H31-161 Question #174: Real Exam Question with Answer & Explanation

Refer to the exhibit. As shown in the figure, CE 1 and CE 3 belong to VPN-A, and CE 2 and CE 4 belong to VPN-B. VPN-target of VPN-A is 111:1, and that of VPN-B is 222:2.Users on different VPNs are not allowed to access each other. Configuration principles are as follows: 1. On the backbone network, if a PE is connected to a CE, VPN instances need to be configured on the PE, and an interface on the PE for connecting to the CE must be bound to a VPN instance. After binding an interface to a VPN instance, you must configure the IP address of the interface.Between PEs, IS-IS is configured for PE interworking, MPLS basic capabilities and MPLS LDP are configured for MPLS LSP establishment, and MP-IBGP is configured for VPN route exchange. LDP is short for Label Distribution Protocol, and IBGP is short for Interior Border Gateway Protocol. 2. A CE exchanges VPN routes with a PE over External Border Gateway Protocol (EBGP). Which of the following configurations of PE 1 is incorrect? (A) (1) Configure Interior Gateway Protocol (IGP) on the IS-IS+MPLS backbone network to achieve the interworking between PEs and P routers. # Configure PE 1 as follows: [PE 1] isis 100 [PE 1-isis-100] is-level level-2 [PE 1-isis-100] network-entity 10.1234.1234.1234.00 [PE 1] interface loopback1 [PE 1-LoopBack1] ip address 1.1.1.9 32 [PE 1-LoopBack1] isis enable [PE 1-LoopBack1] quit [PE 1] interface pos3/0/0 [PE 1-Pos3/0/0] ip address 172.1.1.1 24 [PE 1-Pos3/0/0] isis enable [PE 1-Pos3/0/0] quit (2) Configure MPLS basic capabilities and MPLS LDP for setting up LDP LSPs on the IS- IS+MPLS backbone network. # Configure PE 1 as follows: [PE 1] mpls lsr-id 1.1.1.9 [PE 1] mpls [PE 1-mpls] lsp-trigger all [PE 1-mpls] quit [PE 1] mpls ldp [PE 1-mpls-ldp] quit [PE 1] interface pos 3/0/0 [PE 1-Pos3/0/0] mpls [PE 1-Pos3/0/0] mpls ldp [PE 1-Pos3/0/0] quit (3) Configure VPN instances on a PE for connecting CEs to the PE. # Configure PE 1 as follows: [PE 1] ip vpn-instance vpna [PE 1-vpn-instance-vpna] route-distinguisher 100:1 [PE 1-vpn-instance-vpna] vpn-target 111:1 both [PE 1-vpn-instance-vpna] quit [PE 1] ip vpn-instance vpnb [PE 1-vpn-instance-vpnb] route-distinguisher 100:2 [PE 1-vpn-instance-vpnb] vpn-target 222:2 both [PE 1-vpn-instance-vpnb] quit [PE 1] interface gigabitethernet 1/0/0 [PE 1-GigabitEthernet1/0/0] ip binding vpn-instance vpna [PE 1-GigabitEthernet1/0/0] ip address 10.1.1.2 24 [PE 1-GigabitEthernet1/0/0] quit [PE 1] interface gigabitethernet 2/0/0 [PE 1-GigabitEthernet2/0/0] ip binding vpn-instance vpnb [PE 1-GigabitEthernet2/0/0] ip address 10.2.1.2 24 [PE 1-GigabitEthernet2/0/0] quit (4) Set up an EBGP peer relationship between a PE and a CE and import VPN routes. # Configure PE 1 as follows: [PE 1] bgp 100 [PE 1-bgp] ipv4-family vpn-instance vpna [PE 1-bgp-vpna] peer 10.1.1.1 as-number 65410 [PE 1-bgp-vpna] import-route direct [PE 1-bgp-vpna] quit [PE 1-bgp] ipv4-family vpn-instance vpnb [PE 1-bgp-vpnb] peer 10.2.1.1 as-number 65420 [PE 1-bgp-vpnb] import-route direct [PE 1-bgp-vpnb] quit (5) Set up an MP-IBGP peer relationship between PEs. # Configure PE 1 as follows: [PE 1] bgp 100 [PE 1-bgp] peer 3.3.3.9 as-number 100 [PE 1-bgp] peer 3.3.3.9 connect-interface loopback 1 [PE 1-bgp] ipv4-family vpnv4 [PE 1-bgp-af-vpnv4] peer 3.3.3.9 enable [PE 1-bgp-af-vpnv4] quit