300-510 · Question #196
Refer to the exhibit. A network engineer is investigating a report of packet drops in an application running on a server connected to PE2. The engineer determined that: - The OSPF adjacency in area 0
The correct answer is C. RR1(config)# router bgp 100. The scenario describes an asymmetric traffic problem: PE1-to-PE2 works (meaning PE1 has a BGP route to PE2's prefix), but PE2-to-PE1 is dropping packets (meaning PE2 lacks a valid BGP route back to PE1's prefix). In a route reflector topology, route reflectors learn routes from c
Question
Refer to the exhibit. A network engineer is investigating a report of packet drops in an application running on a server connected to PE2. The engineer determined that:
- The OSPF adjacency in area 0 is up, and it is learning the loopback
addresses of all routers in area 0.
- Traffic from users connected to PE1 to the application is also
passing normally.
- Packets from PE2 back to PE1 are being dropped.
Which action resolves the issue?
Exhibit
Options
- ARR2(config)# router bgp 100
- BRR1(config)# router bgp 100
- CRR1(config)# router bgp 100
- DRR2(config)# router bgp 100
How the community answered
(46 responses)- A20% (9)
- B4% (2)
- C65% (30)
- D11% (5)
Explanation
The scenario describes an asymmetric traffic problem: PE1-to-PE2 works (meaning PE1 has a BGP route to PE2's prefix), but PE2-to-PE1 is dropping packets (meaning PE2 lacks a valid BGP route back to PE1's prefix). In a route reflector topology, route reflectors learn routes from clients and reflect them to other clients. If RR1 is not properly configured as a route reflector or is not reflecting PE1's prefixes to PE2, PE2 will not have a BGP route toward PE1 and will drop return traffic. The fix (Answer C, applied on RR1) involves adding the appropriate BGP route-reflector client configuration so RR1 reflects PE1's routes to PE2. Since the OSPF underlay is confirmed working and PE1→PE2 traffic flows normally, the problem is isolated to the BGP control plane on the return path, specifically a missing or misconfigured route-reflector client relationship on RR1 for PE2.
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