I feel like it is time for another update on VMware Cloud Director (VCD) capabilities regarding establishing L2 VPN between on-prem location and Org VDC. The previous blog posts were written in 2015 and 2018 and do not reflect changes related to usage of NSX-T as the underlying cloud network platform.
The primary use case for L2 VPN to the cloud is migration of workloads to the cloud when the L2 VPN tunnel is temporarily established until migration of all VMs on single network is done. The secondary use case is Disaster Recovery but I feel that running L2 VPN permanently is not the right approach.
But that is not the topic of today’s post. VCD does support setting up L2 VPN on tenant’s Org VDC Gateway (Tier-1 GW) from version 10.2 however still it is hidden, API-only feature (the GUI is finally coming soon … in VCD 10.3.1). The actual set up is not trivial as the underlying NSX-T technology requires first IPSec VPN tunnel to be established to secure the L2 VPN client to server communication. VMware Cloud Director Availability (VCDA) version 4.2 is an addon disaster recovery and migration solution for tenant workloads on top of VCD and it simplifies the set up of both the server (cloud) and client (on-prem) L2 VPN endpoints from its own UI. To reiterate, VCDA is not needed to set up L2 VPN, but it makes it much easier.
The screenshot above shows the VCDA UI plugin embeded in the VCD portal. You can see three L2 VPN session has been created on VDC Gateway GW1 (NSX-T Tier-1 backed) in ACME-PAYG Org VDC. Each session uses different L2 PVN client endpoint type.
The on-prem client can be existing NSX-T tier-0 or tier-1 GW, NSX-T autonomous edge or standalone Edge client. And each requires different type of configuration, so let me discuss each separately.
NSX-T Tier-0 or Tier-1 Gateway
This is mostly suitable for tenants who are running existing NSX-T environment on-prem. They will need to set up both IPSec and L2VPN tunnels directly in NSX-T Manager and is the most complicated process of the three options. On either Tier-0 or Tier-1 GW they will first need to set up IPSec VPN and L2 VPN client services, then the L2VPN session must be created with local and remote endpoint IPs and Peer Code that must be retrieved before via VCD API (it is not available in VCDA UI, but will be available in VCD UI in 10.3.1 or newer). The peer code contains all necessary configuration for the parent IPSec session in Base64 encoding.
Standalone Edge Client
This option leverages the very light (150 MB) OVA appliance that can be downloaded from NSX-T download website and actually works both with NSX-V and NSX-T L2 VPN server endpoints. It does not require any NSX installation. It provides no UI and its configuration must be done at the time of deployment via OVF parameters. Again the peer code must be provided.
This is the prefered option for non-NSX environments. Autonomous edge is a regular NSX-T edge node that is deployed from OVA, but is not connected to NSX-T Manager. During the OVA deployment Is Autonomous Edge checkbox must be checked. It provides its own UI and much better performance and configurability. Additionally the client tunnel configuration can be done via the VCDA on-premises appliance UI. You just need to deploy the autonomous edge appliance and VCDA will discover it and let you manage it from then via its UI.
This option requires no need to retrieve the Peer Code as the VCDA plugin will retrieve all necessary information from the cloud site.
The previous VMware Cloud Director 10.2 release brought many new networking features, the current one 10.3 continuous in the same fashion. Let me give you a brief run down.
The UI has been enhanced to surface formerly API only features such as the ability to configure dual stack IPv4/IPv6 networks:
or configure DHCP in gateway or network mode:
The service provider can now assign/change primary IP address of Org VDC Edge Gateway in the UI:
It is also possible to configure (extend) an external network port group backing without using API.
New NSX-T Backed Provider VDC Features
As NSX-T backed PVDCs now support both Tier-0/VRF and port group backing for external networks, to avoid confusion the Tier-0/VRF GWs were separated into its own tab.
The port group backed external networks can be either traditional VDS port groups, or NSX-T segments. The latter option gives the ability to use NSX-T distributed firewall on such external network (provider managed directly in NSX-T).
Distributed Firewall now supports dynamic groups that can be defined utilizing VM Tag or VM name.
vApps support routed vApp networks including DHCP service on vApp isolated networks. This is achieved by deploying standalone Tier-1 GWs that are connected to Org VDC networks via service interface. The Org VDC network must be overlay backed (not VLAN). vApp fencing is still not supported as NSX-T does not provide this functionality.
A few additional small enhancements ranging from support for Guest VLAN tagging, reflexive NAT to DHCP pool management.
Provider VDC with no NSX
The creation of Provider VDC does not require network pool specification anymore. Such PVDC will thus not provide any NSX-V or T features (routing, DHCP, firewalling, load balancing). The Org VDC network can than be backed by VLAN network pool or use VDS backed imported direct networks.
NSX-V vs NSX-T Feature Parity
Let me conclude with traditional NSX-V / NSX-T VCD feature comparison chart (new updates highlighted in green).
The tool’s main purpose is to automate migration of VMware Cloud Director Organization Virtual Data Centers that are NSX-V backed to a NSX-T backed Provider Virtual Data Center. The original article describes how exactly it is accomplished and what is the impact of migrated workloads from the networking and compute perspective.
The migration tool is continually developed and additional features are added to either enhance its usability (improved roll back, simplified L2 bridging setup) or to support more use cases based on new features in VMware Cloud Director (VCD). And then there is a new assessment mode! Let me go into more details.
Directly Connected Networks
The VCD release 10.2.2 added support to use in NSX-T backed Org VDCs directly connected Organization VDC networks. Such networks are not connected to a VDC Gateway and instead are just connected directly to a port group backed external network. The typical usage is for service networks, backup networks or colocation/MPLS networks where routing via the VDC Gateway is not desired.
The migration tool now supports migration of these networks. Let me describe how it is done.
The VCD external network in NSX-V backed PVDC is port group backed. It can be backed by one or more port groups that are typically manually created VLAN port groups in vCenter Server or they can also be VXLAN backed (system admin would create NSX-V logical switch directly in NSX-V and then use its DVS port groups for the external network). The system administrator then can create in the Org VDC a directly connected network that is connected to this external network. It inherits its parent’s IPAM (subnet, IP pools) and when tenant connects a VM to it it is just wired to the backing port group.
The migration tool first detects if the migrated Org VDC direct network is connected to an external network that is also used by other VDCs and based on that behaves differently.
Colocation / MPLS use case
If the external network is not used by any other Org VDC and the backing port group(s) is VLAN type (if more port groups are used they must have the same VLAN), then it will create in NSX-T logical segment in VLAN transport zone (specified in the YAML input spec) and import it to the target Org VDC as imported network. The reason why direct connection to external network is not used is to limit the external network sprawl as the import network feature perfectly matches the original use case intent. After the migration the source external network is not removed automatically and the system administrator should clean them up including the vCenter backing port groups at their convenience.
Note that no bridging is performed between the source and target network as it is expected the VLAN is trunked across source and target environments.
The diagram below shows the source Org VDC on the left and the target one on the right.
Service Network Use Case
If the external network is used by other Org VDCs, the import VLAN segment method cannot be used as each imported Org VDC network must be backed by its own logical segment and has its own IPAM (subnet, pool). In this case the tool will just create directly connected Org VDC network in the target VDC connected to the same external network as the source. This requires that the external network is scoped to the target PVDC – if the target PVDC is using different virtual switch you will need first to create regular VLAN backed port group there and then add it to the external network (API only currently). Also only VLAN backed port group can be used as no bridging is performed for such networks.
The other big feature is the assessment mode. The main driver for this feature is to enable service providers to see how much ready their environment is for the NSX-V to T migration and how much redisign will be needed. The assessment can be triggered against VCD 10.0, 10.1 or 10.2 environments and only requires VCD API access (the environment does not yet need to be prepared for NSX-T).
The tool will during the assessment check all or specified subset of NSX-V backed Org VDCs and assess every feature used there that impacts its migration viability. Then it will provide detailed and summarized report where you can see what ratio of the environment *could* be migrated (once upgraded to the latest VCD 10.2.2). This is provided in Org VDC, VM and used RAM units.
The picture below shows example of the summary report:
Note that if there is one vApp in a particular Org VDC that cannot be migrated, the whole Org VDC is counted as not possible to migrate (in all metrics VM and RAM). Some features are categorized as blocking – they are simple not supported by either NSX-T backed Org VDC or the migration tool (yet), but some issues can be mitigated/fixed (see the remediation recommendations in the user guide).
As mentioned the migration tool is continuosly developed and improved. Together with the next VMware Cloud Director version we can expect additional coverage of currently unsupported features. Especially the shared network support is high on the radar.
This is going to be a bit longer than usual and more of a summary / design option type blog post where I want to discuss provider networking in VMware Cloud Director (VCD). By provider networking I mean the part that must be set up by the service provider and that is then consumed by tenants through their Org VDC networking and Org VDC Edge Gateways.
With the introduction of NSX-T we also need to dive into the differences between NSX-V and NSX-T integration in VCD.
Note: The article is applicable to VMware Cloud Director 10.2 release. Each VCD release is adding new network related functionality.
Provider Virtual Datacenters
Provider Virtual Datacenter (PVDC) is the main object that provides compute, networking and storage resources for tenant Organization Virtual Datacenters (Org VDCs). When a PVDC is created it is backed by vSphere clusters that should be prepared for NSX-V or NSX-T. Also during the PVDC creation the service provider must select which Network Pool is going to be used – VXLAN backed (NSX-V) or Geneve backed (NSX-T). PVDC thus can be backed by either NSX-V or NSX-T, not both at the same time or none at all and the backing cannot be changed after the fact.
Speaking of Network Pools – they are used to create on-demand routed/isolated networks by tenants. The Network Pools are independent from PVDCs, can be shared across multiple PVDCs (of the same backing type). There is an option to automatically create VXLAN network pool with PVDC creation but I would recommend against using that as you lose the ability to manage the transport zone backing the pool on your own. VLAN backed network pool can still be created but can be used only in PVDC backed by NSX-V (same for very legacy port group backed network pool now available only via API). Individual Org VDCs can (optionally) override the Network Pool assigned of its parent PVDC.
Deploying virtual machines without the ability to connect to them via network is not that usefull. External networks are VCD objects that allow the Org VDC Edge Gateways connect to and thus reach the outside world – internet, dedicated direct connections or provider’s service area. External network have associated one or more subnets and IP pools that VCD manages and uses them to allocate external IP addresses to connected Org VDC Edge Gateways.
There is a major difference how external networks are created for NSX-V backed PVDCs and for NSX-T ones.
Port Group Backed External Network
As the name suggest these networks are backed by an existing vCenter port group (or multiple port groups) that must be created upfront and is usually backed by VLAN (but could be a VXLAN port group as well). These external networks are (currently) supported only in NSX-V backed PVDCs. Org VDC Edge Gateway connected to this network is represented by NSX-V Edge Service Gateway (ESG) with uplink in this port group. The uplinks have assigned IP address(es) of the allocated external IPs.
Directly connected Org VDC network connected to the external network can also be created (only by the provider) and VMs connected to such network have uplink in the port group.
Tier-0 Router Backed External Network
These networks are backed by an existing NSX-T Tier-0 Gateway or Tier-0 VRF (note that if you import to VCD Tier-0 VRF you can no longer import its parent Tier-0 and vice versa). The Tier-0/VRF must be created upfront by the provider with correct uplinks and routing configuration.
Only Org VDC Edge Gateways from NSX-T backed PVDC can be connected to such external network and they are going to be backed by a Tier-1 Gateway. The Tier-1 – Tier-0/VRF transit network is autoplumbed by NSX-T using 100.64.0.0/16 subnet. The allocated external network IPs are not explicitly assigned to any Tier-1 interface. Instead when a service (NAT, VPN, Load Balancer) on the Org VDC Edge Gateway starts using assigned external address, it will be advertised by the Tier-1 GW to the linked Tier-0 GW.
There are two main design options for the Tier-0/VRF.
The recommended option is to configure BGP on the Tier-0/VRF uplinks with upstream physical routers. The uplinks are just redundant point-to-point transits. IPs assigned from any external network subnet will be automatically advertised (when used) via BGP upstream. When provider runs out of public IPs you just assign additional subnet. This makes this design very flexible, scalable and relatively simple.
An alternative is to use design that is similar to the NSX-V port group approach, where Tier-0 uplinks are directly connected to the external subnet port group. This can be useful when transitioning from NSX-V to T where there is a need to retain routability between NSX-V ESGs and NSX-T Tier-1 GWs on the same external network.
The picure below shows that the Tier-0/VRF has uplinks directly connected to the external network and a static route towards the internet. The Tier-0 will proxy ARP requests for external IPs that are allocated and used by connected Tier-1 GWs.
The disadvantage of this option is that you waste public IP addresses for T0 uplink and router interfaces for each subnet you assign.
Note: Proxy ARP is supported only if the Tier-0/VRF is in Active/Standby mode.
Tenant Dedicated External Network
If the tenant requires direct link via MPLS or a similar technology this is accomplished by creating tenant dedicated external network. With NSX-V backed Org VDC this is represented by a dedicated VLAN backed port group, with NSX-T backed Org VDC it would be a dedicated Tier-0/VRF. Both will provide connectivity to the MPLS router. With NSX-V the ESG would run BGP, with NSX-T the BGP would have to be configured on the Tier-0. In VCD the NSX-T backed Org VDC Gateway can be explicitly enabled in the dedicated mode which gives the tenant (and also the provider) the ability to configure Tier-0 BGP.
There are seprate rights for BGP neighbor configuration and route advertisement so the provider can keep BGP neighbor configuration as provider managed setting.
Note that you can connect only one Org VDC Edge GW in the explicit dedicated mode. In case the tenant requires more Org VDC Edge GWs connected to the same (dedicated) Tier-0/VRF the provider will not enable the dedicated mode and instead will manage BGP directly in NSX-T (as a managed service).
Often used use case is when the provider directly connects Org VDC network to such dedicated external network without using Org VDC Edge GW. This is however currently not possible to do in NSX-T backed PVDC. There instead, you will have to import Org VDC network backed by NSX-T logical segment (overlay or VLAN).
Internet with MPLS
The last case I want to describe is when the tenant wants to access both Internet and MPLS via the same Org VDC Edge GW. In NSX-V backed Org VDC this is accomplished by attaching internet and dedicated external network portgroups to the ESG uplinks and leveraging static or dynamic routing there. In an NSX-T backed Org VDC the provider will have to provision Tier-0/VRF that has transit uplink both to MPLS and Internet. External (Internet) subnet will be assigned to this Tier-0/VRF with small IP Pool for IP allocation that should not clash with any other IP Pools.
If the tenant will have route advertisement right assigned then route filter should be set on the Tier-0/VRF uplinks to allow only the correct prefixes to be advertised towards the Internet or MPLS. The route filters can be done either in NSX-T direclty or in VCD (if the Tier-0 is explicitly dedicated).
The diagram below shows example of an Org VDC that has two Org VDC Edge GWs each having access to Internet and MPLS. Org VDC GW 1 is using static route to MPLS VPN B and also has MPLS transit network accessible as imported Org VDC network, while Org VDC GW 2 is using BGP to MPLS VPN A. Connectivity to the internet is provided by another layer of NSX-T Tier-0 GW which allows usage of overlay segmens as VRF uplinks and does not waste physical VLANs.
One comment on usage of NAT in such design. Usually the tenant wants to source NAT only towards the Internet but not to the MPLS. In NSX-V backed Org VDC Edge GW this is easily set on per uplink interface basis. However, that option is not possible on Tier-1 backed Org VDC Edge GW as it has only one transit towards Tier-0/VRF. Instead NO SNAT rule with destination must be used in conjunction with SNAT rule.
When NSX-T 3.1 was released a few days ago, the feature that I was most looking for was the ability to share Geneve overlay transport VLAN between ESXi transport nodes and Edge transport nodes.
Before NSX-T 3.1 in a collapsed design where Edge transport nodes were running on ESXi transport nodes (in other words NSX-T Edge VMs were deployed to NSX-T prepared ESXi cluster) you could not share the same transport (TEP) VLAN unless you would dedicate separate physical uplinks for Edge traffic and ESXi underlay host traffic. The reason is that the Geneve encapsulation/decapsulation was happening only on the physical uplink in/egress and that point would be skipped for intra-host datapath between the Edge and host TEP VMkernel port.
This was quite annoying because the two transport VLANs need to route between each other at full jumbo MTU>1600 frame size. So in lab scenarios you had to have additional router taking care of that. And I have seen multiple time issues due to misconfigured router MTU size.
After upgrading my lab to NSX-T 3.1 I was eager to test it.
Here are the steps I used to migrate to single transport VLAN:
The collapsed Edge Nodes will need to use trunk uplinks created as NSX-T logical segment. My Edge Nodes used regular VDS port group so I renamed the old ones in vCenter and created new trunks in NSX-T Manager.
(Optional) Create new TEP IP Address Pool for the Edges. You can obviously use the ESXi host IP Pool as now they will share the same subnet, or you can use static IP addressing. I opted for new IP Address Pool with the same subnet as my ESXi host TEP IP Address Pool but a different range so I can easily distinguish host and edge TEP IPs.
Create new Edge Uplink Profile VLAN to match the ESXi transport VLAN.
Now for each Edge node repeat this process: edit the node in the Edge Transport Node Overview tab, change its Uplink Profile, IP Pool and uplinks to the created ones in steps #1, #2 and #3. Refresh and observe the Tunnel health.
Clean up now unused Uplink Profile, IP Pool and VDS uplinks.
Deprovision now unused Edge Transport VLAN from physical switches and from the physical router interface.
During the migration I saw one or two pings to drop but that was it. If you see tunnel issues try to put the edge node briefly into NSX Maintenance Mode.