4 The environment

The environment/topology that this guide centres on

A high-level view of what this guide helps you build:

The green cloud = the Azure backbone network with the perimeter of the cloud representing the connection point of an Azure NIC into a Subnet within a VNet.

Each green line denotes a connection from a 'Gigabit' interface or a Loopback interface on each CSR 1000v:

1. Gigabit1 = 'Management' (not shown - same path as 'Outside')
2. Gigabit2 = 'Outside'
3. Gigabit3 = 'DMZ'
4. Gigabit4 = 'Inside'

All thick blue lines represent logical 'overlay' networks that are formed over the green 'underlay' paths.

• The lines leaving each router and meeting inside the cloud represent mGRE tunnel interfaces that dynamic tunnels are built over. 2 colours = 2 separate topologies for 'Dev and QA' and 'Prod'.
• The lines between pairs of routers represent VXLAN GPE tunnels.

A view of a single stage's resources in a single site from an Azure perspective:

Each of the subnets has a User Defined Route (UDR) table attached. Here are the routes that will be added:

Attached Subnet	Routes
Management
	none
Outside
	DMZ prefix via CSR 1000v Outside (Gig2) interface IP address
	Inside prefix via CSR 1000v Outside (Gig2) interface IP address
DMZ
	0.0.0.0/0 via CSR 1000v DMZ (Gig3) interface IP address
	Outside prefix via CSR 1000v DMZ (Gig3) interface IP address
	Inside prefix via CSR 1000v DMZ (Gig3) interface IP address
Inside
	0.0.0.0/0 via CSR 1000v DMZ (Gig4) interface IP address
	Outside prefix via CSR 1000v DMZ (Gig4) interface IP address
	DMZ prefix via CSR 1000v DMZ (Gig4) interface IP address