VPP three-layer network interconnection configuration

as follows L3XC Plug in function test topology ：

 |--------------|           |--------------|          |--------------|
 |              |           |              |          |              |
 |     PC1      |-----------|     VPP      |----------|     PC2      |
 |              |           |              |          |              |
 |--------------|           |--------------|          |--------------|
    11.1.2.2              11.1.1.1      12.1.1.1         12.1.1.100
                          TG3/0/0       TG3/0/1 

VPP edition

vpp# show version
vpp v21.10.1-release built by root on 4f6ead0c141f at 2021-11-17T14:25:30

Set up VPP Address of the interface ：

vpp# set interface state TenGigabitEthernet3/0/0 up
vpp# set interface state TenGigabitEthernet3/0/1 up
vpp# 
vpp# set interface ip address TenGigabitEthernet3/0/0 11.1.1.1/16
vpp# set interface ip address TenGigabitEthernet3/0/1 12.1.1.1/16

Set up l3xc, from TG3/0/0 The traffic coming in , Forwarding to TG3/0/1 Gateway address of the interface 12.1.1.100; conversely , from TG3/0/1 Incoming traffic is forwarded to TG3/0/0 Gateway address of the interface 11.1.2.2. as follows ：

vpp# l3xc add ip4 TenGigabitEthernet3/0/0 via 12.1.1.100 TenGigabitEthernet3/0/1
vpp#
vpp# l3xc add ip4 TenGigabitEthernet3/0/1 via 11.1.2.2 TenGigabitEthernet3/0/0

Show l3xc Configuration information ：

vpp# show l3xc
l3xc:[0]: TenGigabitEthernet3/0/0
    path-list:[222] locks:1 flags:shared,no-uRPF, uPRF-list:103 len:1 itfs:[2, ]
      path:[226] pl-index:222 ip4 weight=1 pref=0 attached-nexthop:  oper-flags:resolved,
        12.1.1.100 TenGigabitEthernet3/0/1
      [@0]: ipv4 via 12.1.1.100 TenGigabitEthernet3/0/1: mtu:9000 next:4 flags:[] 6891d06265230060e07a6c790800

  [@1]: dpo-load-balance: [proto:ip4 index:219 buckets:1 uRPF:-1 to:[0:0]]
      [0] [@5]: ipv4 via 12.1.1.100 TenGigabitEthernet3/0/1: mtu:9000 next:4 flags:[] 6891d06265230060e07a6c790800
l3xc:[1]: TenGigabitEthernet3/0/1
    path-list:[223] locks:1 flags:shared,no-uRPF, uRPF-list: None
      path:[227] pl-index:223 ip4 weight=1 pref=0 attached-nexthop:  oper-flags:resolved,
        11.1.2.2 TenGigabitEthernet3/0/0
      [@0]: ipv4 via 11.1.2.2 TenGigabitEthernet3/0/0: mtu:9000 next:3 flags:[] 6891d06265220060e07a6c780800

  [@1]: dpo-load-balance: [proto:ip4 index:220 buckets:1 uRPF:-1 to:[0:0]]
      [0] [@5]: ipv4 via 11.1.2.2 TenGigabitEthernet3/0/0: mtu:9000 next:3 flags:[] 6891d06265220060e07a6c780800

PC1 And PC2 The flow between them can be connected .