Added spec file for bgpaas-route-origin Spec file contains all inform…

…ation related to bgpaas-route-origin

Partial-Bug: #1657132

Raising this review on behalf of Aamir Raza
Reviewed by: Nischal, Rahul, Raja S and Paul Carver
Approved by: Ashish

Change-Id: I7e52b7a11aa957e1da3aae1b5fd9be9ed79db70c

specs/bgpaas_route_origin.md

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+#1. Introduction
+Contrail BGP route exchange carries Route Origin attribute, which is also used
+as a tie breaker while choosing a prefered route path. However in certain cases
+Administrator/user may not want Route Origin to contribute to route selection.
+
+#2. Problem statement
+While learning routes from BGP Peer Contrail can receive routes with different
+Route Origin attributes for same route prefix, which may be expected to form
+ECMP, however because of different values of Route Origin it ends up choosing
+one path over other.
+
+####Use case
+In particular this requirement is in context of supporting a virtual Load
+Balancer VNF. Where Route Origin should be normalised for routes received from
+VNF, to avoid its contribution to route selection
+
+#3. Proposed solution
+As PNF routers already allow overriding Route Origin attribute, same can be
+extended to contrail BGP implementation as well to normalize Route Origin
+attribute for received BGP routes.
+Similar to PNF routers, contrail BGP should be able to override Route Origin
+attribute while importing a route from a BGP peer
+
+##3.1 Alternatives considered
+NA
+
+##3.2 API schema changes
+Route Origin override will be added as an element under BgpSessionAttributes
+
+##3.3 User workflow impact
+User can use VNC APIs to configure override Route Origin as part of BGP session
+attributes while creating or updating bgp-router object
+Alternatively contrail UI can be used to configure override, while currently
+as per use case this will be added only to BGPaas wizard
+Where it will allow choice between predefined values of IGP, EGP or INCOMPLETE
+
+##3.4 UI changes
+In BGPaas wizard following changes are required
+* Under Advanced Options, add a new drop down for **BGP Origin**
+* The BGP Origin field has 3 values **IGP**, **EGP** and **INCOMPLETE**
+* The origin-override field in bgpaas-session-attributes property should be set to false by default.
+* Under Advanced Options, add a new checkbox for **Enable Origin Override**. This should cause 
+  origin-override field in bgpaas-session-attributes property to be set to True.
+* To override BGP Origin, select a value from **BGP Origin** drop down field and check the **Origin 
+  override** checkbox
+
+
+##3.5 Notification impact
+There were no changes made in logs, UVEs or alarms.
+
+
+#4. Implementation
+##4.1 Work items
+####Config Schema
+As per section 3.2
+
+####Control-node
+Control node will read this Route Origin override information associated with a
+BGP Peer and apply override to routes received from peer
+
+####Contrail-UI
+As per section 3.4
+
+#5. Performance and scaling impact
+##5.1 API and control plane
+No impact
+
+##5.2 Forwarding performance
+No impact
+
+#6. Upgrade
+No impact
+
+#7. Deprecations
+There are no deprecations when this change is made.
+
+#8. Dependencies
+There are no dependencies for this feature.
+
+#9. Testing
+##9.1 Unit tests
+Unit Test Cases will be added to validate added code
+
+##9.2 Dev tests
+Validate Route Origin override for the routes imported from BGP peer and BGPaas
+
+##9.3 System tests
+Validate the solution function against the Virtual Load Balancer VNF use case
+
+#10. Documentation Impact
+The details of Route Origin Override have to be added in the user documentation.
+
+#11. References
+[bgp_design](http://juniper.github.io/contrail-vnc/bgp_design.html)
+
+[adding-bgp-knob-to-opencontrail](http://www.opencontrail.org/adding-bgp-knob-to-opencontrail/)
+
+[contrail-controller (source-code)](https://github.com/Juniper/contrail-controller/tree/master/src/vnsw/agent)