When the base router has one or more RTC peers (BGP peers with which the RT Constraint capability has been successfully negotiated), one RTC route is created for each RT extended community imported into a locally-configured L2 VPN or L3 VPN service. These imported route targets are configured in the following contexts:
config>service>vprn
config>service>vprn>mvpn
By default, these RTC routes are automatically advertised to all RTC peers, without the need for an export policy to explicitly ‟accept” them. Each RTC route has a prefix, a prefix length and path attributes. The prefix value is the concatenation of the origin AS (a 4-byte value representing the 2- or 4-octet AS of the originating router, as configured using the config>router>autonomous-system command) and 0 or 16-64 bits of a route target extended community encoded in one of the following formats: 2-octet AS specific extended community, IPv4 address specific extended community, or 4-octet AS specific extended community.
A router may be configured to send the default RTC route to any RTC peer. This is done using the new default-route-target group/neighbor CLI command. The default RTC route is a special type of RTC route that has zero prefix length. Sending the default RTC route to a peer conveys a request to receive all VPN routes (regardless of route target extended community) from that peer. The default RTC route is typically advertised by a route reflector to its clients. The advertisement of the default RTC route to a peer does not suppress other more specific RTC routes from being sent to that peer.