rajeevsrikant
Expert
Expert

VMware on AWS - L2 Extension

Hi

i have the below query regarding VMware on AWS.

VMC support L2 extension, which means I can extend my on premise network to AWS

Question:1

Were will be the default gateway for a network when I extend using L2 ? Will it be in on prem or will it be in both

If it is on prem then different vlan communication has to go through my on prem DC

If the DG is both on prem & in AWS, does it mean it uses some thing like Universal logical switch , Universal distributed router functionality using Anycast?

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12 Replies
T180985
Expert
Expert

The default gateway will be the T1 (DLR) Router which is distributed across hosts, theyre not appliances like with NSX-V, The T1 router handles east west traffic

Please mark helpful or correct if my answer resolved your issue. How to post effectively on VMTN https://communities.vmware.com/people/daphnissov/blog/2018/12/05/how-to-ask-for-help-on-tech-forums
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rajeevsrikant
Expert
Expert

Thanks.

So you mean for a network say Network A, for on prem VMs the D.G will be on prem GW & for VMs in VMware SDDC in AWS it will be T1 (DLR) Router

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rajeevsrikant
Expert
Expert

if you have any documentation with respect to this please share it.

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T180985
Expert
Expert

Well as the T1 router is distributed across hosts, the DG for a given subnet technically resides on all hosts...

East-West Routing

NSX-T: Routing where you need it (multi-hypervisor & multi-cloud)

Please mark helpful or correct if my answer resolved your issue. How to post effectively on VMTN https://communities.vmware.com/people/daphnissov/blog/2018/12/05/how-to-ask-for-help-on-tech-forums
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rajeevsrikant
Expert
Expert

is this also applicable to VMware on AWS

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T180985
Expert
Expert

Yes, Its applicable to VMC on AWS. They have to be created via the VMC Cloud console though, not via your on prem vcenter

Please mark helpful or correct if my answer resolved your issue. How to post effectively on VMTN https://communities.vmware.com/people/daphnissov/blog/2018/12/05/how-to-ask-for-help-on-tech-forums
nightrider7731
Contributor
Contributor

Gateway (SVI) remains on-prem.  Intra-vlan communication within an SDDC stays within the SDDC.  Communication to other vlans within the same SDDC must go back on-prem to the gateway unless proximity routing (PR) is enabled.  PR is enable first on the vlan, then on VMs.  VMs with PR enabled can talk across VLANS within the SDDC without return to the on-prem gateway.

rajeevsrikant
Expert
Expert

Thanks. Few clarifications.

Based on your explanation with PR, the D.G will be available in both on Prem & SDDC

For ex VLAN 10 : 10.10.10.0/24 & VLAN 20 : 20.20.20.0/24

The above VLAN is available in On Prem. With network extension using HCX the same network will also be available in SDDC (VMC)

The DG for both VLAN 10(10.10.10.1) & 20(20.20.20.1) will be available both on prem & on SDDC

With SDDC Communication:

VMS in VLAN 10 & VMs in VLAN 20 (within SDDC) can communicate with each other using the DG available in SDDC.

This communication will not cross   the SDDC

Communication between SDDC & On Prem

VMS in VLAN 10 (On Prem- on prem DG ) & VLAN 20 (SDDC- SDDC DG) has to go through the L2 extension

Let me know if my understanding is right

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mdinisoae
Enthusiast
Enthusiast

If you make reference to the "Extending Networks with VMware HCX" here is the right documentation: Extending Networks with VMware HCX

Walkthrough link: HCX Network Extension and Traffic Flow | VMware Cloud on AWS | VMware

If you make reference to L2 VPN with SDDC,  here is the right documentation: Configure a Layer 2 VPN and Extended Network Segment

Walkthrough link: Setting up L2 VPN in NSX-T | VMware Cloud on AWS | VMware

MDINISOAE Please mark "Helpful" or "Correct Answer" if my answer satisfies your query.
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rajeevsrikant
Expert
Expert

Thanks.

I gone through the link. It looks L2 VPN & HCX looks the same in both scenario we are extending the networks

is my understanding right

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mdinisoae
Enthusiast
Enthusiast

Both option are providing the same functionalities: extending an OnPrem subnet to VMC on AWS (Layer 2 VPN).

In addition to the L2 VPN (HCX network extension) HCX is providing more functions:

- HCX IX: allows you to use Migration (Live vMotion, Cold vMotion and Bulk Migration) and HCX DRaaS based on Replication Protocol ()

Here is an video from an old HCX version, but the principle is the same for the new HCX with Service Mesh topology.

VMware Cloud Office Hours - Hybrid Cloud eXtension - YouTube

MDINISOAE Please mark "Helpful" or "Correct Answer" if my answer satisfies your query.
ebernard
Enthusiast
Enthusiast

Rajeev,

Even if both are doing L2 Extension, it's slightly different:

- L2 extension is the way to go, if you just need to get workloads on both side (on premises and cloud) to communicate or eventually doing a VM per VM migration. But you really need to plan this interconnection for workload communication at an app level within same subnet.

- HCX Network extension: HCX main purpose is to migrate with many options (cold migration, hot migration, change VM options like thin/thick disk, VM tools version, virtual hardware...) with the ability to stretch a DVS to the Cloud. So, you have the ability to migrate VMs and keeping same IP, same subnet and eventually unstretch this network once your entire subnet has been migrated if needed to avoid the tromboning effect (default gateway stays at source side).

I hope these explanation helps you to understand the difference between the two. You have to know that both of these are included in VMware Cloud on AWS at no additional costs: virtual appliance are provided within the interface.

Cheers

Emmanuel

Emmanuel BERNARD
Lead Solution Engineer | VMware Cloud | EMEA

Please mark "Helpful" or "Correct Answer" if applies. Appreciate it.
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