graph TD
    A[On-Prem Router] -->|BGP/Private Peering| B[ER Circuit (Standard)]
    B --> C[ER Gateway (Hub VNet)]
    C --> D1[Spoke VNet 1]
    C --> D2[Spoke VNet 2]
    C --> D3[Spoke VNet 3]

graph TD
    A1[On-Prem DC - South Central] -->|BGP| B1[ER Circuit - South Central (Premium)]
    A2[On-Prem DC - East] -->|BGP| B2[ER Circuit - East (Premium)]

    B1 --> C1[ER GW - Hub South Central US]
    B2 --> C2[ER GW - Hub East US]

    C1 --> D1[Spoke VNet 1 - South Central]
    C1 --> D2[Spoke VNet 2 - South Central]
    C2 --> E1[Spoke VNet 1 - East]
    C2 --> E2[Spoke VNet 2 - East]

    B1 <--> B2[Global Reach]

Change ID: CHG-AZR-ER-2025-07
Date: 2025-07-15
Summary: ER Circuit upgrade + Hub redesign for segmentation and HA
Action:
- Upgraded ER circuit to Premium
- Deployed new ER GW in Central US
- Connected 3 spoke VNets using regional hub
- Enabled Global Reach with East US circuit
Impact: Improved BCDR and removed prefix limit error observed during routing updates

# Get ExpressRoute Circuit Details
$circuit = Get-AzExpressRouteCircuit -ResourceGroupName "rg-network" -Name "er-circuit-premium"
$circuit | Format-List Name,ServiceProviderProperties,BandwidthInMbps,PeeringLocation,Sku

# List all Peerings
Get-AzExpressRouteCircuitPeering -ExpressRouteCircuit $circuit

# Validate Peering Connection Status
$circuit.Peerings | ForEach-Object {
    Write-Host "Peering: $($_.PeeringType) | State: $($_.State) | AzureASN: $($_.AzureASN)"
}

# Get associated VNet Gateway and Connections
$vng = Get-AzVirtualNetworkGateway -ResourceGroupName "rg-network" -Name "er-gw-central"
Get-AzVirtualNetworkGatewayConnection -VirtualNetworkGateway1 $vng | Format-Table Name,ConnectionType,ConnectionStatus

data "azurerm_express_route_circuit" "er_circuit" {
  name                = "er-circuit-premium"
  resource_group_name = "rg-network"
}

output "er_circuit_details" {
  value = {
    service_provider_name = data.azurerm_express_route_circuit.er_circuit.service_provider_name
    peering_location      = data.azurerm_express_route_circuit.er_circuit.peering_location
    bandwidth             = data.azurerm_express_route_circuit.er_circuit.bandwidth_in_mbps
    sku                   = data.azurerm_express_route_circuit.er_circuit.sku[0].name
  }
}

data "azurerm_virtual_network_gateway" "er_gateway" {
  name                = "er-gw-central"
  resource_group_name = "rg-network"
}

output "gateway_bgp_settings" {
  value = data.azurerm_virtual_network_gateway.er_gateway.bgp_settings
}