Route Reflector Support in Contrail Control Node
Contrail Networking supports Route Reflector (RR) functionality in the Control node for Internal Border Gateway Protocol (iBGP) peers. Route reflection is a BGP feature that enables BGP routers to acquire route information from one iBGP router and reflect or advertise the information to other iBGP peers in the same autonomous system (AS).
In a large scale AS, deploying BGP routers peering with the Control Node in a full-mesh topology affects scalability and leads to maintenance and configurational issues. The issues are caused while exchanging large volumes of routing information and maintaining connectivity among a large number of devices in the AS. A Route Reflector provides a scalable alternative to full-mesh internal BGP peering. See Figure 1.
You can create any number of RRs in the network. Each RR must have a unique cluster ID to prevent looping among the RRs.
Contrail nodes support Edge Reflection Multicasting Virtual Private Networking (ERMVPN) of the BGP Address Family. As non-Contrail nodes do not support ERMVPN, RR is configured separately for Contrail nodes, and external BGP speakers. If a single RR is deployed between Contrail nodes and non-Contrail nodes, the RR cannot advertise ERMVPN routes to the Contrail nodes. Contrail deploys a separate RR peering session among Contrail nodes that supports ERMVPN and helps in propagating routes among all Contrail nodes.
Benefits of RRs in Contrail
RRs can be deployed at multiple locations in the network, which helps to scale the BGP network at lower cost.
The RR feature conserves data center rack space by replacing physical route reflectors.