Cisco Systems CL-28826-01 Understanding IPsec Technologies and Policies

24-5

User Guide for Cisco Security Manager 4.4

OL-28826-01

Chapter24 Managing Site-to-Site VPNs: The Basics

Understanding IPsec Technologies and Policies

In addition to the three main VPN topologies, other more complex topologies can be created as

combinations of these topologies. They include:

•Partial mesh—A network in which some devices are organized in a full mesh topology, and other

devices form either a hub-and-spoke or a point-to-point connection to some of the fully meshed

devices. A partial mesh does not provide the level of redundancy of a full mesh topology, but it is

less expensive to implement. Partial mesh topologies are generally used in peripheral networks that

connect to a fully meshed backbone.

•Tiered hub-and-spoke—A network of hub-and-spoke topologies in which a device can behave as a

hub in one or more topologies and a spoke in other topologies. Traffic is permitted from spoke

groups to their most immediate hub.

•Joined hub-and-spoke—A combination of two topologies (hub-and-spoke, point-to-point, or full

mesh) that connect to form a point-to-point tunnel. For example, a joined hub-and-spoke topology

could comprise two hub-and-spoke topologies, with the hubs acting as peer devices in a

point-to-point topology.