Which of the following is true regarding RTC? (Select the best answer.)

Last Updated on August 7, 2021 by Admin 3

Which of the following is true regarding RTC? (Select the best answer.)

  • RTC sends only the prefixes that the PE router wants.
  • RTC finds route inconsistencies.
  • RTC synchronizes peers without a hard reset.
  • RTC works with only VPNv4.
  • RTC makes the ABR an RR and sets the next hop to self.
Explanation:
Route Target Constraint (RTC) sends only the prefixes that the Provider Edge (PE) router wants. In a normal Multiprotocol Label Switching (MPLS) virtual private network (VPN), the route reflector (RR) sends all of its VPN version 4 (VPNv4) and VPNv6 prefixes to the PE router. The PE router then drops the prefixes for which it does not have a matching VPN routing and forwarding (VRF). RTC allows a PE router to send its route target (RT) membership data to the RR within an address family named rtfilter. The RR then uses rtfilter to determine which prefixes to send to the PE. In order for RTC to work, both the RR and the PE need to support RTC.
RTC does not find route inconsistencies, nor does it synchronize peers without a hard reset. This functionality is provided by Border Gateway Protocol (BGP) Enhanced Route Refresh.
BG Enhanced Route Refresh is enabled by default. If two BGP peers support EnhancedRoute Refresh, each peer will send a RouteRefresh StartofRIB (SOR) message and a RouteRefresh EndofRIB (EOR) message before and after an AdjRIBOut message, respectively. After a peer receives an EOR message, or after the EOR timer expires, the peer will check to see whether it has any routes that were not readvertised. If any stale routes remain, they are deleted and the route inconsistency is logged.
RTC does not make the area border router (ABR) an RR, nor does it set the next hop to self. This behavior is exhibited by Unified MPLS. Unified MPLS increases scalability for an MPLS network by extending the label switched path (LSP) from end to end, not by redistributing interior gateway protocols (IGPs) into one another, but by distributing some of the IGP prefixes into BGP. BGP then distributes those prefixes throughout the network.

0 0 votes
Article Rating
Subscribe
Notify of
guest
0 Comments
Inline Feedbacks
View all comments