Layer 3 Vpn Design - Avaya 8800 Planning And Engineering

MPLS IP VPN and IP VPN Lite

Layer 3 VPN design

The Layer 3 VPNs are implemented using Avaya IP VPN Lite.
To provide address space for the IPinIP encapsulation, each Avaya Ethernet Routing Switch
8800/8600 is also configured with a second CLIP network address (the Service IP) which is
created using a 24-bit mask rather than a host 32-bit mask.
Layer 3 VPNs are then configured by first creating a VRF instance at all the sites where the
VPN must terminate. As shown in the following figure, IP VLANs local to each site can then
be assigned to the relevant VRF, thus ensuring IP routing connectivity between VLANs
assigned only to the same VRF instance, but no IP routing towards other IP VLANs assigned to
other VRF instances. Each VRF then has IP VPN functionality enabled which allows it to belong
to one or more Layer 3 VPNs. This configuration is done by assigning an appropriate Route
Distinguisher (RD) and import and export Route Targets (RT) to the VRF IP VPN configuration.
The end result being that BGP automatically installs remote IP routes from remote VRFs
belonging to the same VPN into the local VRF and vice versa. Furthermore each Layer 3 VPN
can be created as any-any, hub-spoke or multihub-spoke by simple manipulation of the import
and export RTs as per the RFC 4364 framework.
Figure 108: Example of two separate Layer 3 VPNs
232 Planning and Engineering — Network Design November 2010