OpenStack ASR1000 plugin: Overview
L3 functionality in OpenStack has some limitations. One limitation is the inability to easily leverage hardware based routing technologies which provide scale, throughput, and in some cases functionality that is lacking from the existing software based solutions. Another limitation is the lack of high availability models which are prevalent in most datacenter environments, especially for a services as important as the gateway forwarding function. (Note: This is (partially) addressed with DVR, but some issues remain) Via the standard OpenStack Neutron plugin architecture, the OpenStack ASR1000 plugin addresses these shortfalls.
To provide a fully functional L3 service, the plugin supports these features:
1) Support for static L3 forwarding between associated tenant L2 networks (and their associated L3 subnets)
2) Support for overlapping IP address ranges between different tenants (so each tenant could use the same RFC-1918 IPv4 address space)
3) Support for NAT Overload (or PAT) for connections originating behind the tenant router and targeting a device on (or through) an “external” network.
4) Support for NAT for connections originating from (or through) an “external” network targeting a specific tenant network attached device (VM).
In addition, in order to support data center resiliency models, a high availability feature is also provided to support the above features. For L3 forwarding, this is multiple router redundancy with a L3 redundancy protocol; namely HSRP.
The OpenStack ASR1000 Plugin was first supported in the Liberty release. There are versions which support Mitaka and Newton, and Ocata support is planned
The OpenStack ASR1000 Plugin is open source software associated with OpenStack. As such it is available in the Cisco Systems openStack repository @ ....