Exam 3V0-25.25 Topic 2 Question 31 Discussion

Explanation:
* Active-Standby Tier-0 Gateway
* Active-Standby Tier-1 Gateway
In aVMware Cloud Foundation (VCF)multi-site or multi-instance architecture, established viaNSX Federation, secure connectivity between sites is often achieved throughIPSec VPN. IPSec VPN is considered a stateful service within the NSX networking stack.
Stateful services-which also include NAT and Load Balancing-require a centralized point of processing to maintain the security association (SA) and session state tables. In the NSX gateway architecture, this necessitates the presence of aService Router (SR)component. For stateful consistency and to avoid session disruption that would occur if asymmetric traffic were processed by different nodes, these gateways must operate in anActive-Standbyhigh-availability mode.
According to the "NSX-T Data Center VPN Configuration Guide," IPSec VPN services can be deployed on either the provider tier (Tier-0 Gateway) or the tenant tier (Tier-1 Gateway). When configured on a Tier-0 gateway, the VPN typically provides broad connectivity between the physical infrastructure of two sites.
When configured on a Tier-1 gateway, it often provides targeted connectivity for a specific project or department's workload segments.
Configurations involvingActive-Activegateways (whether Tier-0 or Tier-1) do not support the native NSX IPSec VPN service because the ECMP (Equal Cost Multi-Pathing) nature of Active-Active mode could lead to packets belonging to the same VPN tunnel being processed by different Edge nodes, which cannot share the real-time encryption state. Therefore, for an administrator to successfully implement a cross-location VPN in a VCF Fleet, they must ensure the target gateway-be it Tier-0 or Tier-1-is deployed inActive-Standby mode.