Refer to the Exhibit.
Given the existing operational network shown in the exhibit, you now want to add a remote site for
Customer B to the PE3 router. This change should not have an effect on the existing BGP
sessions between the PE routers. Which Layer 3 VPN scaling mechanism allows PE3 to begin
receiving Customer B routes?
A.
route origin
B.
route refresh
C.
route reflection
D.
route target filtering
Explanation:
http://www.juniper.net/documentation/en_US/junos12.3/topics/concept/vpn-routing-tables-vpn-forwarding-tables.html
VPN route processing differs from normal BGP route processing in one way. In BGP, routes are accepted if they are not explicitly rejected by import policy. However, because many more VPN routes are expected, the Junos OS does not accept (and hence store) VPN routes unless the route matches at least one VRF import policy. If no VRF import policy explicitly accepts the route, it is discarded and not even stored in the bgp.l3vpn.0 table. As a result, if a VPN change occurs on a PE router—such as adding a new VRF table or changing a VRF import policy—the PE router sends a BGP route refresh message to the other PE routers (or to the route reflector if this is part of the VPN topology) to retrieve all VPN routes so they can be reevaluated to determine whether they should be kept or discarded.
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I’m thinking B as I don’t find any “refresh” feature
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it is default enabled..
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A soft reset allows the application of a new or changed policy without clearing an active BGP session. The route-refresh feature allows a soft reset to occur on a per-neighbor basis and does not require preconfiguration or extra memory.
A dynamic inbound soft reset generates inbound updates from a neighbor. An outbound soft reset sends a new set of updates to a neighbor. Outbound resets do not require preconfiguration or routing table update storage.
The route-refresh feature requires that both BGP peers advertise route-refresh feature support in the OPEN message. If the route-refresh method is successfully negotiated, either BGP peer can use the route-refresh feature to request full routing information from the other end.
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