Avaya 8800 Planning And Engineering, Network Design page 112

Layer 3 network design
Figure 38: Inter-VRF forwarding based on external firewall
Although customer data separation into Layer 3 virtual routing domains is usually a requirement,
sometimes customers must access a common network infrastructure. For example, they want to
access the Internet, data storage, VoIP-PSTN, or call signaling services. To interconnect VRF
instances, you can use an external firewall that supports virtualization, or use inter-VRF forwarding
for specific services. Using the interVRF solution, routing policies and static routes can be used to
inject IP subnets from one VRF instance to another, and filters can be used to restrict access to
certain protocols.
The following figure shows inter-VRF forwarding. In this solution, routing policies can be used to
leak IP subnets from one VRF to another. Filters can be used to restrict access to certain protocols.
This enables hub-and-spoke network designs for, for example, VoIP gateways.
Figure 39: Inter VRF communication, internal inter-VRF forwarding
June 2016 Planning and Engineering — Network Design
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