MSR router NAT configuration anomaly causes black hole route, direct connection to same network segment fails

Router vlanif12------------vlanif12sw

192.168.12.253-----------192.168.12.252

The router cannot be pinged by the switch and cannot learn the ARP information of the switch

Packet capture shows that the router does not send ARP requests and does not reply to ARP responses after receiving ARP requests from the switch

A black hole route for the destination address was found on the router

display  fib 192.168.12.252

FIB entry count: 1

Flag:

  U:Usable   G:Gateway   H:Host   B:Blackhole   D:Dynamic   S:Static

  R:Relay     F:FRR 

Destination/Mask   Nexthop         Flag     OutInterface/Token       Label

192.168.12.252/32  0.0.0.0         UBH      NULL0                    Null   

Other interfaces have NAT address group configurations causing black hole routes

nat address-group 1 name test

 address 192.168.12.2 192.168.12.254

interface GigabitEthernet0/0

 port link-mode route

 ip address dhcp-alloc

 tcp mss 1280

 nat outbound address-group 1

Normal after removing redundant nat configuration