Rich,
I wasnt able to find a document that specifically discusses pinging from console but let me try and explain.
When you generate an ICMP Packet from the router for a specific destination, the ICMP Packet is sourced from the interface that has the best routing path to the destination. So, in your case when you are consoled into the router that generate an ICMP packet to the Ethernet0, since the network is directly connected, the packet is sourced from the Ethernet0 itself. And if you have an ACL denying ICMP Traffic, then you will not be able to ping.
For example:
interface GigabitEthernet0/0
ip address 10.89.245.56 255.255.255.0
ip access-group 100 in
no ip route-cache cef
duplex auto
speed auto
ntp disable
end
2821#sh deb
Generic IP:
IP packet debugging is on for access list 100
2821#sh access-lists
Extended IP access list 100
10 deny ip any any log
2821#
Debug while Pinging from Console:
2821#ping 10.89.245.56
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.89.245.56, timeout is 2 seconds:
.
*Oct 19 15:36:47.746: %SEC-6-IPACCESSLOGDP: list 100 denied icmp 10.89.245.56 ->
10.89.245.56 (0/0), 8 packets
Success rate is 0 percent (0/5)
2821#
I hope the below document answers some of your question on ICMP.
Understanding the Ping and Traceroute Commands
http://www.cisco.com/en/US/products/sw/iosswrel/ps1831/products_tech_note09186a00800a6057.shtml
Let me know if it helps.
Regards,
Arul