NAT traversal encapsulates ESP-protected traffic in UDP 4500 so a translating intermediate router can handle the session; that addresses IPsec connectivity across translating perimeter devices, rather than functional MTU negotiation through IPsec overhead.

AWS sends IKE negotiation to the configured customer endpoint, so an unreachable or incorrect outside address prevents establishment; this belongs to accurate public termination identity for a hybrid VPN, while the problem is functional MTU negotiation through IPsec overhead.

In the compatible IKE negotiation parameters workflow, phase-one negotiation requires both peers to agree on IKE and cryptographic parameters before protected traffic can traverse the tunnel; the current case needs functional MTU negotiation through IPsec overhead.

Independent tunnel peerings expose route availability to BGP so routing can respond when one encrypted path fails; that addresses dual-tunnel BGP monitoring and failover, rather than compatible IKE negotiation parameters.

VPN resilience depends on reachability of both independently addressed AWS tunnel endpoints, not merely having two configured AWS tunnels; this belongs to perimeter firewall support for both VPN tunnels, while the problem is compatible IKE negotiation parameters.

In the accurate public termination identity for a hybrid VPN workflow, AWS sends IKE negotiation to the configured customer endpoint, so an unreachable or incorrect outside address prevents establishment; the current case needs compatible IKE negotiation parameters.

This produces device-diverse hybrid IPsec termination: A customer gateway identifies each peer router or endpoint; separate connections prevent all tunnels from depending on a single customer device; the stem instead tests compatible IKE negotiation parameters.

VPN resilience depends on reachability of both independently addressed AWS tunnel endpoints, not merely having two configured AWS tunnels; that addresses perimeter firewall support for both VPN tunnels, rather than configured prefixes for a statically routed VPN.

An established IPsec security association does not by itself exchange dynamic networks; BGP must originate acceptable prefixes across the tunnel; this changes propagation of corporate networks using VPN BGP, not the necessary configured prefixes for a statically routed VPN.

In the attachment-specific route propagation to spoke forwarding tables workflow, without VPN route propagation or equivalent static routes, spoke traffic has no transit next hop toward dynamically learned branch prefixes; the current case needs configured prefixes for a statically routed VPN.

When BGP receives eligible paths, route preference determines whether one tunnel is primary; two tunnels alone do not imply standby selection; this belongs to deliberate active-passive VPN path selection, while the problem is dual-tunnel BGP monitoring and failover.

An established IPsec security association does not by itself exchange dynamic networks; BGP must originate acceptable prefixes across the tunnel; this changes propagation of corporate networks using VPN BGP, not the necessary dual-tunnel BGP monitoring and failover.

In the consistent BGP authentication on the circuit workflow, BGP session authentication rejects segments that fail the shared-key validation even when the VLAN and IP interfaces are correct; the current case needs dual-tunnel BGP monitoring and failover.

BGP opening messages verify peer ASN expectations; a mismatch prevents a stable routing adjacency despite physical reachability; that addresses BGP neighbor ASN agreement, rather than point-to-point address alignment for BGP peering.

Connect peers use defined transport endpoints and BGP inside addressing; arbitrary overlapping interface addresses cannot establish the intended GRE peer; this belongs to valid endpoint addressing for TGW Connect GRE peers, while the problem is point-to-point address alignment for BGP peering.

In the correct VLAN tagging for a Direct Connect virtual interface workflow, direct Connect VIFs identify their layer-two sessions by VLAN tag; untagged frames do not enter the expected BGP peer context; the current case needs point-to-point address alignment for BGP peering.

A LAG aggregates compatible physical links within one facility; geographically separate circuits require independent connections or LAGs; this belongs to supported physical membership of a DX link aggregation group, while the problem is consistent BGP authentication on the circuit.

BGP reachability depends on using the allocated peer addresses on the correct VLAN, not arbitrary addresses from a workload subnet; this changes point-to-point address alignment for BGP peering, not the necessary consistent BGP authentication on the circuit.

In the distinction between circuit health and routing session health workflow, layer-one connection state does not guarantee a valid VLAN or BGP session; VIF-level configuration determines routing adjacency; the current case needs consistent BGP authentication on the circuit.

The subnet's effective route table must contain a destination route toward the VGW for return traffic, independent of tunnel negotiation; that addresses VPC-side routing for corporate destination prefixes, rather than attachment-specific route propagation to spoke forwarding tables.

TGW prefixes on the hybrid side do not automatically populate VPC subnet route tables; the instance-side forwarding path must also exist; this belongs to VPC forwarding toward known corporate networks, while the problem is attachment-specific route propagation to spoke forwarding tables.

In the configured prefixes for a statically routed VPN workflow, static VPN routing requires configured destination prefixes; no BGP advertisements populate the list automatically; the current case needs attachment-specific route propagation to spoke forwarding tables.

Transit Gateway associations originate explicitly allowed prefixes toward Direct Connect BGP peers; missing allowed prefixes can leave no AWS route advertisements; that addresses controlled BGP advertisement via DX gateway allowed prefixes, rather than ownership-aware DX gateway association approval.

A hosted connection must be accepted by its recipient before that account can configure and use its virtual interface; this belongs to account acceptance of a provider-provisioned hosted circuit, while the problem is ownership-aware DX gateway association approval.

The private VPN tunnel rides the private Direct Connect connectivity toward the transit gateway rather than attaching directly to a public VIF; this changes underlying private transport for encrypted TGW connectivity, not the necessary ownership-aware DX gateway association approval.

This produces correct gateway attachment for transit virtual interfaces: The transit VIF architecture reaches transit gateways through a Direct Connect gateway; VGW connectivity uses a private VIF pattern; the stem instead tests ownership-aware DX gateway association approval.

When BGP receives eligible paths, route preference determines whether one tunnel is primary; two tunnels alone do not imply standby selection; this belongs to deliberate active-passive VPN path selection, while the problem is customer-side outbound route selection between hybrid links.

The private VPN tunnel rides the private Direct Connect connectivity toward the transit gateway rather than attaching directly to a public VIF; this changes underlying private transport for encrypted TGW connectivity, not the necessary customer-side outbound route selection between hybrid links.

In the propagation of corporate networks using VPN BGP workflow, an established IPsec security association does not by itself exchange dynamic networks; BGP must originate acceptable prefixes across the tunnel; the current case needs customer-side outbound route selection between hybrid links.

VPN resilience depends on reachability of both independently addressed AWS tunnel endpoints, not merely having two configured AWS tunnels; this belongs to perimeter firewall support for both VPN tunnels, while the problem is valid endpoint addressing for TGW Connect GRE peers.

The private VPN tunnel rides the private Direct Connect connectivity toward the transit gateway rather than attaching directly to a public VIF; this changes underlying private transport for encrypted TGW connectivity, not the necessary valid endpoint addressing for TGW Connect GRE peers.

In the point-to-point address alignment for BGP peering workflow, BGP reachability depends on using the allocated peer addresses on the correct VLAN, not arbitrary addresses from a workload subnet; the current case needs valid endpoint addressing for TGW Connect GRE peers.

NAT traversal encapsulates ESP-protected traffic in UDP 4500 so a translating intermediate router can handle the session; that addresses IPsec connectivity across translating perimeter devices, rather than stable VPN encapsulation across NAT devices.

AWS sends IKE negotiation to the configured customer endpoint, so an unreachable or incorrect outside address prevents establishment; this belongs to accurate public termination identity for a hybrid VPN, while the problem is stable VPN encapsulation across NAT devices.

In the perimeter firewall support for both VPN tunnels workflow, VPN resilience depends on reachability of both independently addressed AWS tunnel endpoints, not merely having two configured AWS tunnels; the current case needs stable VPN encapsulation across NAT devices.