resolution ExpressRoute to the on-premises-based ExpressRoute circuit and vice-versa. The lack to study particular routes introduces uneven site visitors flows. Site visitors egresses Azure VMware Resolution through the NSX-T Tier-0 gateway, however returning site visitors from on-premises returns over the Community Extensions (NE) IPSEC tunnel.

To appropriate any site visitors asymmetry, you’ll want to regulate the HCX Mobility Optimized Networking (MON) Coverage Routes. Mobility Optimized Networking (MON) coverage routes decide which site visitors goes again to the on-premises Gateway through an L2 extension. Additionally they resolve which site visitors is routed by way of the Azure VMware Resolution NSX Tier-0 Gateway.

If a vacation spot IP matches and is ready to “enable” within the Mobility Optimized Networking (MON) coverage configuration, then two actions happen. First, the packet is recognized. Second, its despatched to the on-premises gateway by way of the HCX Community Extension equipment.

If a vacation spot IP would not match or is ready to “deny” within the Mobility Optimized Networking (MON) coverage, the system sends the packet to the Azure VMware Resolution Tier-0 for routing.

HCX Coverage Routes