Comprehensive and Detailed In-Depth Explanation:
1. Understanding Route Targets (RT) and Route Distribution in MPLS VPN
* MPLS Layer 3 VPNs (L3VPNs) use BGP to distribute VPN routes across multiple Provider Edge (PE) routers.
* Each VPN instance (VRF) is configured with Route Targets (RTs) to control which VPN routes are imported/exported.
* Route Distinguishers (RDs) are unique per VRF but do not affect route selection.
2. Analyzing VPN1 Configuration
* VPN1 is exporting routes with the following Route Targets (vpn-target values):
* 100:1
* 200:1
* 300:1
* Remote VPNs will import these routes only if their import RT list matches one of the exported RTs.
3. Matching Exported RTs with Import RTs in Remote VPNs
Remote VPN
Import RTs
Matches VPN1 Exported RTs (100:1, 200:1, 300:1)?
Accepts the Route?
VPN1
100:1
# Matches 100:1
# Yes
VPN2
200:1, 400:1
# Matches 200:1
# Yes
VPN3
100:1, 300:1
# Matches 100:1, 300:1
# Yes
VPN4
500:1
# No match
# No
# VPN1, VPN2, and VPN3 accept the route.# VPN4 does not accept the route because 500:1 is not in the export list of VPN1.
Final Conclusion:
# Correct answer: VPN1, VPN2, and VPN3 will accept the route.# VPN4 does not accept the route because there is no matching RT.
Thus, the correct answer is:# A. VPN1: Import RT=100:1# B. VPN2: Import RT=200:1, 400:1# C. VPN3:
Import RT=100:1, 300:1# D. VPN4: Import RT=500:1 (No match, does not accept the route).