ping router's ip Destination host unreahable in the same subnet

[Taylor Xu]

PC and router are on the same subnet，pc1 ping the router returns  Destination host unreachable。change the mac address of pc，ping was ok。

all switch has no acl、802.1x and port security；

the router has no acl configuration。

The cisco 24s is Core Switch, vlan 10 interface ip is 192.168.16.250.   ping 192.168.16.250 was ok.  ping the router's ip was failed.

Can somebody help me？ 

[ammahend]

do you see arp table populated correctly with changed MAC in PC and router ?

vlan 10 allowed on trunk ?

[Taylor Xu]

IP/MAC was correct in router's arp table.

vlan 10 allowed on trunk ,because some other PCs  were normally.

[Taylor Xu]

When you ping the router on the PC, the router will update its own arp table. In the arp table of the router, you can see the IP and MAC of the PC, but the PC does not receive any reply, and the arp table of the PC is not updated.

[MHM Cisco World]

If this is lab, then save config shut no shut and check again. 

Some time the emulated software have bug make somo node have same mac.

[Taylor Xu]

it's not a lab,it's a production env.

[MHM Cisco World]

Ping broadcast of subnet see if other pc and router reply to this ping 

If you receive same then check OS firewall of PC it can drop the ping reply.

[Taylor Xu]

yes,some other diffrent pcs replied this ping.

[MHM Cisco World]

In SW1 and SW2 check 

Vlan -mac in show mac address table'

Are the pc and router mac is add to correct vlan in  both SW?

[Taylor Xu]

PC's mac was added to both SW.  But router's mac was added to the access SW, Cant find the router's mac in CoreSW（Cisco24S）. Why?

[MHM Cisco World]

I Have suspect of secondary IP you add' remove secondary IP of router and check mac appear or not.

[Taylor Xu]

i've removed the secondary ip,but router's mac still not appear in CoreSW.

DC-Core-Cisco-3850-1#show mac address-table int gigabitEthernet 1/0/1
Mac Address Table
-------------------------------------------

Vlan Mac Address Type Ports
---- ----------- -------- -----
DC-Core-Cisco-3850-1#

[MHM Cisco World]

Try from router ping broadcast of subnet and check mac.

[Taylor Xu]

Router：Internet 172.24.16.169 0 a08c.fdcb.928b ARPA GigabitEthernet0/1

             Internet 172.24.16.254 - 00f2.8b31.6a01 ARPA GigabitEthernet0/1

CoreSwitch：DC-Core-Cisco-3850-1#show mac address-table | include 00f2
                     DC-Core-Cisco-3850-1#show mac address-table | include 928b
                          10 a08c.fdcb.928b DYNAMIC Po11
                     DC-Core-Cisco-3850-1#

                   DC-Core-Cisco-3850-1#show arp | include 16.254
                    Internet 172.24.16.254 0 00f2.8b31.6a01 ARPA Vlan10
                    DC-Core-Cisco-3850-1#show arp | include 16.169
                    Internet 172.24.16.169 0 a08c.fdcb.928b ARPA Vlan10
                   DC-Core-Cisco-3850-1#

Same result  ：(

[Taylor Xu]

Not all PCs are like this(ping Gateway failed) in vlan 10, only a few PCs(mac address) have such a fault.