Cannot ping external address without source address

[Adam_S]

Hi all,

Need some help. I have a cisco 3845 connected to a 3750 switch. I am unable to ping external addresses directly from either the 3750 switch or 3845 router without a source address. 

Amel-router#ping 8.8.8.8
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 8.8.8.8, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
Amel-router#ping 8.8.8.8 source 10.12.0.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 8.8.8.8, timeout is 2 seconds:
Packet sent with a source address of 10.12.0.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms

I can tested by sourcing the ping from all available interfaces, works fine and pings from the connected devices work fine too.

[MHM Cisco World]

OK then how interface use for Overload it subnet use in ACL of NAT ??

ip nat inside source list NAT-ACL interface Vlan80 overload
!
Extended IP access list NAT-ACL
40 permit ip 192.168.80.0 0.0.0.255 any (25 matches) <<<<--- that WRONG friend 

[Adam_S]

Interesting. I never realised that before.

[Adam_S]

Thanks to all that assisted. Suddely issue is resolved it is now pinging correctly from the router with need to specifiy source address (issue still remains on switch).

[MHM Cisco World]

Do you remove the ACL Line from NAT-ACL ?

[Wizard4777]

so what was the solution? i am experiencing the exact same issue

[Georg Pauwen]

Hello,

by default, the outgoing interface is the source of the ping. What does your configuration look like, what are you pinging ?

[Wizard4777]

Ping to 8.8.8.8.8

[Richard Burts]

It is not clear in the original discussion what was done that resolved the issue. And we do not have enough information about your situation to have much idea about what would resolve your issue. If ping to 8.8.8.8 is not successful my first guess would be possible problems with network address translation. Would you post the config so that we can see how NAT is set up?
It might also be helpful if you would post the output of these commands:

show ip interface brief

show ip route

show ip nat translations

[Wizard4777]

NAT is fine. Issue is ping to 8.8.8.8.8 with source from inside receives a
reply. There is no reply if ping or trace without source

[Adam_S]

This was a long time back. I think i updated the IOS.

[Wizard4777]

Acknowledged